HP TM 11-6625-2779-14-P User Manual

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TECHNICAL MANUAL

OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, AND

GENERAL SUPPORT MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS)

FOR

METER, AUDIO LEVEL TA-885/U

(HEWLETT-PACKARD MODEL 3555B)

(NSN 6625-00-255-1083)

TM 11-6625-2779-14&P

HEADQUARTERS, DEPARTMENT OF THE ARMY

11 MARCH 1980

TM 11-6625-2779-14&P

This manual contains copyrighted material reproduced by permission of Hewlett-Packard Company. All rights are reserved.

TECHNICAL MANUAL HEADQUARTERS

DEPARTMENT OF THE ARMY.

No. 11-6625-2779-14&P WASHINGTON, DC, 11 March 1980

OPERATOR'S, ORGANIZATIONAL, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS AND

SPECIAL TOOLS LISTS) FOR

METER, AUDIO LEVEL TA-885/U

(HEWLETT-PACKARD MODEL 3555B)

(NSN 6625-00-255-1083)

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS

You can help improve this manual. If you find any mistakes or if you know of a way to improve the procedures, please let us know. Mail your letter or DA Form 2028 (Recommended Changes to Publications and Blank Forms), or DA Form 2028-2 located in back of this manual direct to Commander, US Army Communications and Electronics Materiel Readiness Command, ATTN: DRSEL-ME-MQ, Fort Monmouth, NJ 07703.

In either case, a reply will be furnished direct to you.

This manual is an authentication of the manufacturer's commercial literature which, through usage, has been found to cover the data required to operate and maintain this equipment. The manual was not prepared in accordance with military specifications; therefore, the format has not been structured to consider categories of maintenance.

SECTION 0. INTRODUCTION

Scope ...............................................................................................................................0-1 0-1

Indexes of Publications .....................................................................................................0-2 0-1

Maintenance forms, records, and reports...........................................................................0-3 0-1

Administrative storage.......................................................................................................0-4 0-2

Destruction of Army electronics materiel............................................................................0-5 0-2

Reporting of equipment improvements recommendations (EIR).........................................0-6 0-2

Items comprising an operable equipment ..........................................................................0-7 0-3

I. GENERAL INFORMATION

Introduction.......................................................................................................................1-1 1-1

Accessory equipment supplied..........................................................................................1-9 1-2

Instrument identification....................................................................................................1-11 1-2

150 BAL modification........................................................................................................1-13 1-2

II. INSTALLATION

Inspection.........................................................................................................................2-1 2-1

Warranty exception...........................................................................................................2-3 2-1

Power requirements..........................................................................................................2-5 2-1

Three-conductor power cable ............................................................................................2-7 2-1

Battery..............................................................................................................................2-10 2-1

Installation and removal of battery.....................................................................................2-12 2-2

Cover removal...................................................................................................................2-15 2-2

Repackaging for shipment.................................................................................................2-17 2-2

III. OPERATING INSTRUCTIONS

Introduction.......................................................................................................................3-1 3-1

Controls, connectors and indicators...................................................................................3-4 3-1

Operation..........................................................................................................................3-6 3-1

Battery..............................................................................................................................3-8 3-1

Level and noise measurements.........................................................................................3-12 3-5

Level measurements.........................................................................................................3-14 3-5

Noise measurements ........................................................................................................3-28 3-7

Recorder compatibility.......................................................................................................3-41 3-8

Applications......................................................................................................................3-45 3-8

Transmission loss measurements.....................................................................................3-48 3-10

Para Page

SECTION III. OPERATING INSTRUCTIONS (Cont.). Para Page

Crosstalk measurements...................................................................................................3-53 3-10

Identifying noise characteristics.........................................................................................3-57 3-10

Measurements in DBC ......................................................................................................3-64 3-11

Measurement procedures..................................................................................................3-67 3-12

150 BAL conversion..........................................................................................................3-69 3-12

IV. THEORY OF OPERATION

Introduction.......................................................................................................................4-1 4-1

Block diagram description.................................................................................................4-7 4-1

Detailed circuit description.................................................................................................4-16 4-2

Range attenuator A2.........................................................................................................4-18 4-3

Input amplifier A3..............................................................................................................4-20 4-3

Filters................................................................................................................................4-25 4-4

Meter amplifier..................................................................................................................4-30 4-7

Detector............................................................................................................................4-32 4-7

Power supply and series regulator.....................................................................................4-37 4-8

V. MAINTENANCE

Introduction.......................................................................................................................5-1 5-1

Factory selected values.....................................................................................................5-4 5-1

150 BAL conversion..........................................................................................................5-6 5-1

Performance Checks.........................................................................................................5-7 5-2

Adjustment and calibration procedure................................................................................5-14 5-8

Assembly removal.............................................................................................................5-25 5-10

Troubleshooting procedures..............................................................................................5-27 5-10

Factory selected values.....................................................................................................5-39 5-15

VI. REPLACEABLE PARTS

Introduction.......................................................................................................................6-1 6-1

Ordering information.........................................................................................................6-4 6-1

VII. CIRCUIT DIAGRAMS

Introduction.......................................................................................................................7-1 7-1

Functional block diagrams.................................................................................................7-3 7-1

Schematic diagrams .........................................................................................................7-5 7-1

APPENDIX A. REFERENCES.................................................................................................................. A-1

APPENDIX B. MAINTENANCE ALLOCATION

SECTION I. Introduction....................................................................................................................... B-1

Il. Maintenance allocation chart for Meter, Audio Level TA-885/U........................................... B-3

III. Tool and test equipment requirements for Meter, Audio Level TA-883/U ............................ B-4

IV. Remarks (Not applicable)

APPENDIX C. MANUAL BACKDATING CHANGES.................................................................................. C-1

Model 3555B Table of Contents

LIST OF ILLUSTRATIONS

Number Page Number Page 1-1.Model 3555B Transmission and

Noise Measuring Set..................................1-1 4-7.Simplified Peak Detection................................4-7

2-1.Power Plugs.................................................2-1 5-1.Balanced BNC to 310 Plug..............................5-2

3-1.Front Panel Controls, Indicators, 5-2.Level Accuracy Check.....................................5-2

and Connectors.........................................3-2 5-3.+20dBm and +30dBm Level

3-2.Side Panel Controls and Connectors.............3-4 Accuracy Check............................................5-4

3-3.Impedance Matching 3555B to Recorder......3-8 5-4.Return Loss Test Set-Up..................................5-5

3-4.Recorder Compatibility Chart........................3-9 5-5.Filter Response Test Set-Up............................5-5

3-5.Simplified Send/Receive Test Set-Up...........3-9 5-6.Bridging Loss Test Set-Up...............................5-6

3-6.Typical Test Set-Up for Measuring 5-7.Input Balance Test Set-Up...............................5-7

Insertion Loss..........................................3-10 5-8.Troubleshooting Tree.....................................5-11

3-7.Test Set-Up for Measuring 7-1.Functional Block Diagram..........................7-3/7-4

Crosstalk Coupling Loss..........................3-11 7-2.A1 Function Assembly Schematic and

3-8.Simple Test for Inductive and Component Location...............................7-5/7-6

Capacitive Coupling.................................3-12 7-3.A2 Range Attenuator and A3 Input

4-1.Simplified Block Diagram..............................4-1 Amplifier Schematic and Component

4-2.Simplified DIAL BAT Function......................4-2 Location..................................................7-7/7-8

4-3.Simplified NG Function.................................4-3 7-4.A4 Filter Schematic and Component

4-4. Simplified Average Detection........................4-4 Location................................................7-9/7-10

4-5.3kHz FLAT and PROGRAM 7-5.A3 Meter Amplifier, Detector and Series

Weighting Curves......................................4-5 Regulator Schematic and Component

4-6.C-MSG and 15kHz FLAT Locations............................................7-11/7-12

Weighting Curves......................................4-6

LIST OF TABLES

Number Page Number Page

1-1 Specifications...............................................1-0 5-1 Required Test Equipment................................5-1

1-2 Accessory Equipment Supplied.....................1-2 5-2 75 UNBAL Carrier Accuracy Check..................5-3

2-1 Suitable Batteries Meeting 5-3 Carrier 600 BAL and 135 BAL Level

NEDA 202 Specifications...........................2-1 Accuracy Check............................................5-3

3-1 Front, Side and Rear Panel Controls, 5-4 VF/Nm Level Accuracy Checks 600 BAL

Indicators and Connectors...................3-3/3-5 and 900 BAL -80 dBm Through +30 dBm.....5-4

3-2 Crosstalk Correction Factor........................3-10 5-5 Filter Response Checks...................................5-6

3-3 Level Measurement....................................3-13 5-6 Front Panel Trouble Analysis.................5-12/5-13

3-4 Noise Metallic Measurements.....................3-13 5-7 Function Troubleshooting...............................5-14

3-5 Noise-to-Ground Measurements.................3-14 5-8 FUNCTION Switch Resistance Values...........5-15

3-6 Balance Measurement................................3-14 5-9 Range Attenuation and Amplifier Gain...........5-16

3-7 Recorder Calibration...................................3-14 5-10 Resistance Checks........................................5-16

3-8 Transmission Loss Measurement................3-14 5-11 Factory Selected Values................................5-16

4-1 Range Attenuation and Amplifier Gain..........4-4 6-1 Replaceable Parts...........................................6-2

6-2 Part Number-National Stock Number

Cross Reference Index...............................6-10

iii

SECTION 0

INTRODUCTION

0-1. Scope

This manual contains instructions for the operation, organizational maintenance and general support maintenance of Audio Level Meter TA-885/U. Throughout this manual, the equipment is referred to by its commercial designation of Hewlett-Packard Model 3555B Transmission and Noise Measuring Set or simply as the 3555B. Appendix A of the manual contains a list of references and appendix B contains the maintenance allocation chart (MAC).

NOTE

No direct support maintenance functions are authorized for this equipment.

0-2. Indexes of Publications

a. DA Pam 310-4. Refer to the latest issue of DA Pam 310-4 to determine if there are any new editions, changes, or additional publications pertaining to this equipment.

b. DA Pam 310-7. Refer to DA Pam 310-7 to determine if there are any modification work orders (MWO's) pertaining to this equipment.

0-3. Maintenance Forms, Records, and Reports

a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and procedures used for equipment maintenance will be those described by TM 38-750, The Army Maintenance Management System.

0-1

b. Report of Packaging and Handling Deficiencies. Fill out and forward DD Form 6 (Packaging Improvement Report) as prescribed in AR 700-58/NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A, and DLAR 4145.8.

c. Discrepancy in Shipment Report (DISREP) (SF 361). Fill out and forward Discrepancy in Shipment Report (DISREP) (SF 361) as prescribed in AR 55-38/NAVSUPINST 4610.33B/AFR 75-18 MCO P4610.19C and DLAR 4500.15.

0-4. Administrative Storage

Before placing the TA-885/U in temporary storage (90 days), determine the serviceability of the equipment by performing the checks in paragraphs 5-7 through 5-13.

0-5. Destruction of Army Electronics Materiel

Destruction of Army electronics materiel shall be in accordance with the instructions in TM 750-244-2.

0-6. Reporting Equipment Improvement Recommendations (EIR)

If your TA-885/U needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tell us what you don't like about your equipment. Let us know why you don't like the design. Tell us why a procedure is hard to perform. Put it on an SF 368 (Quality Deficiency Report). Mail it to Commander, US Army Communications and Electronics Materiel Readiness Command, ATTN: DRSEL-ME MQ, Fort Monmouth, New Jersey 07703. We'll send you a reply.

0-2

0-7. Items Comprising an Operable Equipment

Audio Level Meter TA-885/U includes the meter, with cover and a power cord. The power cord is stored inside the cover of the set.

0-3

Section I Model 3555B

Table 1-1. Specifications

VOICE FREQUENCY LEVEL MEASUREMENTS (20Hz balanced and 75 ohms unbalanced. to 20kHz) Return loss: TERM ONLY

600 ohms: 26dB min 3kHz to 150kHz

Range: -91dBm to +31dBm 135 ohms: 26dB min to 600kHz

75 ohms: 30dB min to 3MHz

Level accuracy: 20Hz to 20kHz: +0.5dB Bridging loss: less than 0.05dB at 10kHz

40Hz to 15kHz: +-0.2dB Balance: (Levels greater than -60dBm) greater than 70dB to 10kHz

Note: For levels greater than +1 dBm, level accuracy greater than 60dB to 100kHz specification applies only for frequencies above greater than 40dB to 600kHz 100Hz.

GENERAL

Input: will terminate or bridge 600 ohms or 900 ohms Temperature range: 0°F to 120°F 0 to 95% relative

balanced. humidity Bridging loss: less than 0.3 dB at 1kHz. The 3555B will operate at -40°F under reduced Return loss: 30dB min. (50Hz to 20kHz) TERM specifications. At this temperature, attention Return loss: 30dB min. (50Hz to 2kHz) TERM should be given to noting condition of battery as

only. indicated on Battery Test (DIAL/BAT).

Balance:

greater than 80dB at 60Hz Meter: linear dB scale indicates rms value of input greater than 70dB to 6kHz signal. 12dB range. greater than 50dB to 20kHz Meter response

Holding circuit: 700 ohms dc resistance, 60mA Normal: 200ms to indicate a reading to 0dBm on

max. loop current at 300Hz. With holding circuit meter. in, above specs apply from 300Hz to 4kHz. Damp: 500ms to indicate a reading to 0dBm on

meter.

NOISE MEASUREMENTS

Maximum input voltage

Range: -1 dBm to +121dBm Tip to ring: 150V peak

Tip or ring to ground: 500V peak

Weighting filters: 3kHz flat, 15kHz flat, C-message, and (This is maximum instantaneous voltage. Input

program. Meets joint requirements of Edison circuit will withstand 48V dc CO battery with Electric Institute and Bell Telephone System. superimposed 90V rms 20Hz ringing voltage or

±130V carrier supply.)

Input: same as for level measurements.

Maximum longitudinal voltage: 200V rms at 60Hz

Noise to ground:

80 kilohms across line AC Monitor: 0.27V rms for 0dBm on meter. 100 kilohms to ground R

-40dB relative to 600 ohms noise metallic at jacks. Sufficient to drive WE 1011B or 52 type 1kHz. headset.

DC Monitor: 1 volt for 0dBm on meter. R

CARRIER FREQUENCY LEVEL MEASUREMENTS kilohms. Jack accepts 310 plug (tip negative). (30Hz to 3MHz)

Input jacks: will accept Western Electric (WE) 241,

Range: -61dBm to +11dBm 309, 310, 358 plugs. Binding posts accept banana Level accuracy: Removable shorting bar between sleeve and

600 ohms balanced ground binding posts. 1kHz to 150kHz: ±0.5dB Dial/AC Monitor jacks: will accept WE 289, 310, 347

135 ohms balanced (or 150 ohms balanced) plugs. Accepts WE 1011B lineman's handset or

1kHz to 600kHz: ±0.5dB 52 type headset. 10kHz to 300kHz: ±0.2dB

75 ohms unbalanced Power requirements:

100Hz to 600kHz: ±0.2dB Internal battery: single NEDA 202 45V "B" 30Hz to 1MHz: ±0.5dB battery included. Expected battery life - 180 1MHz to 3MHz: ±0.5dB ±10% of meter reading hours at 4 hours per day at 70° F.

in dBm. AC: 115V or 230V, 48-440Hz, <1W

Input: will terminate or bridge 600 ohms or 135 ohms accepts 310 plug (tip negative) less than 15mA.

= 8 kilohms. Available at DIAL/AC MON

out

= 2

out

plugs, spade lugs, phone tips or bare wires.

External battery: 24V or 48V office battery; jack

1-0

Model 3555B Section I

SECTION I

GENERAL INFORMATION

1-1. INTRODUCTION.

1-2. The Hewlett-Packard Model 3555 B Transmission and Noise Measuring Set is a versatile set designed for uses in testing telecommunications equipment. The extreme sensitivity of this set, linked with its wide and flat frequency response, make it suitable for noise and level measurements at voice, program and carrier frequencies. Levels from -80dBm to +30dBm (10dBm to +120dBm) full-scale can be measured and displayed on a meter calibrated to indicate both in dBm for level measurements and in dBm for noise measurements.

1-3. The set combines the features of a voice and noise frequency measuring set and the features of a carrier frequency measuring set. For voice and program frequencies impedances of 900 ohms and 600 ohms are

provided, balanced or unbalanced, bridged or terminated. For noise measurements a noise-to-ground (Ng) function is provided which provides 40dB of attenuation for longitudinal noise. For carrier frequencies 600 ohm, 135 ohm and 75 ohm impedances are provided. The 600 and 135 function can be either balanced or unbalanced, bridged or terminated; The 75 function is unbalanced only. Bridging impedance is over 100 kilohms, allowing measurements with a bridging loss of less than 0.05dB. The meter indicates in dBm for any selected input impedance.

1-4. The 3555B includes a 3kHz flat, a C-Message, a Program and a 15kHz flat filter, each easily selectable by a front panel control. These filters conform to the standards set up .by the Bell System and Edison Electric Institute. Other filters are available upon request.

Figure 1-1. Model 3555B Transmission and Noise Measuring Set

1-1

Section I Model 3555B 1-5. A noise-to-ground (Ng) function is included

which permits the measurement of longitudinal noise. When making noise-to ground measurements the impedance between INPUT terminals is greater than 80 kilohms and is 100 kilohms between each terminal and ground. A HOLD function permits holding the line while noise measurements are being made. The input circuitry provides 40dB of longitudinal noise attenuation when noise-to-ground measurements are being made.

1-6. A DIAL/BAT function permits connecting a lineman's handset to the line for the purpose of dialing and at the same time connects the front panel meter to the power supply so that the battery voltage or unregulated power supply voltage can be monitored.

1-7. Jacks accepting Western Electric type 241, 309, 310, 347, and 358 plugs are provided for INPUT connections to the 3555B. Dual binding posts accept banana plugs, wires, lugs or phone tips and a pair of special connectors permit the attachment of clip leads from a lineman's handset.

1-8. The Model 3555B can be operated from either the internal 45V dry cell battery or from the ac line, 115 or 230Vac, 48Hz to 440Hz. A special device is included in the cover to automatically turn the set off when the cover is replaced. The set can also be operated from the central office battery. A jack is provided on the side of the set for this purpose.

1-9. ACCESSORY EQUIPMENT SUPPLIED.

1-10. The accessory equipment supplied with the Model 3555B is listed in Table 1-2.

Table 1-2. Accessory Equipment Supplied

-hp- Part No. Description Quantity 8120-1348 Power Cord 1 1470-0026 Battery, 45 Volt dry cell 1 03555-26510 Test Board 1 5000-7135 Decal, 150 BAL 1

1-11. INSTRUMENT IDENTIFICATION.

1-12. Hewlett-Packard uses a two-section serial number. The first section (prefix) identifies a series of instruments. The last section (suffix) identifies a particular instrument within the series. If a letter is included with the serial number, it identifies the country in which the instrument was manufactured. If the serial prefix of your instrument differs from the one on the title page of this manual, a change sheet will be supplied to make this manual compatable with newer instruments or the backdating information in Appendix C will adapt this manual to earlier instruments. All correspondence with Hewlett-Packard should include the complete serial number.

1-13. 150 BAL MODIFICATION.

1-14. The Model 3555B is shipped from the factory with a 135 BAL function. If a 150 BAL function is desired instead of the 135 BAL function, the set can be converted by simply clipping a shorting wire within the set, applying a 150 BAL decal (supplied with the set) over the 135 BAL decal and making only one adjustment.

1-15. For detailed instructions on modification of the set refer to Paragraph 5-6. If your set is known to be within specification tolerances a simplified procedure can be used to modify the set and is described in Paragraph 3-69.

1-2

Model 3555B Section II

SECTION II

INSTALLATION

2-1. INSPECTION.

2-2. The set was carefully inspected both mechanically and electrically before shipment. It should be physically free of mars or scratches and in perfect electrical condition on receipt. To confirm this, the set should be inspected for physical damage in transit, for supplied accessories and for electrical performance. Paragraph 5-7 outlines the electrical performance checks using test equipment listed in Table 5-1. If there is damage or deficiency, see the warranty in the front of this manual.

2-3. WARRANTY EXCEPTION.

2-4. The battery supplied with the 3555B is warranted for a period of 60 days, beginning at the time of receipt of the set. This warranty is based on an expected battery life of 180 hours at 4 hours per day at 700 F as specified in Table 1-1 in this Manual.

2-5. POWER REQUIREMENTS.

2-6. This set is designed to operate from an internal 45 volt dry cell battery, an external 24 to 48 volt CO battery or from an ac power source (115/230V, 48 to 440Hz). The power source is selected by the AC/BAT switch on the side of the, set. The line voltage is selected by the 115/230 volt slide switch on the rear of the set. The set is protected by a 0.1 5A slow-blow fuse.

Table 2-1. Suitable Batteries Meeting

NEDA 202 Specifications

Manufacturer Mfr. Part No. Hewlett-Packard 1420-0026 Western Electric KS-14370 Military BA-59 Eveready 482 Burgess M-30 RCA VS013 Bright Star 3033-158, 30-33 Mallory M-202 Ray-O-Vac 202, P7830 Sears 6461 Wards 42 Wizard 3B6241 Zenith 2783 General W30B Marathon 4202 National Carbon 482

2-10. BATTERY.

2-11. This set is operated from a single NEDA 202 45V dry cell internal battery or an external 48V CO battery when the power selection switch, on the side of the case, is in the DIAL/BAT position. Inserting a Western Electric plug into the battery jack disconnects the internal battery. (See Table 2-1 for batteries suitable for use in this instrument.

2-7. THREE-CONDUCTOR POWER CABLE.

2-8. To protect operating personnel, the National Electrical Manufacturers' Association (NEMA) recommends that the panel and cabinet be grounded. This set is equipped with a three-conductor power cable which, when plugged into an appropriate receptacle, grounds the set. The offset pin on the power cable three-prong connector is the ground wire. This power cable is detachable from the set and is stored inside the front cover.

2-9. Figure 2-1 illustrates the standard power plug configurations that are used throughout the United States and in other countries. The -hp- part number shown directly below each plug drawing is the part number for a 3555B power cord equipped with the proper plug. If the appropriate power cord is not included with the instrument, notify the nearest HewlettPackard office and a replacement cord will be provided.

Figure 2-1. Power Plugs.

2-1

Section II Model 355B

2-12. INSTALLATION AND REMOVAL OF BATTERY.

2-13. To install or replace a battery, turn the four 1/4 turn fasteners on the battery cover on the rear of the case counterclockwise to remove the cover. Lift off the cover, lift the battery out of its recess and unplug the three-prong connector.

2-14. Reverse the above procedure when installing a new battery.

2-15. COVER REMOVAL.

2-16. To remove the cover from the instrument, release the two spring latches on either side of the instrument, then lift cover. When replacing the cover, first check the latches for released position; then place cover in position for latching. The power cord is stored inside the cover by wrapping it around the retainer fastened inside the cover.

CAUTION DO NOT FORCE COVER INTO PLACE. THERE IS A PROJECTION ON THE COVER WHICH TURNS THE POWER SWITCH TO THE OFF

POSITION TO PRESERVE BATTERY LIFE. IF THIS IS NOT BINDING, THE COVER FITS EASILY INTO PLACE.

2-17. REPACKAGING FOR SHIPMENT.

2-18. The following is a general guide for repackaging at instrument for shipment. If you have any questions, contact your local Sales and Service Office. (See Appendix for locations.)

a. Place instrument in original container if

available. If not available, one can be purchased from your nearest -hp- Sales and Service Office.

b. Wrap instrument in heavy paper or plastic

before placing in inner container.

c. Use plenty of packing material around all

sides of instrument.

d. Use a heavy carton or wooden box to

house the instrument and inner container and use strong tape or metal bands to seal the shipping container.

e. Mark shipping container with "Delicate

Instrument" or "Fragile".

2-2

Section III Model 3555B

SECTION III

OPERATING INSTRUCTIONS

3-1. INTRODUCTION.

3-2. The Model 3555B Transmission and Noise Measuring Set is an extremely versatile transmission and noise measuring set which satisfies many of the requirements in testing telecommunications equipment. The 3555B features a choice of 900 or 600 ohms bridging or terminated for voice frequencies and 600, 135 or 75 ohms bridging or terminate for carrier frequencies. Noiseto-ground and noise Metallic may be measured with 3kHz Flat, C-Message or 1 5kHz Flat weighting. A HOLD function permits seizing the line while measurements are being made at voice and program frequencies. The set is portable and operates from the internal battery, office battery or ac power source.

3-3. This section of the manual contains all the information necessary in the operation of the 3555B along with a description of all controls, connectors and indicators.

3-4. CONTROLS, CONNECTORS AND INDICATORS.

3-5. Figure 3-1, 3-2 and Table 3-1 illustrate and describe the function of all front and side panel controls, indicators and connectors.

3-6. OPERATION.

3-7. To operate the Model 3555B, refer to figure 3-1 and perform the following steps:

a. Before connecting the 3555B to an ac power

source, insure that the 115/230 volt switch is positioned to indicate the line voltage to be used. Some earlier instruments did not have the 115/230 volt selector switch. To change these instruments, jumper wires must be changed on the power transformer. Refer to Appendix C for a wiring diagram of the two configurations.

b. If the set is to be operated from the internal

battery or from an external office battery, place the AC/BAT switch (located on the side of the set) to the BAT position, using a small pointed object; if the set is to be operated from the ac line, place the AC/BAT switch to the AC position. For operation from a 24 or 48V office battery, connect a patch cord with a Western Electric 310 plug to the battery jack on the side of the case and then connect the cord to the office battery on the test board or bay. Inserting the plug disconnects the internal battery. The office battery is

arranged for -48V or -24V ±2V with the negative terminal of the battery connected to the tip and the ground terminal connected to the sleeve. Current consumption by the 3555B is approximately 15mA.

WARNING DURING BATTERY OPERATION, THE "G" BINDING POST MUST BE CONNECTED TO EARTH GROUND.

CAUTION THE CORD MUST BE CONNECTED TO THE MEASURING SET BATTERY JACK FIRST AND THEN PLUGGED INTO THE BATTERY SUPPLY TO AVOID SHORTING THE OFFICE BATTERY TO GROUND.

c. Turn the POWER switch to ON and depress

the DIAL/BAT pushbutton on the FUNCTION switch. The meter pointer should indicate in the BAT GOOD area indicating that the battery condition is good if the set is being operated from the internal battery. The meter will also monitor the ac supply voltage or the external office battery voltage, providing an indication of low voltage should it exist. The voltage should cause meter deflection above the lower end of the green BAT GOOD area for proper set operation.

3-8. BATTERY.

3-9. The internal dry cell battery has a voltage range between 45 volts when new to 24 volts at cut-off which is the end of useful life. The cut-off voltage corresponds to the left end of the green BAT GOOD area on the meter. The condition of the battery and the approximate time to cut-off can be estimated by observing the position of the meter pointer in the BAT GOOD area.

3-10. The internal battery is of the carbon-zinc type with its attendant limitations due to temperature. The service obtained from carbon-zinc batteries depends on factors such as current drain, discharge temperature, discharge time and storage prior to use. The battery supplied with the 3555B should provide in excess of 180 hours of operation based on a 4 hours/day duty cycle at 77° F (25° C). At other temperatures this time will change. At temperatures above 131° F (55° C) the batteries may fail suddenly while at temperatures below 40° F (-20° C), the service life will be short.

3-1

Section III Model 3555B

Figure 3-1. Front Panel Controls, Indicators, and Connectors

3-2

Model 3555B Section III

Table 3-1. Front, Side and Rear Pane

(1) S and G Jacks: Binding posts accepting banana

plugs, spade lugs, phone tips or bare wires for connection to the case ground (G) and sleeves (S) of all INPUT jacks (12) and DIAL/AC MON jacks (10) and (11).

(2) Shorting Strap: A swing-away shorting strap

connecting the S and G terminals together which may be used to isolate the jack sleeves from case ground. Not for use with type 347 plugs.

(3) WTG Switch: Selects weighting filters for noise

measurements. These filters are selectable only when the INPUT switch is in one of the two NOISE positions. The 3kHz FLAT, C-MSG, 15kHz FLAT and PROG filters all conform to the standards set up by the Bell System and Edison Institute for measuring message circuit noise.

(4) RANGE SWITCH: Selects dBm or dBm ranges of

input sensitivity. The RANGE switch markings correspond to the 0 markings on the meter scale (6). The black markings are dBm for transmission measurements and the blue markings are dBrn for noise measurements.

(5) RESPONSE Switch: Selects NORM meter

response for transmission level measurements or DAMP for noise measurements where noise is impulsive in nature.

(6) Meter: A taut band individually calibrated meter

with shaped pole pieces to provide a linear dBm indication with equal accuracy and resolution over the entire meter scale. The dBm scale is marked in black and has 0.1dB resolution for transmission measurements. The 0 marking at the right end of the scale corresponds to the black RANGE switch setting. The dBm scale is marked in blue for noise measurements. The 0 marking at the left end of the scale corresponds to the blue RANGE switch setting. The green arc marked BAT GOOD corresponds to the green DIAL BAT pushbutton for checking the power source. The left edge of the arc corresponds to the battery cut-off voltage of 24 volts and the right edge (meter full-scale) represents 60 volts which is the maximum voltage that can be used to power the set without internal damage.

(7) POWER ON/OFF Switch: turns on all power to the

set. The set operates from either 115 volts or 230 volts ac, the internal 45 volt dry cell battery or from an external office battery supply.

(8) INPUT Switch: Selects TMS, either BRDG or

TERM for transmission measurements and NOISE, either BRDG or TERM for noise measurements. For noise measurements the switch must be in

Controls, Indicators and Connectors either the NOISE BRDG or the NOISE TERM before the NOISE WTG filters can be selected.

(9) FUNCTION Switch: A series of interlocking

pushbutton switches (with the exception of the HOLD switch which is push-push type) with the following functions:

a. VF/Nm

1. HOLD: Applies a dc holding bridge across the metallic line for the NG, 900 and 600 functions. The HOLD pushbutton is the push-push type, ie, push to make and push to break. The HOLD function cannot be accomplished when any one of the CARRIER pushbuttons is depressed.

2. DIAL/BAT: Connects the multiple INPUT jacks in parallel with the DIAL/AC MON jacks for the dial and talk operation. The circuit is arranged for loop dialing and the line under test must supply talk battery. Connects the meter circuit and a load to the internal power supply to check the condition of the battery, ac power or external office battery as indicated on the green meter scale. POWER (7) must be ON for the battery test.

3. NG: Selects the noise-to-ground input circuits for measuring longitudinal noise. Attenuation of 40dB is inserted by this circuit. Earth ground should be connected to the black G binding post (1)

4. 900: Selects the input circuitry for balanced 900 ohm circuits. This function selects a low frequency transformer for voice frequencies. Response of this transformer is 20Hz to 20kHz.

5. 600: Selects the input circuitry for balanced 600 ohm circuits. A low frequency transformer is selected for this function.

b. Carrier

1. 600: Selects the input circuitry for balanced 600 ohm circuits. A high frequency transformer is selected for this function. Response of this transformer is 1kHz to 600kHz. The HOLD function is not operative in any of the carrier functions.

3-3

Section III Model 3555B

Figure 3-2. Side Panel Controls and Connectors

3-4

Model 3555B Section III

Table 3-1. Front, Side and Rear Panel Controls, Indicators and Connectors (Cont’d)

2. 135: Selects the input circuitry for 135 ohm balanced circuits. A high frequency transformer is selected for this function.

3. 75: Selects the input circuitry for 75 ohm unbalanced operation. Only the 75 ohm jack can be used for this function. This function does not utilize an input transformer, therefore the maximum bandwidth is available on this function. This jack accepts a 358 plug.

(10) DIAL/AC MON: A set of multiple jacks accepting

Western Electric type 310 or 347 plugs, 289 dual plugs and a pair of special clip posts marked T and R which accept a Western Electric 1011IB lineman's handset for the dial and talk operation when the FUNCTION pushbutton marked DIAL/BAT is depressed. Loop dialing is used and the circuit must supply talk battery. When any other FUNCTION pushbutton is depressed, the tip and ring of these jacks are connected to the AC MON output of the internal amplifiers for monitoring purposes.

(11) DC MON: Accepts a Western Electric 310 or 347

plug for tip negative and sleeve connections to an external dc recorder. Output voltage is proportional to the input voltage on any one setting of the RANGE switch.

(12) INPUT: A set of multiple jacks accepting Western

Electric 241 (or 289), 309, 310 and 358 plugs and a pair of binding posts marked T and R for banana plugs, spade lugs, phone tips or bare wires

providing connection to the input circuitry of the measuring set. When the DIAL BAT pushbutton is depressed, the INPUT jacks are connected in parallel with the DIAL/AC MON jacks.

(13) Battery Cover: Removeable by four 1/4 turn screw

fasteners to expose the internal battery for replacement.

(14) 48V 310: A jack accepting a Western Electric 310

plug with tip negative and sleeve ground to supply external office battery power to the set. Insertion of a 310 plug into this jack disconnects the internal battery. The BAT-AC switch (16) must be set to BAT for office battery operation.

CAUTION WHEN OPERATING FROM AN EXTERNAL BATTERY, CORD SHOULD BE CONNECTED TO MEASURING SET FIRST, THEN PLUG INTO BATTERY SUPPLY TO AVOID SHORTING THE OFFICE BATTERY.

(15) 0.15A-SPARE Fuse: A 0.15A slo-blo fuse and a

spare for measuring set protection when operating from AC power. Fuses are not used when the set is battery powered.

(16) BAT-AC Switch: A slide switch for selecting the ac

power source or the internal battery and office battery jack, (14), power source. The switch may be operated by a small screwdriver or pointed tool inserted into the slot in the switch.

(17) AC Power Receptacle: A 3 prong power receptacle

for the special power cord stored inside the front cover. The BAT-AC switch (16), must be positioned to AC for this power source.

3-11. High storage temperature is damaging to dry cells and tends to reduce shelf life. Low storage temperature is beneficial to battery life although the battery should be warmed to room temperature prior to use. Turning off the set when not in use and consideration of the above factors will maximize battery life. The instant turn characteristics of this set with no warm-up time required allows turning off between measurements.

NOTE If the battery voltage indication drops below the left end of the arc on the meter face the set will not operate properly. This will be noted by a slow oscillation of the meter. If this symptom is encountered, depress the DIAL/BAT pushbutton and check the battery condition. If the indication is to the left of

the arc on the meter face, replace the battery.

3-12. LEVEL AND NOISE MEASUREMENTS.

3-13. Since the 3555B is both a level measuring set and a noise measuring set, the procedure for making these measurements will be treated separately. Level measurements can be made at voice frequencies and carrier frequencies. Since the procedure for making voice and Carrier level measurements are identical except for the FUNCTION pushbutton utilized, only one procedure will be described in detail.

3-14. LEVEL MEASUREMENTS.

3-15. The 3555B can be used as a wide range and wide

3-5

Section III Model 3555B frequency Transmission Measuring Set (TMS) for voice, program and carrier multiplex measurements. The set will operate over a wide range of environmental conditions and maintain a high degree of accuracy. 3-16. In general, transmission level measurements are made by connecting the circuit under test to the INPUT jacks with a suitable patch cord, selecting the proper bridging or terminate condition and impedance, and then operating the RANGE switch to provide an on-scale meter indication. Transmission level measurements are made with the INPUT switch in TMS position either bridging or terminated. In this position, the set has its maximum frequency range. 3-17. The multiple INPUT jacks and binding posts accept the Western Electric 309, 310 and 358 single plugs and the 241 or 289 twin plug. The two red binding posts marked T (tip) and R (ring) will accept banana plugs, spade lugs, phone tips or bare wires. These jacks and binding posts are all connected in parallel and only one should be used at a time. A patching cord such as the Western Electric 3P12H, consisting of a cord with a 310 plug on one end and a 309 plug on the other end, should be kept with the instrument as a universal patch cord. The 75 ohm jack accepts Western Electric type 358 plugs for 75 ohms. unbalanced carrier measurements. 3-18. The sleeves of all the INPUT and DIAL jacks are connected together and to the black binding post marked S. The binding post in turn, is connected through a swingaway shorting strap to a second black binding post marked G. This binding post is the measuring set case ground. When it is necessary to establish a battery or ground connection on the sleeve for PBX test purposes, this shorting strap may be disconnected by loosening the black binding posts and swinging away the strap. A cord is then connected to the S terminal and may be connected to the battery or ground for the test. Type 347 plugs must not be used when the shorting strap is removed. 3-19. The multiple jacks marked DIAL/AC MON are connected in parallel and accept a 310 or a 347 single plug or a 289 dual plug. A dial with the impulse springs connected to the tip and ring of a 310 or 347 plug may be used or a lineman's handset such as the Western Electric 1011 B may be connected to the two square clip posts for the dialing and talk operation. When the FUNCTION pushbutton marked DIAL/BAT is depressed, the DIAL jacks are connected to the INPUT jacks and a number may be dialed on the line connected to the INPUT jacks. The circuit is arranged for loop dial operation and the circuit under test must supply talk battery. 3-20. Once the switching equipment has been seized by the dialing operation, the connection can be held by depressing the HOLD pushbutton. This places a dc bridge consisting of a high impedance retardation coil, across the INPUT terminals. This coil has negligible effect on measurements of voice frequencies. Once any other pushbutton is depressed, the AC output of the internal amplifier circuit is returned to the DIAL/AC MON jacks for an external head Model 3555B phone which can be used to monitor the noise or tones being measured. The

lineman's hand set which was used for the dialing operation can be used for monitering by leaving it connected to the clip posts. The jacks marked 310 will accept a head phone or recorder connected to the tip and ring of a 310 plug or tip and sleeve of a 347 plug. The performance of the set is not affected by this output and any impedance head-phone may be used. 3-21. The DIAL/BAT function also checks the power source used. The green arc on the meter marked BAT GOOD corresponding to the green BAT marking on the pushbutton, indicates the range of voltages for proper operation. Full scale corresponds to 60 volts and the left end of the arc corresponds to the battery cut-off voltage of 24 volts. Thus the remaining battery life can be estimated by noting the position of the pointer in the green arc. Since the set POWER must be turned ON to perform this check, the battery is properly loaded to give a true indication of its condition. When operating from the external office battery or AC power, the meter monitors this voltage to indicate if it is the correct level to properly power the set. The POWER switch turns OFF and ON all power to the set. 3-22. The remaining FUNCTIONS are used to set up the input conditions. The Ng function will be discussed under the paragraph heading, "NOISE MEASUREMENTS". The impedance of the set is selected by the pushbuttons marked 900 and 600 for voice frequencies and 600, 135 and 75 for carrier frequencies. The 900 and 600 ohm impedances are normally used for loop plant testing while 600, 135 and 75 ohms are usually reserved for carrier system measurements. A bridged or terminated condition is determined by the position of the INPUT switch. Using this procedure, the meter will always indicate in dBm for the impedance selected, bridging or terminated. The terminations, when used, are provided with a dc blocking capacitor. Accidental application of carrier or telegraph battery, office battery or ringing voltage will not damage the set. The pushbutton marked HOLD bypasses the INPUT switch and terminates the circuit in addition to placing the holding bridge across the line that is connected to the INPUT. When the INPUT switch is in either of the NOISE positions, weighting filters can be selected by the NOISE WTG switch for noise measurements. 3-23. The RANGE switch selects the dBm range of the meter. To avoid overloading the set, turn the RANGE switch to +30dBm when connecting a circuit for testing. Once the circuit connection is established turn the RANGE switch counterclockwise until an on-scale indication is obtained. The black dBm marking on the RANGE switch identifies the input level required to deflect the meter to the 0 mark on the black scale. The meter uses shaped pole pieces to present linear dBm markings on the scale with marks at 0.1 dBm increments. The accuracy and resolution of this type of meter is the same at any point on the scale and it is not necessary to keep the pointer in the upper portion of the scale for maximum accuracy. The accuracy of the set is not affected by the position of the set. This type of meter will have the pointer off-scale to the left

3-6

Model 3555B Section III when no input signal is present and a mechanical zero

adjust is not required. The actual input level to the set is the algebraic sum of the black dBm meter scale and black RANGE setting. For example, RANGE is set to 40dBm and the meter indicates -6.3dBm. The input level is then (-

40) + (-6.3) = -46.3dBm. If the RANGE switch is at +20dBm and the meter indication is 4.7dBm, the level is (+20) + (4.7) = +15.3dBm. 3-24. All panel markings corresponding to the proper dBm markings on the RANGE switch and meter face are in black, as is the TMS position of the INPUT switch. The blue markings correspond to the settings for noise measurements as discussed in paragraph 3-28. The response of the meter rectifier circuit is RMS which allows the set to measure the true power of any arbitrary input waveform provided the crest factor does not exceed 4:1. Crest factor is defined as the ratio of the peak value of the waveform to the RMS value of that waveform. In most telephonic measurements, consideration of this crest factor is not necessary. 3-25. The balanced input to the set is achieved through the use of two repeat coils, one for voice frequencies from 20Hz to 20kHz and the other for carrier frequencies from 10kHz to 600kHz. The maximum high frequency range is achieved through the use of the 75 ohm functions and the 75 ohm jack. This input bypasses both input repeat coils, thus allowing measurements from 30Hz to 3MHz. This high frequency range is limited to 600kHz on the +20 and +30dBm ranges. The maximum longitudinal input voltage is 150 volts peak between tip and ring and 200 volts rms at 60Hz between either tip or ring and ground. 3-26. The switch marked RESPONSE determines the speed of the meter response and is usually left in the NORM position for transmission measurements. 3-27. The jack marked DC MON accepts a Western Electric 310 or 347 plug with connections to the tip and sleeve. The dc voltage supplied by this jack can be used to operate a dc potentiometric recorder requiring 1V or a dc galvanometric recorder requiring 500uA. The dc output is proportional to input level on any one range and not meter deflection since the meter is logarithmically scaled. Knowing the current required to drive the recorder full scale and the input impedance of the recorder, enter these numbers into the recorder compatability chart Figure 3-4 to determine if the recorder is suitable for use with this set. If these numbers do not fall within the compatability area, refer to Paragraph 3-41. Connect an input voltage to the set and adjust the RANGE switch until a near full scale indication is observed on the meter. Connect the recorder plug with the tip negative to the DC MON jack and adjust the input level until the meter indicates 0dBm. Mark this point, which should be near full scale, on the recorder paper. Decrease the input level until the meter indicates 1dBm. Mark this point on the recorder paper. Continue until the recorder has been calibrated for each major dBm division on the meter. The actual input level to the set as

indicated on the recorder will be the algebraic sum of the RANGE.

3-28. NOISE MEASUREMENT.

3-29. One of the primary functions of this set is to measure message circuit noise, both metallic and noise-toground. The weighting filters built into this set are switch selected and their characteristics conform to the standards set up by the Bell System and Edison Electric Institute. 3-30. In general, noise-metallic measurements are made by connecting the circuit under test to the INPUT jacks with a suitable patch cord, selecting the proper bridging or terminate condition and impedance, selecting the proper weighting filter and operating the RANGE switch to provide an on-scale meter indication. Noise measurements involve many of the same operations as the level measurements discussed in Paragraph 3-14 and only the differences will be discussed. 3-31. Four filters are supplied for noise measurements; C-MESSAGE and 3kHz FLAT for message circuit noise measurement, a PROG and 15kHz FLAT for broadcast studio-transmitter links and telephone company program circuits. These filters are necessary to allow the measuring set to approximate the response of the human ear and give an indication representative of a person's subjectiveness to noise. The frequency response of these filters is shown in Figures 4-5 and 4-6. 3-32. Once a circuit has been connected, the RANGE switch is adjusted until the noise fluctuations appear onscale on the meter with normal response, and a two-tothree minute observation of the pointer fluctuations is made to establish the point at which the pointer appears most of the time, disregarding the occasional high peaks. For rapidly fluctuating noise such as atmospheric static or switching noise, operate the RESPONSE switch to DAMP. In this position of the switch, the level of the most frequently occurring peaks should be read. Noise is specified in dBm (decibels above reference noise) and the type of filter used is noted, for example, dBmC meaning C-message weighting is used. 3-33. The noise-metallic level is the algebraic sum of the indication on the blue dBm meter scale and the blue dBm RANGE switch setting. For example, RANGE is set to 20dBm and the meter indicates +7dBm. The noisemetallic level is (20) + (+7) = +27dBm. The RANGE switch marking indicates the level at the 0dBm mark on the left end of the meter scale. 3-34. Occasionally other message circuit weightings such as the older Bell System F1A weighting or the International Telecommunication Union's CCITT or psophometric weighting may be required. To convert from C-message to F1A, subtract 6dBm from the C-message indication. The units for F1A weighting are dBa, meaning decibels adjusted. To convert from C-message to CCITT or psophometric weighting, subtract 1dBm from the Cmessage level as read on the black dBm meter scale and RANGE switch setting. This will give the noise level in dBm which is acceptable for psophometric measurements.

3-7

Section III Model 3555B 3-35. As an aid in identifying the source of noise, the DIAL/AC MON jacks can be used with a monitoring receiver to listen to the noise which will have approximately the same quality as that heard by a subscriber. Particular types of noise like power line induction, switching noise, atmospheric static, crosstalk or random noise may be identified by this listening test. To aid in bringing up the level of the lower frequency power line noise, the 3kHz flat weighting is used. A substantial increase in meter indication with the 3kHz flat weighting indicates the presence of low frequency noise and it will also sound louder in the monitoring headphone. 3-36. In some cases recording of the noise during a busy period is necessary. The recorder connections and operation is discussed in Paragraph 3-27. The calibration should be done using the dBm scale rather than the dBm scale and it should be noted that the RESPONSE switch also damps the recorder. 3-37. Noise-to-ground measurements are made by a special input circuit arrangement which is used when either the Ng or Ng HOLD pushbutton is depressed. Dial and talk may be accomplished on the metallic circuit and the metallic connection held by using the Ng HOLD pushbutton. It is necessary to establish a good earth or system ground and connect it to the black binding post marked G. The noise-to-ground measurement is 40dB less sensitive than the noise metallic measurement because of the voltage divider in the input circuit. This requires adding 40dB to the meter indication to arrive at the correct noise-to-ground level. The level is the algebraic sum of the blue RANGE switch setting and the blue meter scale indication plus 40dB. For example, RANGE is set to 20dBm and the meter indicates +3dBm.

3-40. Crosstalk measurements involve low level measurements and part of the meter indication may be 38 Model 3555B caused by noise in addition to crosstalk. The general technique is to measure with crosstalk and noise present and then measure noise alone. A correction factor must then be applied and can be found in Table 3-2.

3-41. RECORDER COMPATIBILITY.

3-42. If an external recorder is to be used to monitor the dc output of the 3555B, the Recorder Compatibility graph, Figure 3-4 should be consulted to determine if your particular recorder can be used. Recorders with input characteristics that fall below the compatibility area can be used provided a suitable resistor is used between the 3555B dc output and the recorder input. 3-43. To choose the value of this resistance, simply follow the line designating the full scale current of your recorder, horizontally until it intersects the top line in the Recorder Compatibility graph. From this intersection follow the vertical line to find the total impedance RT required for full scale deflection (see Figure 3-3). The input impedance of the recorder should be subtracted from this value RT to determine the value of R1. For example, assume that your particular recorder has an input impedance of 2000 ohms with a full scale sensitivity of 20uA. Follow the 20uA line to the right until it intersects the top line at 48 kilohms. The value of R1 will then be 48 kilohms -2 kilohms input impedance = 46 kilohms. 3-44. Recorders with input characteristics that fall above the compatibility area in Figure 3-4 cannot be used to monitor the 3555B dc output since full scale deflection

of the recorder cannot be accomplished by the 3555B. The noise-to-ground level is 20 + (+3) +40= 63dBm. Some telephone company operating procedures disregard the 40dB correction factor in which case the noise-toground level would be 20 + 3 = 23dBm. 3-38. The Nm and Ng indications can be used to compute the balance of a facility since balance is defined as the degree of rejection of longitudinal signals. The degree of balance in dB where the major part of noisemetallic is due to noise-to-ground, is given by the

Figure 3-3. Impedance Matching 3555B to Recorder

equation, Balance in dB = Nm - Ng. For example, if the noise-metallic level of a circuit is +26dBm and the noiseto-ground of the same circuit is +9OdBmC, the balance in dB is (+26) - (+90) = 64dB. In the case mentioned above where the 40dB correction factor is neglected, the balance in dB = (Nm) (Ng + 40). 3-39. Other general purpose uses of the 3555B are volume and crosstalk measurements. The ballistic characteristics of the set make it approximately correct for VU measurements. The RANGE switch should be adjusted until the meter pointer fluctuations are on-scale and should be observed for the maximum of the frequently occurring peaks, disregarding the occasional high peaks. The meter indication in dBm is equal to VU (volume units.)

3-45. APPLICATIONS.

3-46. Sometimes it is necessary to transmit or send a

tone on a line and then measure the received signal

coming back on the same line. Rather than change

connections back and forth between the 3555B and 236A

Oscillator when changing from SEND to RECEIVE and

thus take a chance on dropping the line, it is much more

convenient to make one set of connections and then

select SEND or RECEIVE by means or a switch. Refer to

Figure 3-5.

3-47. By utilizing the test set-up shown in Figure 3-5,

send and receive can be accomplished with a minimum

number of operations. To dial, set both function switches

to DIAL and dial the desired line on the butt-in. To send,

change the

3-8

Model 3555B Section III

Figure 3-4. Recorder Compatibility Chart

Figure 3-5. Simplified Send/Receive Test Set-up

3-9

Section III Model 3555B 236A FUNCTION switch to 600 HOLD or 900 HOLD,

depending on the impedance required. To receive a tone, set the 3555B FUNCTION switch to either 600 HOLD or 900 HOLD (whichever is appropriate) and change the 236A FUNCTION switch to DIAL. To send again, simply change the 236A to 600 HOLD or 900 HOLD. If holding is not required or dialing is not required, simply select the impedance and switch back and forth on the 236A FUNCTION switch.

3-48. TRANSMISSION LOSS MEASUREMENTS.

3-49. Transmission loss is defined as the ratio of power from a transmission line by a receiving terminal to the power available from the sending equipment and is dependent on three factors; power dissipated by the dc resistance of the line, power losses because of impedance mismatch, power transferred to other circuits by inductive or capacitive coupling. (See Figure 3-6). 3-50. These factors are difficult to measure separately. Their sum, however, is relatively easy to measure with the -hp- 236A/3555B combination. 3-51. Figure 3-6 shows a typical transmission loss measurement setup. The oscillator is adjusted for a reference level and the signal is measured at the other end of the line with a level meter. Loss measurements are usually made at various frequencies to determine the response of the line. 3-52. Ideally the man at each end of the line will have both an oscillator and a Transmission Measuring Set (TMS) so that the loss can be measured in both directions, If the line that is being tested passes through central office switching equipment, the oscillator or TMS at the remote end is placed in the DIAL mode and the lineman's handset connected to the DIAL posts, permitting the repairman to bypass the instrument circuitry and dial his test board at the central office. Tests are then made in the 600 or 900 ohm HOLD positions, which provide a dc path to hold the switching relays.

3-53. CROSSTALK MEASUREMENTS.

3-54. Crosstalk is interference on a transmission line caused by inductive and capacitive coupling between pairs of transmission lines in close proximity. Crosstalk can be classified as near-end and far-end. Far-end crosstalk is interference at the end of the transmission line opposite the , signal source while near-end crosstalk is interference detected at the same end of the line as the signal source.

Table 3-2. Crosstalk Correction Factor

dB Correction Factor

(Crosstalk + Noise) in dB Crosstalk in dB =

Minus Noise Alone in dB (Crosstalk + Noise)

Minus Correction Factor 1 7 2 4 3 3 4 to5 2 6 to 8 1 9 and above 0

3-55. Since different frequency bands are used for each direction of transmission on two wire carrier systems, near-end crosstalk cannot be detected. The situation is quite different, however, for far-end crosstalk since it is in the same frequency band as the desired signal and can be detected. 3-56. Referring to Figure 3-7, one line is designated A-B and the other designated C-D with A and C representing the near-end of one of the pairs, and band D representing the far-end of the other pair. First measure the transmission loss between A and B. Then measure the transmission loss from A to D. The crosstalk coupling loss in dBx is the difference in the reading from A to B and the reading from Ato D.

3-57. IDENTIFYING NOISE CHARACTERISTICS.

Figure 3-6. Typical Test Setup for Measuring Insertion Loss

3-10

Model 3555B Section III

Figure 3-7. Test Setup for Measuring Crosstalk Coupling Loss

3-58. Normally, a frequency selective voltmeter is used to identify the characteristics of transmission line interference in order to trace it down to its origin and apply the appropriate corrective action. As an expedient for troubleshooting, there are several subjective measurements that the 236A/3555B can make to help identify the interference characteristics. 3-59. Since power line noise is the most common nuisance, a quick check with the 3555B should be made first. By noting the difference in noise readings between the 3kHz FLAT and C-message weighted modes, an indication of line frequency disturbance can be ascertained if the 3kHz flat mode shows a substantially higher reading. 3-60. As a further aid in identifying noise, the lineman's handset can be connected to the AC MONITOR terminals and an aural analysis made. Although the handset will not respond to 60Hz, line interference is usually very rich in odd harmonics and 180Hz can easily be identified. This test also helps to identify "babble" and other audio frequency interference. 3-61. Vagrant noise, such as atmospheric noise, can be analyzed by connecting a strip chart recorder to the DC MONITOR terminals. Long-term seasonal and temperature effects can also be measured very conveniently with a recorder. 3-62. Frequency of strong interfering periodic signals, such as radio transmitters, can be roughly determined with the 236A and 3555B. The 236A is connected to one end of the line and the 3555B to the remote end, as with transmission loss measurements. The oscillator output is increased until the test meter barely indicates a signal above the noise. The oscillator frequency is then changed very slowly while the repairman observes the 3555B for a beat. By tuning for a beat, the frequency of

oscillator frequency dial to an accuracy of approximately ±3%. In practice, this measurement would probably be made using a "loop around" technique. The oscillator would be connected to a quiet line at the remote location and this line would be tied to the noisy line back at the central office. This permits one man to operate both the oscillator and the test meter. 3-63. When a current flows through a conductor, it sets up two distinct fields around the conductor - - the electrostatic (capacitive) field and the magnetic (inductive) field. Both are capable of inducing longitudinal voltages in adjacent conductors, and both increase in proportion to the power and frequency of the current from which they result. They differ greatly, however, in how they affect nearby circuits. The voltage resulting from magnetic induction varies inversely-with the impedance of the line. That is, the higher the line impedance, the less voltage that can be induced by a magnetic field. Capacitively coupled voltage, on the other hand, increases in direct proportion to line impedance-- the higher the impedance, the greater the capacitive coupling. By means of a simple test, it is possible to identify the coupling between two lines, as shown in Figure 3-8. Since induced voltages are inversely proportional to line impedance, the voltage coupled from pair A into pair B (Figure 3-8a) will increase as the impedance is lowered (i.e., shorted). Conversely, since capacitively coupled voltages are directly proportional to impedance, the coupled voltage in Figure 3-8b would increase as the impedance is increased (i.e., open circuited). Both tests in Figure 3-8 should be performed to correlate the result.

3-64. MEASUREMENTS IN DBC.

3-65. The term dBC means dB Collins and is defined as

the interfering signal can be read directly off the

3-11

Section III Model 3555B

Figure 3-8. Simple Test for Inductive and Capacitive Coupling

0dBC = 0.775V across any impedance as read on an

-hp- Model 400D AC Vacuum Tube Voltmeter. Thus, the dBC is strictly a relative term. 3-66. Measurements can easily be made in dBC. by utilizing the Model 3555B Telephone Test Meter. To make these measurements, set FUNCTION to 600 and the INPUT switch to TMS BRDG. Any termination required other than 600 ohms must be provided externally and connected across the two binding posts T and R. Termination can also be made using a patch cord and any one of the other INPUT jacks since all INPUT jacks are connected in parallel. If a 600 ohm termination is to be used, the internal termination can be utilized by placing the INPUT switch to the TMS TERM position.

3-67. MEASUREMENT PROCEDURES.

3-68. Tables 3-3 through 3-8 list the step by step procedures for measuring levels and noise balance, recorder calibration and transmission loss using the 3555B. For a more detailed discussion on level and noise measurements refer to paragraphs 3-12 through 3-47.

3-69. 150 BAL CONVERSION.

3-70. The 3555B comes equipped with all the necessary parts for converting the 135 BAL function to a 150 BAL function. The following is a simplified procedure for making the modification.

a. Remove the set from the case and remove

the FUNCTION board. Clip the shorting wire from across A1R17 (see Figure 7-2) and reinstall the FUNCTION board. Leave the set out of the case.

b. Set the 3555B controls as follows:

RANGE..........................................0dBm

FUNCTION................................135 BAL

INPUT ..................................TMS TERM

c. Remove the 150 BAL decal from the

envelope supplied with the set. Remove the backing from the decal and place it over the 135 BAL function pushbutton.

d. Connect a 150 ohm balanced source to the

input of the 3555B at a level of 0dBm (387mV rms) at a frequency of 1kHz. Turn the 3555B ON and adjust A3R24 (Figure 7-

3) for 0dBm indication on the 3555B meter.

e. Reinstall the set in its case.

3-12

Model 3555B Section III

Table 3-3. Level Measurement

STEP PROCEDURE

1. Turn the 3555B/ON and depress the DIAL/BAT pushbutton. The meter should indicate in the green BAT GOOD area. If it does not, replace the battery or check the power source before attempting to make any measurements. The battery test operates for internal battery, office battery or ac power source.

2. Select either TMS BRDG or TMS TERM, depending on the measurement being made. The weighting filters are not in the circuit at this time.

3. Select the impedance (FUNCTION pushbutton) to match the circuit to be tested. Select either 900 BAL or 600 BAL (VF/Nm) for frequencies between 20Hz and 20kHz. Select 600 BAL or 135 BAL (CARRIER) for balanced measurements between 1 kHz and 600kHz. Select 75 UNBAL for 75 ohm unbalanced measurements between 30Hz and 3MHz.

4. Set the RANGE switch to +30dBm. Set the RESPONSE switch to DAMP.

5. Connect the set to the line using a suitable patch cord. For balanced measurements use a cord having a 309 or 310 single plug, a 241 dual plug or banana plugs, bare wires or clip leads. For unbalanced carrier measurements (75 ohm only) use a cord having a 358 plug.

NOTE Carrier measurements are limited to the -50dBm RANGE thru the +10dBm RANGE.

6. Down range the RANGE switch for an onscale indication. Level is equal to the algebraic sum of the black RANGE setting plus the black meter scale indication.

Table 3-4. Noise Metallic Measurements

STEP PROCEDURE

1. Turn the POWER switch to ON and depress the DIAL/BAT pushbutton. The meter should indicate in the green BAT GOOD area. If it does not replace the battery or check the power source. The battery test operates on internal battery, office battery or ac power source.

2. Select either NOISE TERM or NOISE BRDG, depending on the measurement being made.

3. Select the impedance to match the circuit to be tested using the FUNCTION pushbuttons. The 900 BAL VF/Nm pushbuttons only should be used for noise metallic measurements in the frequency range of 20Hz to 20kHz. The HOLD function can be used in NOISE TERM if desired.

4. Select the appropriate weighting filters using the NOISE WTG switch.

5. Set the RANGE switch to 110dBrn.

6. Connect the set to the circuit to be tested using a suitable patch cord and down range for an on-scale indication.

7. Observe the meter fluctuations for two or three minutes and take a reading where the meter pointer appears to be most of the time, disregarding any occasional peaks.

NOTE For rapidly fluctuating noises such as atmospheric noise or switching noise, operate the RESPONSE switch to DAMP and read the level of the most frequently occurring peaks.

8. Noise level is equal to the sum of the blue RANGE switch setting in dBrn and the indication on the blue meter scale in dBrn.

EXAMPLES:

RANGE = -50dBm METER = +1dBm LEVEL = -49dBm

RANGE = +20dBm METER = -4dBm LEVEL = +16dBm

EXAMPLE:

RANGE = 40dBrn METER = +5dBrn NOISE LEVEL = +45dBrn

3-13

Section III Model 3555B

Table 3-5. Noise-to-Ground Measurements

STEP PROCEDURE

1. Turn the 3555B POWER switch to ON and depress the DIAL/BAT pushbutton. The meter should indicate in the green BAT GOOD area. If it does not replace the battery or check the power source. The battery test operates for internal battery, office battery or ac power source.

2. Set the INPUT switch to NOISE BRDG.

3. Select the appropriate weighting filter using the NOISE WTG switch.

4. Set the RANGE switch to 110dBrn.

5. Depress the NG pushbutton and connect the set to the circuit to be tested. Down range for an on-scale indication.

NOTE Dial and talk may be accomplished on the metallic circuit and the connection held by depressing the HOLD pushbutton.

Table 3-6. Balance Measurement

STEP PROCEDURE

1. Perform the Noise-to-ground measurement as described in Table 3-5.

2. Perform the Noise Metallic measurements as described in Table 3-4.

3. Compute the line balance in dB using the results of the above checks.

Balance (dB) = Nm - NG

EXAMPLE:

Noise-to-ground = +26dBrn Noise Metallic = (-)+90dBrn Balance in dB = -64dBm

NOTE The noise-to-ground measurement above includes the 40dB correction factor.

Table 3-7. Recorder Calibration

STEP PROCEDURE

1. Determine the input impedance and full scale sensitivity of your recorder and refer to paragraph 3-41 and Figure 3-4 to determine if your recorder is suitable for use with this set. The dc voltage supplied by the DC MON 310 jack will drive a dc potentiometric recorder requiring 1V or a dc galvanometric recorder requiring 500uA.

2. Connect an input voltage to the set and adjust the RANGE switch until a near full-scale indication is observed on the meter.

3. Connect the recorder plug with the tip negative, to the DC MON jack and adjust the input level until the meter indicates 0dBm. Mark this point on the recorder paper which should be near full scale.

4. Decrease the input level to the set until the' meter indicates -1dBm. Mark this point on the recorder paper. Continue this procedure until every major dBm division on the meter has been calibrated on the recorder paper.

5. The actual level to the set as indicated on the recorder is equal to the algebraic sum of the RANGE setting and recorder indication.

Table 3-8. Transmission Loss Measurement

STEP PROCEDURE

1. For a transmission loss measurement to be meaningful, it should first be determined if there are any extraneous signals present that will affect your measurement. To do this, connect the measuring set to the circuit and determine if interfering signals are present. Levels below 60dB can, in most cases, be ignored. A butt-in can be connected to the AC MON jacks to aid in determining the interfering source.

2. Establish a connection like the ones shown in Figure 3-6.

3. Adjust the oscillator output level for 0dBm. Measure the level at the receiving end and record this level.

4. Insertion loss is equal to the difference between the sending level and the receiving level, ignoring any extraneous signals.

EXAMPLE:

Sending level = 0dBm Receiving level = (-)- 20dBm Insertion loss = 20dB

3-14

Model 3555B Section IV

SECTION IV

THEORY OF OPERATION

4-1. INTRODUCTION.

4-2. The Model 3555B Transmission and Noise Measuring Set is a special measuring set designed for uses in testing telecommunications equipment. Inputs between -90dBm and +30dBm full scale can be selected in twelve ranges for level measurements and correspond to the black markings on the meter scale and the RANGE switch. Noise measurements between 0dBrn and +120dBrn full scale can be made, selectable in twelve ranges and corresponds to the blue markings on the meter scale and RANGE switch. When measuring rapidly fluctuating noises, a damping circuit can be inserted by the RESPONSE switch. 4-3. Impedances of 75, 135 and 600 ohms, terminated or bridging can be selected for carrier level measurements. The 135 and 600 ohm functions can be either balanced or unbalanced while the 75 ohm function is unbalanced only. For voice frequencies, impedances of 600 and 900 ohms are provided. These impedances are selectable by the pushbutton FUNCTION switch and can be terminated or bridging, balanced or unbalanced. 4-4. A noise-to-ground (Ng) function is included to permit measurement of longitudinal noise. When the Ng pushbutton is depressed, a 40dB attenuator is placed across the INPUT terminals. 4-5. The HOLD function places a high inductance holding coil across the INPUT terminals to simulate an off-hook condition while measurements are being made. The HOLD function is not operative on any of the carrier functions. 4-6. A variety of INPUT and DIAL jacks are provided which accept Western Electric type 241 and 289 dual plugs, 309, 310, 347, and 358 single plugs, dual banana plugs, clip leads and bare wires.

4-7. BLOCK DIAGRAM DESCRIPTION.

4-8. Figure 4-1 illustrates a simplified block diagram

Set. Refer to this figure for the following block diagram description. 4-9. The input signal is first applied to the FUNCTION switch where the input circuitry is set up to accommodate the type of measurement being made. For voice frequencies, impedances of 900 ohms or 600 ohms can be selected, bridged or terminated. Voice frequencies are then applied to a transformer with a frequency range of 20Hz to 20kHz. The HOLD function places a high inductance bridge across the INPUT terminals to simulate an off-hook condition. For carrier frequencies impedances of 600 ohms, and 135 ohms can be selected, terminated or bridged, balanced or unbalanced. Carrier frequencies at these impedances are applied to a transformer having a frequency range from 5kHz to 600kHz. For 75 ohm carrier frequencies an unbalanced input is provided. This input can be either terminated or bridged. HOLD is not possible on any of the carrier functions. 4-10. For longitudinal measurements, an Ng function is provided which places a 40dB attenuator across the INPUT terminals. The HOLD function bridges the input with a holding coil while measurements are being made. The output of the 40dB attenuator is always applied to the voice frequency transformer. 4-11. The DIAL/BAT function serves two functions. First it connects the DIAL/AC MON jacks to the INPUT jacks so that a handset can be used for dialing. Secondly, the meter is connected to the unregulated power supply so that the battery condition can be monitored. 4-12.After the signal is conditioned by the input circuitry it is coupled to the RANGE attenuator where the signal level is adjusted to provide the proper input for the Input Amplifier. The RANGE attenuator provides from 0dB to 80dB of attenuation. It also provides gain switching for the Input Amplifier.

of the Model 3555B Transmission and Noise Measuring

Figure 4-1. Simplified Block Diagram

4-1

Section IV Model 3555B 4-13. The output of the Input Amplifier goes to the

INPUT switch where noise filters are set up for selection by the NOISE WTG switch. In the NOISE position, either 3kHz FLAT weighting, C Message weighting, 15kHz FLAT weighting or PROGRAM weighting can be selected by the NOISE WTG switch. In the TMS position of the INPUT switch the filters are bypassed for transmission level measurements. 4-14. The output from the INPUT switch goes to the meter amplifier. This amplifier provides an ac signal to the DIAL/AC MON jacks so that a handset can be used to listen to the signal being measured. This is particularly useful in determining noise characters. 4-15. The detector circuit provides an equivalent rms detected voltage to drive the meter. The meter has shaped pole pieces to provide a linear meter scale both for dBm and dBrn.

4-16. DETAILED CIRCUIT DESCRIPTION.

4-17. The purpose of the function switch is to set up the input conditions to match the type of measurement being made. Impedances can be selected to match the lines to be tested and can be either bridged or terminated. Separate transformers are selected for voice frequency and carrier frequency measurements. A 40dB attenuator is bridged across the input terminals for longitudinal noise measurements when the Ng pushbutton is depressed. The HOLD function places a high inductance holding coil across the input terminals to simulate an off-hook condition. Each of these functions is described in detail in the following paragraphs.

a. HOLD: When the HOLD pushbutton is

depressed a high inductance coil LI is connected across the Model 3555B balanced INPUT terminals if the INPUT

switch is in the TERM position. A bridging HOLD is not possible. The TERM switch connects the two windings of L1 in series.

b. DIAL BAT: (See Figure 4-2) The DIAL BA1

pushbutton serves two purposes. First it disconnects the meter from the detector and connects it to the unregulated power supply so that the battery voltage can be monitored. Secondly, the DIAL/AC MON jacks are disconnected from the amplifier ac output and connected to the INPUT jacks. This permits connecting the lineman's handset to the balanced line for the purpose of dialing.

c. Ng: (See Figure 4-3) The Ng pushbutton

connects a 40dB attenuator across the balanced input terminals for longitudinal measurements. This attenuator consists of A1R5 thru A1R8 and A1C1. The output is taken from the junction of AIC1 and A1R8. This output is referenced to ground and applied to the voice frequency transformer A1T2.

d. 900 (Vf/Nm): The 900 function switch S4

selects terminating resistors AIRI and A1R9 for 900 ohm terminations. The INPUT switch must be in _ the TERM position to complete the circuit for this termination. The 900 function switch also places a ground on the 900 ohm relay A3K1 which provides gain switching in the Input Amplifier so that the meter will indicate in dBm. The 900 ohm signal is applied to the voice frequency transformer A1T2. HOLD can be accomplished on this function.

Figure 4-2. Simplified DIAL BAT Function

4-2

Model 3555B Section IV

Figure 4-3. Simplified NG Function

e. 600 (Vf/Nm): The 600 function switch S5

selects terminating resistors A1R2 and A1R10 for a 600 ohm termination. The INPUT switch completes the circuit for this termination. The 600 (Vf/Nm) signal is applied to T2. No gain switching is performed in this function since the set is normalized at 600 ohms HOLD can be accomplished on this function.

f. 600 (Carrier): This function is identical to

the 600 (Vf/Nm) function except that the signal is applied to A1T1 and HOLD cannot be accomplished on this function.

g. 135 (Carrier): The 135 function is identical

to the 600 (carrier) function except that the gain switching in the Input Amplifier is accomplished by one section of the 135 function switch S7.

h. 75 UNBAL: The 75 UNBAL function

bypasses the balanced input circuitry and transformer AlT1 and A1T2. Gain switching is performed by one section of this function switch. When the 75 UNBAL function is selected the output of the balanced circuitry is disconnected. A 75 ohm termination is provided thru the INPUT switch.

4-18. RANGE ATTENUATOR A2.

4-19. The RANGE attenuator adjusts the input signal to a suitable level for the Input Amplifier. This

attenuator is composed of four L pads, selectable in combinations to provide from 0dB to 80dB of attenuation. Two 30dB pads are selected by A2S1A and A2S1B, a 20dB pad is selected by A2S1C and a 10dB pad is selected by A2S1D. Another section of the RANGE attenuator switch provides gain switching for the Input Amplifier in the -80dBm, -70dBm and -60dBm positions. Refer to Table 4-1 for more detailed information on range attenuation and amplifier gain.

4-20. INPUT AMPLIFIER A3. (Schematic No. 2)

4-21. The purpose of the Input Amplifier is to provide the necessary gain at each setting of the RANGE switch and to provide the necessary gain at all impedances. This amplifier is normalized at 600 ohms and the following discussion is for the 600 ohm function. 4-22. Diodes A3CR1 thru A3CR4 serve as protection for the input amplifier. Signals greater than 7 volts peak-to-peak will be conducted to ground through these diodes. The gain of this amplifier is determined by the negative feedback from the emitter of A3Q5 to the base of A3Q2. This feedback is first determined by the ratio of A3R13 to the sum of A3R14 and A3R15. In position 1 of the RANGE switch (-80DBM) this feedback is further divided by the ratio of A3R11 to the sum of A3R25 and A3R26. In position 2 (-70DBM) of the RANGE switch the feedback is determined by the ratio of A3R11 to the sum of A2R13, A3R25 and A3R26. In position 3 (-60DBM) of the switch the feedback is determined by the ratio of A3Rll to the sum of A2R13, A2R14, A3R25 and A3R26.

4-3

Section IV Model 3555B

Table 4-1. Range Attenuation and Amplifier Gain

RANGE RANGE ATTENUATOR

Setting Attenuation PADS USED Input Amplifier Gain

+30dBm 80dB 1,2,3 3.6dB +20dBm 70dB 1,2,4 3.6dB +10dBm 60dB 1,2 3.6dB

0dBm 50dB 2,3 3.6dB

-10dBm 40dB 2,4 3.6dB

-20dBm 30dB 2 3.6dB

-30dBm 20dB 3 3.6dB

-40dBm 10dB 4 3.6dB

-50dBm 0dB 0 3.6dB

-60dBm 0dB 0 13.6dB

-70dBm 0dB 0 23.6dB

-80dBm 0dB 0 33.6dB

In positions 4 thru 12 (-SODBM thru +30DBM), A3R11 is bypassed for maximum feedback. The gain of the amplifier in these nine positions is a constant 2.5dB. Potentiometer A3R26 is for calibration of the -80DBM range, 600 ohm function. Resistor A3R27 is used to maintain a charge on A3C22 to prevent transients when changing ranges. 4-23. In order that the meter always indicate in DBM regardless of the impedance selected, additional gain switching must be performed. When the 75 function is chosen, A3K2 energizes and places A3R16 in parallel with A3R14 and A3R15. This reduces the negative feedback (with respect to the 600 function) and increases the amplifier gain by 9dB. When the 135 function is selected, A3R22/R23/R24 are connected in series with A3R16. This combination is then in parallel with A3R14 and A3R15, reducing the feedback and increasing the amplifier gain by 6.4dB with respect to the 600 function. When the 900 function is depressed, A3R17, A3R19 and A3R20 are connected in parallel with A3R13, increasing the negative feedback and

reducing the amplifier gain by 1.7dB. Relays A3K1 thru A3K3 are controlled by the FUNCTION switch when any of the impedance functions except 600 are selected. 4-24. Transistors A3Q1 and A3Q2 form a differential amplifier. The signal is taken from the collector of A3Q1, amplified by A3Q4 and A3Q5 with A3Q5 providing feedback to the base of A3Q2. Transistor A3Q3 provides isolation between A3Q2 and A3Q4 to prevent undesired feedback. This results in a greater bandwidth than could be achieved without its use. The output signal is coupled through A3R17 and A3C10 to the INPUT switch.

4-25. FILTERS. (Schematic No. 3)

4-26. The 3555B contains a 3kHz FLAT weighting filter, a C MSG weighting filter, a PROG weighting filter and a 15kHz FLAT weighting filter. These active filters consist of five amplifiers with controlled feedback for waveshaping. They are used in combinations to form each of the filters (refer to Figure 7-1). Since all of these amplifiers are

Figure 4-4. Simplified Average Detection

4-4

Model 3555B Section IV

Figure 4-5. 3kHz FLAT and Program Weighting Curves

4-5

Section IV Model 3555B

Figure 4-6. C-MSG and 1SkHz FLAT Weighting Curves

4-6

Model 3555B Section IV identical in operation, only the first will be discussed in

detail. 4-27. Referring to Figure 7-4, the signal is applied to the assembly through pin 22. If C MSG is selected the signal is first attenuated by A4R1, A4R2 and A4R3A. Potentiometer A4R3A is for C MSG level adjustment for 0dB at 1kHz. The signal is then applied to the first in a series of amplifiers. The first amplifier consists of A4Q1 through A4Q4. Differential amplifier A4Q1 and A4Q2 amplifies the signal and applies it to A4Q3 and A4Q4. The emitter circuit of A4Q4 provides two feedback signals, positive feedback through A4R8 and A4C4 to the base of A4Q1 and negative feedback to the base of A4Q2. The gain of this amplifier is controlled by the ratio of the value of A4R10 to the value of A4R9. For example, increasing the value of A4R9 would increase the negative feedback and reduce the amplifier gain. Gain can be calculated by the equation:

A4R10

Gain = 1 + A4R9 Positive feedback to the base of A4Q1 determines the frequency response of this amplifier and is controlled by the value of A4C4 and A4R8. All five of the amplifiers are used in C Message weighting. 4-28. The Program weighting filter utilizes only amplifiers No. 2 and No. 3 as shown in Figure 7-1. These amplifiers are identical to the one described in the preceeding paragraph except for the value of the positive feedback utilized for shaping and the negative feedback used for gain control. This negative feedback is modified by resistance in the feedback divider at the base of A4Q12. Transistors A4Q5 and A4Q6 provide additional gain required for Program weighting. Potentiometer A4R3B is used for PROG level adjustment at 1kHz.

4-29. The 3kHz FLAT and 15kHz FLAT weighting filters utilize only amplifier as indicated in Figure 7-1. The only difference between these two active filters is in the positive feedback used for shaping and in the negative feedback used for gain. The negative feedback is altered by adding resistance to the feedback divider at the base of A4Q12.

4-30. METER AMPLIFIER. (Schematic No. 4)

4-31. The meter amplifier consists of A3Q6 through A3Q10. The signal is first amplified by differential amplifier A3Q6 and A3Q7. The signal is taken from the collector of A3Q6 and then amplified by A3Q9 and A3Q10. Transistor A3Q8 provides isolation between A3Q7 and A3Q9 to prevent undesired feedback. Two signals are taken from A3Q10. The collector circuit supplies a signal to the DIAL/AC MON jacks for the purpose of listening to the measured signal. The emitter circuit of A2Q10 provides a drive signal for the detector circuit.

4-32. DETECTOR. (Schematic No. 4)

4-33. The detector is a class B rms detector which combines the features of an average detector and a peak detector. When the average detected signals and the peak detected signals are combined in the proper proportion an equivalent rms response is produced. 4-34. First consider the average detection in this circuit. (See Figure 7-5). Transistors A3Q12-A3Q13 and A3Q15-A3Q16 are functionally symmetrical. This means that A3Q14 and A3Q17 are driven by the same signal. When the signal at the base of A3017 and A3Q14 goes negative, A3Q! 4 turns on and A3Q17 turns off. No current will flow through the meter. On the positive half cycle A3Q14 turns off and A3Q17 turns on. The current paths for the average detector are shown in Figure 4-4.

Figure 4-7. Simplified Peak Detection

4-7

Section IV Model 3555B

from either the battery or from an ac source, capacitor

4-35. Now consider the peak detection. (See Figure 7-5) When A3Q14 is turned on and A3Q17 is turned off, no current flows through the meter from the peak detector When A3Q14 is turned off and A3Q17 is turned on, the current path is as shown by the heavy lines in Figure 4-7 Diodes A3CR12 and A3CR13 are included to offset the junction drop of A3CR15 and A3CR16 respectively. 4-36. When the average detection and the peak detector are combined in the proper proportion, an equivalent rms response is produced. The advantage of this type of rms detection is fast response.

4-37. POWER SUPPLY AND SERIES REGULATOR (Schematic No. 4)

4-38. The 3555B can be operated from 115V or 230V ac, the internal 48V dry cell battery or from a central office battery (tip negative). When operating from an ac source power is applied through transformer TI and the AC/BAT switch S1 to the rectifier CR1. This rectified

voltage is filtered by C2 before being applied to the series regulator through J2, S3, CR1 and cable W1. 4-39. The regulator is of the conventional series type with A3Q19 acting as the sensing element and A3CR20 as the reference. Changes in the output level are amplified by differential amplifier A3Q18 and A3Q19. The output of the differential amplifier is amplified by A3Q20 and applied to A3Q21 which controls the conduction of the series transistor A3Q22. The output of this series regulator is held at - 20 volts ±1 volt. The maximum ac ripple and noise on the output voltage is 200µV rms. 4-40. It should be noted that when operating the set

C2 will always be charged whether the set is turned on or not. Caution should be exercised when servicing the power supply.

4-8

Model 3555B Section V

SECTION V

MAINTENANCE

5-1. INTROOUCTION.

5-2. This section of the manual contains information necessary in the maintenance of the -hp- Model 3555B Transmission and Noise Measuring Set. Included are performance checks, adjustment and calibration procedures and troubleshooting. 5-3. The test equipment needed to properly maintain and service the Model 3555B is listed in Table 5-1. Included in Table 5-1 is the equipment to be used, required specifications 'and recommended model. If the recommended model is not available other equipments

Table 5-1. Required Test Equipment

INSTRUMENT RECOMMENDED

TYPE REQUIRED CHARACTERISTICS MODEL

Oscillator Frequency Range: 20Hz to 3MHz -hp- 654A

Levels: -80dBm to +30dBm Accuracy: ±0.1 5dB

Oscillator Frequency Range: 100Hz to 20kHz -hp- 201 C

Amplitude: 30V Transformer Line matching -hp- 11004A Voltmeter, Function: AC and DC -hp- 3440A/3445A digital Accuracy: ±.1% Amplifier Voltage gain: 20 dB -hp- 467A Output: +/-20V peak at 0.5A peak Voltmeter, AC Frequency Range: 20Hz-4MHz -hp- 400FL

Accuracy: ±2% Termination 50 ohms ±.25% -hp- 11048B Termination 75 ohms ±.25% -hp- 11094A Cables Balanced BNC to 310 plug See Figure 5-1. Adapter BNC to 358 plug Trompeter Electronics

Resistors 576 ohms ±1% (1) -hp- Part No. 06984598

875 ohms ±1% (1) (Use 825 ohm, 0757-0731 and

300 ohms 0.1 % (4) -hp- Part No. 0698-6295

600 ohms ±0.1% (4) -hp- Part No. 0698-7408

135 ohms ±0.1%(4) -hp- Part No. 0698-7364

75 ohms ±0.1% (4) -hp- Part No. 0698-7363

900 ohms ±0.1% Use 600 and 300 in series (0.1%)

150 ohms ±.1% (2) -hp- Part No. 0698-6774

100 kilohms 1% (1) -hp- Part No. 0757-0465

can be substituted provided they meet the required specifications.

5-4. FACTORY SELECTED VALUES.

5-5. Factory selected values are denoted on the schematic diagrams by an asterisk. The nominal value is shown. The value in your instrument may be different or the part may be omitted.

5-6. 150 BAL CONVERSION.

a. To convert the 135 BAL function to a 150

BAL

No. AD-1W

49.9 ohm, 0698A4110 in series)

5-1

Section V Model 3555B

Figure 5-1. Balanced BNC to 310 Plug

function, remove or clip the shorting bar from across A1 R17 (see Figure 7-2).

b. Remove the 150 BAL decal from the small

envelope supplied with the set and stick it over the existing 135 BAL decal.

c. Adjust the 150 function as described in

Paragraph 5-20 in this manual.

5-7. PERFORMANCE CHECKS.

5-8. The performance checks presented in this section are in-cabinet checks designed to compare the Model 3555B with its published specifications. These checks can be used for incoming inspection, periodic maintenance checks and to verify performance after adjustment or repair. A performance check test card appears at the end of this section which can be used to record the specification performance of your set.

5-9. LEVEL ACCURACY CHECKS.

a. Connect only the 654A and 3555B as

shown in Figure 5-2 and set the 3555B controls as follows:

FUNCTION...........CARRIER, 75 UNBAL

INPUT .................................TMS, TERM

RANGE......................................+10dBm

b. Set the 654A frequency to 20kHz,

IMPEDANCE to 75 UNBAL and adjust the output level for +10dBm. If the calibration of the 654A is questionable, first connect the output of the 654A through a 75 ohm termination, directly to the input of the 3440A/3445A (3555B not connected) and measure the voltage. This level should be 866mV rms. If it is not, adjust the 654A amplitude control until it is and note the 654A meter indication for future reference. Now that the 654A calibration has been verified, disconnect

Figure 5-2. Level Accuracy Check

5-2

Model 3555B Section V

and change the 201C output level for

Table 5-2. 75 UNBAL Carrier Accuracy Check

3555B INDICATION (dBm)

RANGE

FREQUENCY

30Hz to 1MHz 100Hz to 600kHz 1MHz to 3MHz

+10dBm +10 ±0.5 +10 ±0.2 +10 ±0.5 ±10% of meter indication in dBm

0dBm 0 ±0.5 0 ±0.2 0 ±0.5 ±10% of meter indication in dBm

-10dBm -10 ±0.5 -10 ±0.2 -10 +0.5 ± 0% of meter indication in dBm

-20dBm -20 ±0.5 -20 ±0.2 -20 ±0.5 ±10% of meter indication in dBm

-30dBm -30 ±0.5 -30 ±0.2 -30 ±0.5 ±10% of meter indication in dBm

-40dBm -40 ±0.5 -40 ±0.2 40 ±0.5 ±10% of meter indication in dBm

-50dBm -50 ±0.5 -50 ±0.2 -50 ±0.5 ±10% of meter indication in dBm the 3440A/3445A and reconnect the output

of the 654A to the input of the 3555B. Maintain the 654A meter reference throughout the remainder of the following checks.

c. The 3555B meter should indicate 0dBm

±0.1 dBm.

d. Check all the RANGES and frequencies

listed in Table 5-2 for the specified tolerances. Be sure to maintain the 654A reference established in step b.

e. Change the 654A to 600 BAL and change

the 3555B to CARRIER, 600 BAL. Connect the 654A 600 BAL output to the 3555B input using a balanced cable.

f. Check the RANGES and frequencies in

Table 5-3, using the same procedure described for the 75 UNBAL function.

g. Change the 654A to 135 BAL and change

the 3555B to 135 BAL. Repeat step e for the same RANGES and tolerances indicated for the CARRIER 600 BAL function in Table 5.-3.

h. Change the 3555B to VF/Nm, 600 BAL and

change the 654A to 600 BAL. Check the +10dBm thru -80dBm ranges in Table 5-4 for the tolerances indicated.

i. Change the 3555B to 900 BAL and connect

a 150 ohm ± 1% resistor in series with each input lead. Readjust the 654A for 0dBM. Repeat the checks in Table 5-4 for the same tolerances.

j. To check the top two ranges, connect the

equipment as shown in Figure 5-3 and set the 3555B controls as follows:

FUNCTION....... VF/Nm 600 BAL

INPUT .................... TMS, TERM

RANGE..........................+20dBm

k. Adjust the 201C for 7.75V on the

3440A/3445A at 100Hz.

l. Tune the 201 C from 100Hz to 20kHz,

maintaining 7.75V on the 3440A/3445A. Between 100Hz and 15kHz, the 3555B indication must not change more than ±0.2dBm. Between 15 kHz and 20kHz, the indication must not change more than ±0.5dBm.

m. Check the +30dBm range using the

procedure described in Steps j through 1, except change the 3555B range to +30dBm

24.49V.

n. To check the 900 ohm function on the

+20dBm and +30dBm ranges, connect a 300 ohm +0.1% resistor in series with the 3555B input in Figure 5-3.

o. Change the 3555B to 900 BAL and change

the range to +20dBm.

p. Adjust the 201 C output for 9.49V as

indicated on the 3440A/3445A.

q. Check for the tolerances indicated in Table

5-4 for the +20dBm range.

r. Change the 3555B range switch to +30dBm

and adjust the 201C for 30V on the 3440A/3445A. Check for the tolerances indicated in Table 5-4 for the +30dBm range.

Table 5-3. Carrier Level Accuracy

3555B Indication (dBm)

RANGE 135 1kHz -600kHz 10kHz - 300kHz

600 1kHz - 150kHz 10kHz - 100kHz

-50 thru +10dBm ±0.5 ±0.2* *Increase specification by ±0.3dB on 135 ohms (or 150

ohms) when not battery powered.

5-3

Section V Model 3555B

Figure 5-3. +20dBm and +30dBm Level Accuracy Check

5-10. RETURN LOSS CHECK.

a. To make a return loss check it will first be

necessary to construct a balanced bridge utilizing 0.1% resistors for each of the four 3555B impedances. Figure 5-4 shows the equipment test set-up to be used. For this check to be meaningful, all test leads should be kept short. The leads connecting the 3555B to the bridge should be short clip leads and should be kept away from each other and from other leads. Keep all the instruments away from other instruments that may be referenced to earth ground.

b. Connect the equipment as shown in Figure

5-4 and set the 3555B controls as follows:

Table 5-4. VF/Nm Level Accuracy Checks 600 BAL and 900 BAL

RANGE 20Hz to 20kHz 40Hz to 15kHz 100Hz to 20kHz 100Hz to 15kHz

+30dBm +30 ±0.5 +30 ±0.2 +20dBm +20 ±0.5 +20 ±0.2 +10dBm +10 ±0.5 +10 ±0.2

0dBm 0 ±0.5 0 ±0.2

-10dBm -10 ±0.5 -10 ±0.2

-20dBm -20 ±0.5 -20 ±0.2

-30dBm -30 ±0.5 -30 ±0.2

-40dBm -40 ±0.5 40 ±0.2

-50dBm -50 ±0.5 -50 ±0.2

-60dBm -60 ±0.5 -60 ±0.2

-70dBm -70 ±0.5

-80dBm -80 ±0.5

FUNCTION..................VF/Nm, 600 BAL

INPUT................................TMS, TERM

RANGE........................................0dBm

NOTE The 3555B does not have to be turned on for this check. If at any frequency the 3555B return loss check is out of specification, check the reference at that frequency as described in the following procedure.

c. Set the 654A frequency to 1kHz.

Temporarily close S1 in Figure 5-4 and adjust the 654A output level for an up scale indication on the 400FL AC Voltmeter.

-80dBm through +30dBm

5-4

Model 3555B Section IV

Figure 5-4. Return Loss Test Set-Up

d. Open S1 and down range the 400FL for an

on-scale indication. This indication subtracted from the reference established in step c, is the bridge balance and should be greater than the return loss specification.

e. Unplug or disconnect R4 in Figure 5-4 and

connect the 3555B tip and ring in its place. Be sure to use short clip leads.

f. Momentarily close S1 and recheck the

reference on the 400FL. .Open S1 in Figure 5-4 and down range the 400FL for an on-scale indication. This indication must be down at least 30dB from the reference.

g. Tune the 654A from 50Hz to 20kHz. The

400FL indication must remain at least 30dB down from the reference.

h. Change the 3555B FUNCTION to

CARRIER 600 BAL and repeat steps f and g between 3kHz and 150kHz. Return loss must be at least 26dB down from the reference.

i. Change the bridge resistors in Figure 5-4 to

900 ohms f 0.1% (use 300 ohms + 0.1% in series with 600 ohms ±0.1%) and change the 3555B FUNCTION to VF/Nm 900 BAL. Be sure to reset the reference level after the resistors are changed. Check the return loss between 50 Hz and 20 kHz. The return loss must be better than 30 dB.

FIG 5-1

Figure 5-5. Filter Response Test Set-UP

5-5

Section V Model 3555B

the 654A for

Figure 5-6. Bridging Loss Test Set-Up

j. Change the bridge resistors in Figure 5-4 to

135 ohms +0.1% and change the 3555B FUNCTION to 135 BAL. Check the return loss between 1kHz and 600kHz. The return loss must be better than 26dB down from the reference.

k. Change the 3555B input connection to the

75 UNBAL jack. Change the resistors in Figure 5-4 to 75 ohms +0.1% and change the 3555B FUNCTION to CARRIER 75 UNBAL.

l. Check the return loss between 1kHz and

3MHz. The return loss must be better than 30dB down from the reference.

5-11. FILTER RESPONSE CHECKS.

a. C MSG FILTER RESPONSE

Table 5-5. Filter Response Checks

FREQUENCY C MSG (dBm) 3kHz FLAT (dBm) 15kHz FLAT (dBm) PROGRAM (dBm)

60Hz -55.7 ±2 0 ±1.75 0 ±1.75 200Hz -25 ±2 -17.3 ±2 250Hz 0 ±1 0 ±1 500Hz -7.5 ±1 -6.6 ±1

1kHz 0(Ref) 0(Ref) 0(Ref) 0(Ref)

2kHz -1.3 ±1 -0.5 ±1.75 4.8 ±2

2.5kHz -1.4 ±1 -1.5 ±2 3kHz -3 ±3 +6.5 ±2 4kHz -14.5 ±3 +6.5 ±2 5kHz -28.5 ±3 0 ±1 +6.5 ±2 6kHz +6.4 ±3 8kHz +4 ±3

10kHz -0.5 ±1.75 -8.5 ±4

12.5kHz -1.5 ±2 15kHz -3 ±3

1. Connect the equipment as shown in Figure 5-5 with S1 in position 1 and set the 3555B controls as follows:

FUNCTION......... VF/Nm 600

INPUT ............NOISE BRDG

RANGE .......................0dBm

2. Adjust the output of 0dBm at a frequency of 1 kHz.

3. Check the frequencies listed in Table 5-5 for the tolerances indicated.

b. 3kHz FLAT FILTER RESPONSE

1. Set the 654A frequency to 1kHz and adjust the output level for 0dBm.

2. Check the frequencies listed in Table 5-5 for the tolerances indicated.

c. 15kHz FLAT FILTER RESPONSE

5-6

Model 3555B Section V

1. Reset the 654A output level for 0dBm indication on the 3555B meter at a frequency of 1kHz.

2. Check the frequencies listed in Table 5-5 for the tolerances indicated.

d. PROG FILTER RESPONSE

1. Reset the 654A frequency to 1kHz and adjust the output level for 0dBm indication on the 3555B meter.

2. Check the frequencies listed in Table 5-5 for the tolerances indicated.

5-12. BRIDGING LOSS.

a. Connect the equipment as shown in Figure

5-6 and set the 3555B controls as follows:

FUNCTION............VF/Nm 600

INPUT...................TMS BRDG

RANGE.......................... 0dBm

b. Adjust the output of the 654A (600 ohm

function) for 0dBm indication on the 400FL at a frequency of 1kHz.

c. Connect the 3555B to the 400FL input.

The indication on the 400FL should not drop more than 0.3dB.

d. Change the FUNCTION switch to

CARRIER 600 and repeat the above procedure at a frequency of 10kHz. The 400FL indication should not drop by more than 0.05dB.

e. Change the equipment setup by connecting

a 300 ohm ±1% resistor in series with the 400FL input and change the resistor connected across the 400FL input to 900 ohms ±1%.

f. With the 400FL set to the 0dB range, adjust

the 654A output level for exactly 0dB indication on the 400FL.

g. Change the 3555B FUNCTION to VF/Nm

900 and connect the 3555B input to the 400FL input terminals. The 400FL indication must not drop by more than

0.3dB.

5-13. INPUT BALANCE.

a. Set the 3555B controls as follows:

FUNCTION............VF/Nm 600

INPUT...................TMS BRDG

RANGE.......................... 0dBm

b. Connect the 654A 600 ohm output to-the

tip and ring input of the 3555B. Set the output frequency of the 654A to 60Hz and adjust the amplitude control for 0dBm indication on the 3555B meter.

c. Change the equipment setup to that shown

in Figure 5-7.

d. Change the 3555B RANGE switch to

-80dBm. The 3555B indication (meter + RANGE setting) must be down at least 80dB.

e. Change the 3555B RANGE switch to

-70dBm and tune the 654A to 6kHz. The 3555B indication must be down at least 70dB.

f. Change 3555B RANGE to -60dBm and

tune the 654A to 20kHz. The 3555B indication must be down at least 50dB.

g. Change the 3555B FUNCTION switch to

Figure 5-7. Input Balance Test Set-Up

5-7

Section V Model 3555B

Check the frequencies listed in Table 5-2 for

CARRIER 600 and repeat the above procedure. Between 1kHz and 10kHz, the balance must be greater than 70dB. Between 10kHz and 100kHz, the balance must be better than 60dB. Between 100kHz and 600kHz, balance must be better than 40dB.

5-14. ADJUSTMENT AND CALIBRATION PROCEDURE.

5-15. The following is a complete adjustment and calibration procedure for the Model 3555B. These adjustments should be performed only after it has been determined by the performance checks that the set is not operating within its published specifications.

5-16. POWER SUPPLY CHECK.

5-17. Before attempting the following calibration procedures, first check the power supply voltage to be sure that it is correct and that the ripple voltage is not abnormal. To do this perform the following steps.

NOTE Calibration of the 3555B should be performed with the set operating from the internal battery except for the power supply ripple check in the following steps. Operate the set from the ac power source long enough to make this check and then return the set to internal battery operation. This is accomplished by changing the position of the slide switch mounted on the side of the set. When operating from the battery, disconnect the ac power cord from the set.

a. Remove the set from the case and connect

the 3440A/3445A dc voltmeter between the 20V supply and ground. The negative side of A3C34 is a convenient place.

b. Turn the set on. The 3440A/3445A should

indicate -20 volts ±1.0V.

c. Connect the 400FL AC Voltmeter to the

negative side of A3C34 and measure the ripple voltage. The maximum allowable ripple is 200uV rms.

5-18. 75 UNBAL CALIBRATION.

a. Connect the 654A and 3440A/3445A as

shown in Figure 5-2 and set the 3555B controls as follows:

FUNCTION................ 75 UNBAL

INPUT..................... TMS, TERM

RANGE..........................+10dBm

b. Set the 654A frequency to 10 kHz, 75

UNBAL, and adjust the output level for 866 mV (+ 10 dBm) indication on the 3440A/3445A.

c. Set the 654A meter for a reference indication

and be sure to maintain this indication throughout the following procedures unless otherwise instructed. Disconnect the 3440A/3445A voltmeter.

d. Change the 654A to -50dBm and change the

3555B RANGE switch to -50dBm.

e. Disconnect the 3440A/3445A, the 11094A

termination and the cable. Connect the 654A output directly to the 3555B input.

f. Adjust A3R43 for 0dBm indication on the

3555B meter.

g. Change 654A frequency to 3MHz

maintaining the reference established on the 654A meter.

h. Adjust A3C8 for 0dBm indication on the

3555B meter.

5-19. ATTENUATOR CALIBRATION.

a. Remove the FUNCTION board and replace it

with the test board supplied with the set.

b. With the equipment and controls set as in

the preceding check, change the 3555B RANGE to 40dBm and change the 654A attenuator to -40dBm. Change the 654A frequency to 100kHz.

c. Adjust A2C12 for 0dBm indication on the

3555B meter.

d. Change the 3555B RANGE switch to

-30dBm and change the 654A attenuator to 30dBm. Adjust A2C7 for 0dBm indication on the 3555B meter.

e. Change the 3555B RANGE switch to

-20dBm and change the 654A attenuator to 20dBm. Adjust A2C4 for 0dBm indication on the 3555B meter.

f. Change the 3555B RANGE switch to

+10dBm and change the 654A attenuator to +10dBm. Adjust A2C1 for 0dBm indication on the 3555B meter.

the tolerance indicated. If any of the checks in Table 5-2 do not meet the indicated tolerances, repeat steps b through f.

5-20. FUNCTION CALIBRATION.

a. Remove the test board from the set and

install the function board assembly. Connect the 654A balanced output to the 3555B balanced input terminals. See Figure 5-5. Set the 3555B controls as follows:

FUNCTION........ CARRIER, 600 BAL

INPUT ...........................TMS, TERM

RANGE ................................ -50dBm

b. Set the 654A frequency to 10kHz and adjust

the output attenuators for -5OdBm output level, using the 600 BAL output function.

5-8

Model 3555B Section V

adjust the output level of the 654A for

it will be necessary to change the value of

c. Adjust A3R15 for 0dBm indication on the

3555B meter.

d. Change the 654A frequency to 1kHz.

Change the 3555B FUNCTION switch to VF/Nm, 600 BAL. Compare the 3555B meter indication with the indication in step c. If any difference exists, adjust A3R15 to split the difference between these two indications.

NOTE If the set is being operated from the ac line ground currents may be encountered on the low ranges, particularly if other instruments are connected in any way to the 3555B. In order to eliminate this problem, operate the set from its own internal battery or use the C MSG filter. If the C MSG filter is used, perform the filter calibration described in Paragraph 5-24 and then perform the following step.

e. Change the 654A to -80dBm output .level

at 1.00kHz. Change the 3555B RANGE switch to -80dBm. Adjust A3R26 for 0dBm indication on the 3555B meter.

f. Change the 654A to 135 BAL (150 BAL)

and change the 3555B FUNCTION to 135 BAL (I50 BAL). Adjust A3R24 for 0dBm indication on the 3555B meter.

g. Change the 3555B RANGE switch to -

5OdBm, INPUT switch to TMS TERM, and the FUNCTION switch to VF/Nm 600 BAL. Change the 654A to 1kHz at an output level of -50dBm, 600 BAL. Adjust the AMPLITUDE control for exactly 0dBm indication on the 3555B meter.

h. Change the 3555B FUNCTION switch to

900 BAL without changing anything else. Adjust A3R20 for -0.15dBm indication on the 3555B meter.

5-21. FREQUENCY RESPONSE ADJUSTMENT.

a. The following adjustment consists of

selecting fixed values for frequency compensation at 20Hz, 600 BAL, -70dBm and 20kHz, 600 BAL, -70dBm.

b. Connect the 654A 600 BAL output to the

3555B input. Set the 3555B controls as follows:

RESPONSE............................. DAMP

c. Set the 654A (600 BAL) output level to

0dBm at a frequency of 20Hz. The 3555B meter should Section V indicate -0.1SdBm +0.3dBm. Note this indication.

d. Change the 654A output level to -70dBm at

a frequency of 20Hz. Change the 3555B RANGE switch to -70dBm and change the FUNCTION to VF/Nm 600 BAL. The 3555B meter should indicate 0dBm +0.3dBm. Note the exact indication.

e. Compensation should be made between

the 900 BAL, 0dBm check (step c) and the 600 BAL, -70dBm check (step d). To raise the level, increase the value of A3R72 until the 900 BAL 0dBm check indicates high by the same amount that the 600 BAL, 70dBm check indicates low. The total difference should not exceed +0.3dBm.

5-22. COMMON MODE ADJUSTMENT.

a. Connect the equipment as shown in Figure

5-5 and set the 3555B controls as follows:

FUNCTION................VF/Nm, 600 BAL

INPUT...............................TMS, TERM

RANGE.......................................0dBm

b. Set the 654A frequency to 20kHz and

0dBm indication on the 3555B meter.

c. Disconnect the left output terminal on the

654A and short the tip and ring together on the cable. Down range the 3555B RANGE switch for an on-scale indication.

d. Adjust A1C7 for minimum indication on the

3555B meter. This indication must be down at least 60 dB.

e. Change the 3555B FUNCTION switch to

CARRIER, 600 BAL and change the 654A frequency to 100kHz.

f. Use the procedure described above and

adjust A1C4 for minimum indication on the 3555B meter. This indication must be down at least 40dB.

5-23. BALANCE CHECK.

a. First check the balance as described in

paragraph 5-13 to be sure that the balance does not meet specifications. If it does, disregard this step. If it does not perform the following procedure.

b. Since there are no adjustments for balance

FUNCTION............... VF/Nm 900 BAL

INPUT.............................TMS, TERM

RANGE..................................... 0dBm

a fixed factory selected capacitor. To adjust the balance on the

5-9

Section V Model 3555B

To gain access to the RANGE attenuator

To reassembly the set, use the reverse of

tree, refer to the paragraph indicated for

CARRIER function, change C4. To change the balance on VF/Nm, change the value of A1C9.

c. To determine whether the value of these

capacitors should be increased or decreased, lightly touch the tip and ring banana jack insulators and watch the direction in which the meter indication goes. The side (tip or ring) that causes the meter indication to decrease needs added capacitance. The capacitance should be changed in very small steps and checked again.

5-24. FILTER CALIBRATION.

a. Connect the equipment as shown in Figure

5-5 with S1 in position 1 and set the 3555B controls as follows:

FUNCTION................VF/Nm, 600 BAL

RANGE.......................................0dBm

INPUT...........................NOISE, TERM

NOISE WTG.......................3kHz FLAT

b. Connect a frequency counter to the 3555B

AC MON terminals and adjust the 654A frequency to exactly 1.00kHz as indicated on the frequency counter. Adjust the 654A output level for exactly 0dBm.

c. Adjust A4R3C for 0dBm indication on the

3555B meter.

d. Change the NOISE WTG switch to 15kHz

FLAT and note the meter indication. If it differs from the indication set up in step c, adjust A4R3C to split the difference between these two indications.

e. Change the 3555B NOISE WTG switch to

C MSG and adjust A4R3A for 0dBm indication on the 3555B meter.

f. Change the 654A frequency to 3.00kHz

and adjust A4R3D for an indication of -

2.15dBm on the 3555B meter.

g. Repeat steps e and f until both points are

within specifications.

h. Change the 3555B NOISE WTG switch to

PROG and change the 654A frequency back to 1.001Hz with the output level still set to 0dBm. Adjust A4R3B for 0dBm indication on the 3555B meter.

5-25. ASSEMBLY REMOVAL.

5-26. To gain access to the various assemblies in the 3555B use the following procedure.

a. Turn the set off and. remove it from the

case by removing four front panel screws.

b. Unplug the small cable on the A3

assembly.

c. Remove the two screws that secure the A3

board.

d. Gently lift up the bottom of the A3 board to

unplug it from the A1 FUNCTION assembly.

e. Hold the bottom of the A3 board high

enough to clear the FUNCTION board and pull the A3 assembly out. This is easily accomplished by gently rocking the board back and forth while pulling it down (toward the FUNCTION board).

f. Once the A3 assembly has been removed,

the AI FUNCTION board can be removed by pulling it out.

(A2), Input switch and the NOISE WTG switch, the shield must be removed. To do this, remove the two screws on each side of the set and lift out the shield.

the procedure described above.

5-27. TROUBLESHOOTING PROCEDURES.

5-28. The following information is supplied to assist in locating a malfunction in the set in a minimum of time. It should first be determined that a malfunction does indeed exist and that the trouble is not external to the set. 5-29. Before starting to troubleshoot the set, use the front panel controls to determine exactly which function, if any, is operating properly. Table 5-6 can aid you in this analysis. In many cases a good front panel analysis of the symptoms can lead you directly to the trouble. 5-30. To simplify troubleshooting the following information is supplied:

a. Troubleshooting Tree - - The

troubleshooting tree (Figure 5-8) is based on the half-split method of troubleshooting a set. The trouble can be isolated to a general area or block using this tree. Once the trouble has been isolated to an area, a reference is given. to a paragraph where more specific information can be found.

b. Functional Block Diagram - - The functional

block diagram can also be used to isolate the trouble to block. The diagram contains all of the essential blocks that make up the set and includes voltage levels, test points and adjustments. The troubleshooting tree and functional block diagram are keyed together by the numbers with a circle around them. If the levels or indications in your set do not agree with those on the functional block diagram or troubleshooting

more detailed information.

5-10

Model 3555B Section V

5-11

Paragraph 5-38

Paragraph 5-37

Paragraph 5-36

Paragraph 5-35

Figure 5-8. Troubleshooting Tree

Section V Model 3555B

Table 5-6. Front Panel Trouble Analysis

INPUT CONDITIONS FUNCTION (RANGE + METER)* INDICATES ACTION

FUNCTION: VF/Nm DIAL BAT In green area, BAT GOOD Replace battery

1kHz, 0dBm, 600 BAL Input: TMS, TERM

VF/Nm: 600 BAL 0dBm ±0.2dBm Refer to Paragraph 5-34 Change INPUT to BRDG

RANGE to +10dBm +6dBm ±0.2dBm Refer to Paragraph 5-34 Depress 900 BAL +4.2dBm ±0.2dBm Refer to Paragraph 5-34 INPUT to TERM

RANGE to 0dBm -0.1 5dBm ±0.2dBm Refer to Paragraph 5-34

FILTERS INPUT: NOISE TERM 0dBm Refer to Paragraph 5-37

NOISE WTG: 3kHz FLAT VF/Nm, 600 BAL 0dBm ±0.2dBm Refer to Paragraph 5-37

Change to C MSG 0dBm +±0.2dBm Refer to Paragraph 5-37 Change to 15kHz FLAT 0dBrn ±0.2dBm Refer to Paragraph 5-37 Change to PROG 0dBm ±1dBm Refer to Paragraph 5-37

FUNCTION: CARRIER

20kHz, 0dBm INPUT: TMS, TERM 600 BAL FUNCTION: CARRIER 0dBm Refer to Paragraph 5-34

600 BAL

Change INPUT to BRDG RANGE to +10dBm +6dBm ±0.5dBm Refer to Paragraph 5-34

3555B SHOULD INDICATE SET ACTUALLY CORRECTIVE

Depress 135 BAL RANGE to +20dBm +12.6dBm ±0.5dBm Refer to Paragraph 5-34

Change INPUT to TERM RANGE to 0dBm -2.2dBm ±0.5dBm Refer to Paragraph 5-34

Change to 75 UNBAL INPUT: TMS, TERM

RANGE

1kHz, 600 BAL, LEVEL +10dBm Change RANGE to +10dBm

LEVEL -10dBm Change RANGE to -10dBm -10dBm ±0.2dBm See Paragraph 5-35 LEVEL -20dBm Change RANGE to -20dBm -20dBm ±0.2dBm See Paragraph 5-35

FUNCTION: 75 UNBAL 0dBm ±0.2dBm Refer to Paragraph 5-34 RANGE: 0dBm

Change INPUT to BRDG RANGE to 10dBm ±6dBm +0.2dBm Refer to Table 5-8

Change INPUT back to

TERM

RANGE to 0dBm 0dBm ±0.2dBm Refer to Table 5-8

FUNCTION: VF/Nm 600 BAL +10dBm ±0.2dBm See Paragraph 5-35

5-12

Model 3555B Section V

function is defective. Refer to Table 5-7 for

Table 5-6. Front Panel Trouble Analysis (Cont'd)

INPUT CONDITIONS FUNCTION (RANGE + METER)* INDICATES ACTION

LEVEL -30dBm Change RANGE to -30dBm -30dBm ±0.2dBm See Paragraph 5-35 LEVEL 40dBm Change RANGE to 400dBm -40dBm ±0.2dBm See Paragraph 5-35, LEVEL -500dBm Change RANGE to -50dBm -50dBm ±0.2dBm See Paragraph 5-35, LEVEL -60dBm Change RANGE to -60dBm -60dBm ±0.2dBm See Paragraph 5-35, LEVEL -70dBm Change RANGE to -70dBm -70dBm ±0.2dBm See Paragraph 5-35, LEVEL -80dBm Change RANGE to -80dBm -80dBm ±0.2dBm See Paragraph 5-35, LEVEL 0dBm RANGE to 0dBm 0dBm

INPUT: TMS, TERM Measure 270mV ac

NG CHECK 75 UNBAL, Connect RANGE: 0dBm Adjust oscillator

UNBAL signal FUNCTION: VF/Nm level for 0dBm between tip and ring 600 BAL on 3555B meter

Change input Depress NG button -40dBm Refer to Table 5-8

connection. Connect Change RANGE to 40dBm signal between tip and ring and sleeve *Some meter jitter may (tip and ring shorted be experienced, but the together), ground reading should be within lead to sleeve the tolerance indicated.

3555B SHOULD INDICATE SET ACTUALLY CORRECTIVE

Table 5-9 Table 5-9 Table 5-9 Table 5-9 Table 5-9

±0.2dBm at AC MON jacks See Paragraph 5-38

c. Schematics-- The schematic diagrams

contain dc voltage levels and signal levels for a specified input condition. This will assist in troubleshooting individual circuits.

5-31. FRONT PANEL TROUBLESHOOTING.

5-32. Before attempting to troubleshoot the set, first determine from the front panel controls exactly which functions are performing properly and which ones are not. In this way, many troubles can be isolated to a specific area and sometimes to a component. 5-33. Table 5-6 is a step by step procedure for checking out the front panel controls. This table indicates what the results should be for each check along with the specified tolerance. A space is provided to enter your results. If these spaces are completed for each check, they will be of great assistance in making further troubleshooting checks. Whenever a discrepancy exists between your results and those

indicated in column 3, refer to the "corrective action" column.

NOTE This table is designed to help locate catastrophic failures. If your set is only out of the specified tolerances, a complete adjustment and calibration procedure should be performed as described in Paragraph 5-14.

5-34. FUNCTION TROUBLESHOOTING.

a. First determine from the Front Panel

Analysis chart (Table 5-6) exactly which the probable cause of the malfunction in

the FUNCTION switch assembly.

5-35. RANGE TROUBLESHOOTING.

5-13

Section V Model 3555B

energizing ground supplied through either

Check the voltage at the junction of

attempt should be made to change the filter

characteristics. Return the filter to your

the signal at the input of the meter

malfunction is ahead of the meter amplifier

Table 5-7. Function Troubleshooting

DEFECTIVE

FUNCTION VF/Nm CARRIER

75 UNBAL A3K2 135 BAL A1T2, A3K3,

A3R22,A3R23,

A3L1, A3R24 600 BAL A1T2 600 BAL A1T1 900 BAL A1T1, A3K1,

A3R19, A3R20

NG A1R5 thru

A1R8, A1C1, A1S3

HOLD L1A/B, A1S1

DIAL BAT A1S2, A3R59

a. First determine from the Front Panel

Trouble Analysis chart (Table 5-9) exactly which range or ranges are defective.

b. Refer to Table 5-9 to determine the

changes that take place when switching ranges. Select the attenuator pads and/or gain switching resistors that match your symptom and check them.

5-36. TROUBLESHOOTING THE INPUT AMPLIFIER.

a. Check the dc voltages as indicated in

Figure 7-3 to determine if a catastrophic failure does exist. If the dc voltages are abnormal (greater than + 10% of the indicated level), check for open or shorted components in the area of the abnormal indication.

b. Check to see that A3K1, A3K2 and A3K3

are operating properly. All relays are deenergized when either of the 600 BAL FUNCTION pushbuttons is depressed. Depress each of the other impedance functions (900 BAL, 135 BAL and 75 UNBAL) to see that A3K1, A3K3 and A3K2 respectively, energize and de-energize properly. If any relay fails to operate

properly, check the relay and the pins 1, 2 or 3 on XA1.

5-37. FILTER TROUBLESHOOTING.

a. First determine that the set is operating in

the TMS input mode. This bypasses the filters. If the set functions properly in the TMS mode, check each of the filters by applying a 1kHz signal at a 0dBm level to the set. All filters are calibrated for 0dBm indication on the 3555B meter at a frequency of 1kHz.

b. Since all the amplifiers in Figure 7-1 are

used in C MSG, the loss of any one will obviously cause the loss of the C MSG weighting. However, the bad amplifier can be isolated by checking the other filters. Use the following guide to isolate the trouble to a particular amplifier.

1. First be sure that the filters have the correct operating potential applied.

A4R49 and A4C33 to be sure that there is -20 volts + 1 volt.

2. If none of the filters work, check A3 in Figure 7-1 (A4Q 11 through A4Q14).

3. If the PROG filter does not work but the others do, check A6 (A4Q5 and A4Q6).

4. If C MSG does not work but the others do, check A1, A4 and A5.

c. After the trouble has been isolated to an

amplifier, check the dc potentials indicated on the schematic diagram. This will normally isolate the trouble to a component. If the dc levels are correct but the filter response is out of tolerance, no

nearest -hp- Sales and Service office listed in the back of this manual.

5-38. TROUBLESHOOTING THE METER AMPLIFIER AND DETECTOR.

a. Inject a 1kHz, 0dBm signal (.775V rms) into

the 3555B and set the INPUT switch to TMS TERM, RANGE to 0dBm and the FUNCTION to VF/Nm, 600 BAL. Measure

amplifier (XA3 pin 9). The signal level should be 6.2mV rms. If not the

(refer to troubleshooting tree, Figure 5-8).

5-14

Model 3555B Section V

Table 5-8. FUNCTION Switch Resistance Values

NOTE The following resistance measurements were made with C1 shorted. Be sure to remove the short after completion of your measurements.

INPUT JACKS DIAL/AC MON JACKS

FUNCTION Tip to Ring Tip to Ground Ring to Ground

BRDG TERM BRDG TERM BRDG TERM

DIAL BAT NG 80.4 kilohms 80.4 kilohms NG HOLD 80.4 kilohms 700 ohms VF/Nm 900 BAL 900 ohms

DIAL JACKS, resistance is

900 BAL HOLD 400 ohms infinite Tip to Ring, Tip to

Ground and Ring to

600 BAL 600 ohms Ground on all functions. 600 BAL HOLD 350 ohms CARRIER 600 BAL 600 ohms 600 BAL HOLD 600 ohms 135 BAL 135 ohms 135 BAL HOLD 135 ohms 75 UNBAL, to Ground BRDG: 100 kilohms, -30dBm thru +30dBm ranges

120 kilohms, 40dBm Range 400 kilohms, -50dBm thru -80dBm ranges

TERM: 75 ohms

b. With a 6.2mV rms signal at XA3 pin 9,

measure the signal at XA1, pin 6 or at the AC MON jacks. This signal should be 270mV rms ± l10o. If not, check A3Q6 through A3Q10 and associated components, using the dc levels indicated in Figure 7-5.

5-39. FACTORY SELECTED VALUES.

5-40. Table 5-11 lists all the factory selected components in the Model 3555B, along with the purpose of each. Nominal values are shown on the schematic diagrams in Section VII and in the parts list, Table 6-1.

c. If a 270mV rms signal appears at the AC

MON jacks, check the detector circuit (A3Q11 through A3Q17).

5-15

Section V Model 3555B

Table 5-9. Range Attenuation and Amplifier Gain

Attenuator Pads Used Amplifier Gain

(See Figure 7-3) Switching

RANGES 1 2 3 4

+30 X X X +20 X X X +10 X X

0 X X

-10 X X

-20 X

-30 X

-40 X

-50

-60 A2R13, A2R14

-70 A2R13

-80

Ranges Affected +30 -20 +30 +20 -60 and -70 If Defective +20 thru 0 -10

+10 +30 -30 -40

Table 5-11. Factory Selected Values

Designator Purpose

C4 Adjust balance at 600kHz, 135 BAL A1C5 Padding capacitor for A1 C4

A1C9 Adjust balance 20kHz, 600 BAL (VF/Nm) A1C8 Padding capacitor for A1C7 A1C10 and Frequency response correction for A1TI

A1R12

A1R14 600 BAL, VF/Nm calibration A3C1 Padding capacitor for A2C12 A3C15 Frequency response, 20Hz, -80dBm, 600

BAL (VF/Nm)

A3R46 Adjust the bias level for A3Q10 (-10V at +

side of A3C24)

A3R72 Response, 20Hz, 600 BAL (VF/Nm)

-70dBm and 20Hz, 900 BAL, 0dBm. Compromise between these two settings.

A3R74and Meter tracking at 1/3 full scale. Resistors

A3R75 should be the same value.

Table 5-10. Resistance Checks

RANGE (dBm) Pin 1 to 3 Pin 2 to 3 Pin 1 to 2

-50 thru +30 154 kilohms 0 Infinity

-60 13 kilohms 28.64 kilohms 41.6 kilohms

-70 2.33 kilohms 28.64 kilohms 31 kilohms

-80 0 28.64 kilohms 28.64 kilohms

5-16

PERFORMANCE CHECK TEST CARD

Hewlett-Packard Model 3555B Tests Performed By Transmission and Noise Measuring Set Serial No. Date

DESCRIPTION CHECK

CARRIER 75 UNBAL

LEVEL ACCURACY CHECK

30Hz to 1MHz

+10dBm Range +10dBm ±0.5dBm

0dBm Range 0dBm ±0.5dBm

-10dBm Range -10dBm ±0.5dBm

-20dBm Range -20dBm ±0.5dBm

-30dBm Range -30dBm ±0.5dBm

-40dBm Range -40dBm ±0.5dBm

-50dBm Range -50dBm ±0.5dBm

100Hz to 600kHz

+10dBm Range +10dBm ±0.2dBm

0dBm Range 0dBm ±0.2dBm

-10dBm Range -10dBm ±0.2dBm

-20dBm Range -20dBm ±0.2dBm

-30dBm Range -30dBm ±0.2dBm

-40dBm Range -40dBm ±0.2dBm

-50dBm Range -50dBm ±0.2dBm

1MHz to 3MHz

+10dBm Range +10dBm ±0.5dBm ±10% of meter indication

-10dBm Range -10dBm ±0.5dBm ±10% of meter indication

-20dBm Range -20dBm ±0.5dBm ±10% of meter indication

-30dBm Range -30dBm ±0.5dBm ±10% of meter indication

-50dBm Range -50dBm ±0.5dBm ±10% of meter indication

CARRIER 135 BAL

LEVEL ACCURACY CHECK

1kHz to 600kHz

+10dBm Range +10dBm ±0.5dBm

-10dBm Range -10dBm ±0.5dBm

-20dBm Range -20dBm ±0.5dBm

-30dBm Range -30dBm ±0.5dBm

-40dBm Range -40dBm ±0.5dBm

-50dBm Range -50dBm ±0.5dBm

10kHz to 300kHz

+10dBm Range +10dBm ±0.2dBm

-10dBm Range -10dBm ±0.2dBm

-20dBm Range -20dBm ±0.2dBm

-30dBm Range -30dBm ±0.2dBm

-40dBm Range -40dBm ±0.2dBm

-50dBm Range -50dBm ±0.2dBm

0dBm Range 0dBm ±0.5dBm ±10% of meter indication

40dBm Range -40dBm ±0.5dBm ±10% of meter indication

0dBm Range 0dBm ±0.5dBm

0dBm Range 0dBm ±0.2dBm

(1)

CARRIER 600 BAL

LEVEL ACCURACY CHECK

1kHz to 150kHz

+10dBm Range +10dBm ±0.5dBm

0dBm Range 0dBm ±0.5dBm

-10dBm Range -10dBm ±0.5dBm

-20dBm Range -20dBm ±0.5dBm

-30dBm Range -30dBm ±0.5dBm

-40dBm Range -40dBm ±0.5dBm

-50dBm Range -50dBm ±0.5dBm

10kHz to 100kHz

+10dBm Range +10dBm ±0.2dBm

0dBm Range 0dBm ±0.2dBm

-10dBm Range -10dBm ±0.2dBm

-20dBm Range -20dBm ±0.2dBm

-30dBm Range -30dBm ±0.2dBm

-40dBm Range -40dBm ±0.2dBm

-50dBm Range -50dBm ±0.2dBm

VF/Nm 600 BAL and 900 BAL

LEVEL ACCURACY CHECK

20Hz to 20kHz 600 ohms 900 ohms

0dBm Range 0dBm ±0.5dBm

-10dBm Range -10dBm ±0.5dBm

-20dBm Range -20dBm ±0.5dBm

-30dBm Range -30dBm ±0.5dBm

-40dBm Range -40dBm ±0.5dBm

-50dBm Range -50dBm ±0.5dBm

-60dBm Range -60dBm ±0.5dBm

-70dBm Range -70dBm ±0.5dBm

-80dBm Range -80dBm ±0.5dBm

PERFORMANCE CHECK TEST CARD (Cont'd)

40Hz to 1SkHz

100Hz to 20kHz

+30dBm Range +30dBm 0±0.5dBm +20dBm Range +20dBm ±0.5dBm +10dBm Range +l0dBm ±0.5dBm

100Hz to 15kHz

+30dBm Range +30dBm ±0.2dBm +20dBm Range +20dBm ±0.2dBm +10dBm Range +10dBm ±0.2dBm

0dBm Range 0dBm ±0.2dBm

-10dBm Range -10dBm ±0.2dBm

-20dBm Range -20dBm ±0.2dBm

-30dBm Range -30dBm ±0.2dBm

-40dBm Range -40dBm ±0.2dBm

-50dBm Range -50dBm ±0.2dBm

-60dBm Range -60dBm ±0.2dBm

(2)

PERFORMANCE CHECK TEST CARD (Cont'd)

RETURN LOSS CHECK 600 ohms 900 ohms

VF/Nm

30Hz to 20kHz >30dB

CARRIER

600 ohms, 1kHz to 150kHz >26dB 135 ohms, 1kHz to 600kHz > 26dB

75 ohms, 1kHz to 3MHz >30dB

FILTER RESPONSE CHECKS

C-MSG

60Hz -55.7dBm ±2dBm 200Hz -25dBm ±2dBm 500Hz -7.5dBm ±1dBm 1kHz 0dBm (Ref) 2kHz -1.3dBm ±1dBm

2.5kHz -1.4dBm ±2dBm 4kHz -14.5dBm ±3dBm 5kHz -28.5dBm ±3dBm

3kHz FLAT

60Hz 0dBm ±1.75dBm 250Hz 0dBm ±1dBm 1kHz 0dBm (Ref) 2kHz -0.5dBm ±1.75dBm

2.5kHz -1.5dBm ±2dBm 3kHz -3dBm ±3dBm

15kHz FLAT

60Hz 0dBm ±1.75dBm 250Hz 0dBm ±1dBm 1kHz 0dBm (Ref) 5kHz 0dBm ±1dBm 10kHz -0.5dBm ±1.75dBm

12.5kHz -1.5dBm ±2dBm 15kHz -3dBm ±3dBm

PROGRAM

200Hz -17.3dBm ±2dBm 500Hz -6.6dBm ±1dBm 1kHz 0dBm (Ref) 2kHz +4.8dBm ±2dBm 4kHz +6.5dBm ±2dBm 5kHz +6.5dBm ±2dBm 6kHz +6.4dBm ±3dBm 8kHz +4dBm ±3dBm 10kHz -8.5dBm ±4dBm

BRIDGING LOSS CHECK

VF/Nm 900 BAL, 1kHz 0.3dBm VF/Nm 600 BAL, 1kHz <0.3dBm CARRIER 600 BAL, 10kHz <.05dBm

INPUT BALANCE CHECK

VF/Nm 600 BAL

60Hz >80dB 6kHz >70dB 20kHz >50dB

CARRIER 600 BAL

1kHz to 10kHz >70dB 1kHz to 100kHz >60dB 1kHz to 600kHz >40dB

(3)

Model 3555B Section VI

digit code. (See Appendix A for list of

Miscellaneous parts are listed at the end of

(Table 6-2). Order the part through normal channels. If

SECTION VI

REPLACEABLE PARTS

6-1. INTRODUCTION.

c. Typical manufacturer of the part in a five6-2. This section contains information for ordering replacement parts. Table 6-1 lists parts in alphameric order of their reference designators and indicates the description, -hp- part number of each part, together with any applicable notes, and provides the following:

a. Total quantity used in the instrument (TQ

column). The total quantity of a part is given the first time the part number appears.

6-3. Table 6-1.

6-4. ORDERING INFORMATION.

6-5. To order a part, note the manufacturer's part number (Table 6-1, MFR PART NO.) and then cross reference that number in the cross-reference index

manufacturers.)

d. Manufacturer's part number.

b. Description of the part. (See list of

abbreviations below.)

the NSN is not listed for the part in Table 6-2, order by MFR PART NO. and the manufacturer's identification number listed under the MFR number in Table 6-1.

Ag....................................................silver ID.................................... inside diameter ns............nanosecond(s) = 10-9 seconds SPDT ........single-pole double-throw

ABBREVIATIONS

Al..............................................aluminum impg.....................................impregnated nar................. not separately replaceable SPST...........single-pole singe-throw

A..............................................ampere(s) incd.....................................incandescent

Au......................................................gold ins...................................... insulation(ed) Ω .................................................. ohm(s) Ta........................................tantalum

C................................................capacitor kΩ ........................ kilohm(s) = 10+3 ohms OD ................................outside diameter TiO2.........................titanium dioxide

cer...............................................ceramic kHz ..........................kilohertz = 10+3hertz tog ...........................................toggle

coef.........................................coefficient P ......................................................peak tol.......................................tolerance

com........................................... common L..................................................inductor Pa .................................... picoampere(s) trim.......................................trimmer

comp....................................composition lin...........................................linear taper pc.......................................printed circuit TSTR ................................ transistor

conn.......................................connection log.................................logarithmic taper pF.................................picofarad(s) 10

dep...........................................deposited mA.......... milliampere(s) = 10-3 amperes piv ...........................peak inverse voltage vacw....................alternating current

DPDT..............double-pole double-throw MHz .................... megahertz = 10+6 hertz p/o..................................................part of working voltage

DPST ...............double-pole single-throw mΩ ...................megohm(s) = 10+6 ohms pos..........................................position(s) var ........................................variable

elect ....................................... electrolytic mfr......................................manufacturer pot...........................................potiometer

encap.................................encapsulated ms..........................................millisecond p-p.......................................peak-to-peak W ...........................................watt(s)

F..................................................farad(s) mV........................millivolt(s) = 10-3 volts prec..................... precision (temperature wiv...............working inverse voltage

FET.........................field effect transistor µF ...................................... microfarad(s) ........................coefficient, long term sta- w/o......................................... without

fxd.....................................................fixed µs....................................microsecond(s) ............................ bility, and/or tolerance) ww ................................... wirewound

................................................................. µV.......................microvolt(s) = 10-6 volts

GaAs.............................gallium arsenide my.................................................Mylar® R..................................................resistor *..............optimum value selected at

GHz.......................gigahertz = 10+9 hertz Rh ...............................................rhodium factory, average value

gd.............................................guard(ed) nA..........nanoampere(s) = 10-9 amperes rms..............................root-mean-square shown (part may be omitted)

Ge.........................................germanium NC ..................................normally closed rot....................................................rotary ** .............. no standard type number

grd..........................................ground(ed) Ne.................................................... neon assigned (selected or

H.............................................. henry(ies) NPO...................... negative positive zero sect..........................................section(s)

Hg............................................... mercury ..................(zero temperature coefficient) Si....................................................silicon

Hz................. hertz (cycle(s) per second) sl......................................................slide ® Dupont de Nemours

A............................................... assembly FL .....................................................filter Q...............................................transistor TS ............................... terminal strip

B..................................................... motor HR .................................................heater QCR ................................transistor-diode V................. vacuum tube, neon bulb

BT .................................................battery IC..................................integrated circuit R..................................................resistor photocell, etc.

C................................................capacitor J.........................................................jack RT ............................................thermistor W .............................................cable

CT...................................................diode K...................................................... relay S ....................................................switch X.............................................socket

DL.............................................delay line L..................................................inductor T ...........................................transformer XDS................................ lampholder

DS....................................................lamp M.....................................................meter TB.....................................terminal board XF.....................................fuseholder

E...............................misc electronic part MP ................................. mechanical part TC......................................thermocouple Y.............................................crystal

F........................................................fuse P.......................................................plug TP............................................. test point Z...........................................network

met film....................................metal film poly ....................................... polysterene vdcw.. direct current working voltage

mtg ...........................................mounting ppm................................parts per million w/................................................with

NO.................................... normally open Se .............................................selenium special type

Prefix Symbols Multiplier Prefix Symbols Multiplier tear T 10 giga G 10 mega M or Meg 10 kilo K or k 10 hecto h 10 deka da 10 femto f 10 deci d 10

DECMAL MULTIPLIERS

12 9 6 3 2

-1

DESIGNATORS

obd...........................order by description TC............... temperature coefficient

-12

farads V..............................................volt(s)

centi c 10 milli m 10 micro µ 10 nano n 10 pico p 10

atto a 10

-2

-3

-6

-9

-12

-15

-18

6-1

Section VI Model 3555B

Table 6-1. Replaceable Parts

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A1 03555-66507 1 PC Board Ass'y: function -hp-

C1 0170-0055 1 C: fxd mylar 0.1uF +/-20% 200 vdcw 56289 192P10402-PTS C2.C3 0180-0089 2 C: fxd Al elect 10uF +50% -10% 150 vdcw 56289 30D106F150DD2-DSM C4 0121-4105 3 C: var 9-35pF 72982 538-00694D C5* 0160-0205 2 C: fxd mica 10pF +/-5% 72136 RDM15C100J5S C6 0160-2206 1 C: fxd mica 160pF +/-5% 72136 RDM15F161J3C

C7 0121-0105 C: var 9-35pF 72982 53830694D C8* 0140-0204 1 C: fxd mica 47pF +/-5% 72136 DM15E470J0500W1CR C9* 0140-0193 1 C: fxd mica 82pF +/-5% 72136 RDM15E82OJ3C C10 0160-0763 1 C: fxd mica 5pF 10% 14655 RDM15C050K5S obd

R1 0698-0090 2 R: fxd met flm 464 ohms +/-1% 1/2W 91637 MFF-1/2-T-1 obd R2 0811-2846 2 R: fxd ww 300 ohms +/-1% 1/2W -hpR3 0684-2211 3 R: fxd comp 220 ohms +/-10% 1/4W 01121 CB2211 R4 0811-2847 2 R: fxd ww 67.5 ohms +/-1% 1/2W -hpR5,R6 0698-3499 2 R: fxd met flm 40.2 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd

R7 0698-4508 1 R: fxd met flm 78.7 kilohms +/-1% 1/8W 14674 C4 obd R8 0698-4467 1 R: fxd met flm 1.05 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R9 0698-0090 R: fxd met flm 464 ohms +/-1% 1/2W 91637 MFF-1/2-T-1 obd R10 0811-2846 R: fxd ww 300 ohms +/-1% 1/2W -hpR11 0684-2211 R: fxd comp 220 ohms +/-10% 1/4W 01121 CB2211

R12* 0684-4711 1 R: fxd comp 470 ohms +/-10% 1/4W 01121 CB4711 R13 0811-2794 1 R: fxd prec ww 25 kilohms 5% -hpR14* 0684-2211 R: fxd comp 220 ohms +/-10% 1/4W 01121 CB2211 R15 0757-0472 3 R: fxd met flm 200 kilohms +/-1% 1/8W 75042 CEA obd R16 0811-2847 R: fxd ww 67.5 ohms +/-1% 1/2W -hp-

R17 0683-1505 1 R: fxd 15 ohms +/-5% 1/4W 01121 CB1505 S1 3100-1793 1 Switch Ass'y: pushbutton 71590 1332 obd T1 9100-1458 1 Transformer: carrier frequency -hp-

T2 9100-1460 1 Transformer: audio -hpW1 03555-61616 1 Cable Ass'y: function -hp-

A2 03555-66509 1 PC Board Ass'y: range switch -hp-

C1 0121-0128 4 C: var 1.4-9.2pF air trim 74970 189-503-5 C2 0160-0196 2 C: fxd mica 24pF +/-5% 72136 RDM15C240J3S C3 0160-2130 4 C: fxd mica 865pF +/-1% 100 vdcw 72136 RDM15F(865)F1C C4 0121-0128 C: var 1.49.2pF air trim 74970 189-503-5 C5 0160-0196 C: fxd mica 24pF +/-5% 72136 RDM15C240J3S

C6 0160-2130 C: fxd mica 865pF +/-1% 100 vdcw 72136 RDM15F(865)F1C C7 0121-0128 C: var 1.4-9.2pF air trim 74970 189-503-5 †C8 0160-2307 1 C: fxd mica 47pF 5% 00853 RDM15E470J3C †C9 0160-3482 1 C: fxd mica 430pF 1% 300 vdcw 14655 RDM15F431F3C †C10 0160-3586 1 C: fxd mica 43pF 300 vdcw 72136 RDM15E4300D3C

†C11 0160-3083 1 C: fxd mica 62pF 1% 500 V 72136 RDM15D620F5C C12 0121-0128 C: var 1.4-9.2pF air trim 74970 189-503-5

R1 0698-7330 2 R: fxd flm 96.84 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R2 0698-7329 2 R: fxd met firm 3.266 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R3 0684-2701 2 R: fxd comp 27 ohms +1-10% 1/4W 01121 CB2701 R4 0698-7330 R: fxd flm 96.84 kilohms +/0.1% 1/8W 91637 CMF-1/10-32 obd R5 0698-7329 R: fxd met firm 3.266 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd

† See backdating in Appendix C.

6-2

Model 3555B Section VI

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A2 (Cont'd)

R6 0683-1805 1 R: fxd comp 18 ohms +/-5% 1/4W 01121 CB1805 R7 0698-4342 1 R: fxd met flm 90 kilohms +/-0.1% 1/8W 91637 MF-1/10-32 obd R8 0698-4339 1 R: fxd met flm 11.11 kilohms +/-0.1% 1/8W' 91637 MF-1/10-32 obd R9 0698-5095 1 R: fxd carbon comp 12 ohms +/-10% 1/2W 01121 CB1201 R10 0698-7328 1 R: fxd met flm 68.38 kilohms +/-0.1% 1/8W 91637 MF-1/10-32 obd

R11 0698-7331 1 R: met flm 46.28 kilohms +/-0.1% 1/8W 91637 MF-1/10-32 obd R12 Not assigned R13 0698-3150 1 R: fxd met flm 2.37 kilohms +/-1% 1/8W 91637 MF-1/1O 2 obd R14 0698-3264 1 R: fxd met flm 11.8 kilohms +/-1% 1/8W 14674 C4 obd

S1 3100-1791 1 Switch: rotary range 76854 1332 obd

A3 03555-66508 1 Board Ass'y: amplifier -hp-

C1* 0160-0763 2 C: fxd mica 5pF +/-10% 72136 RDM15COFOKSS C2 0180-0197 5 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X902oA2-DYS C3 0180-1746 4 C: fxd Ta elect 15uF +/-10% 20 vdcw 56289 150D156X9020B2-DYS C4 0160-2964 6 C: fxd cer 0.01uF +80% -20% 25 vdcw 72982 5835000.Y5UO-10 32 C5 0160-0205 C: fxd mica 10pF +/-5% 72136 RDM15C100J58S

C6,C7 0160-0378 2 C: fxd mica 27pF +/-5% 72136 RDM15E27OJ5S C8 0121-0105 C: var 9-35pF 72982 538400694D C9 0140-0196 1 C: fxd mica 150pF +/-5% 72136 RDM15F151J3C C10 0180-0228 10 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226K015P1C C11 0180-0106 1 C: fxd Ta 60uF +/-20% 6 vdcw 56289 90803

C12 thru C14 0160-2964 C: fxd cer 0.01uF +80% -20% 25 vdcw 72982 5835000)Y5U-1032 C15* 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226K015P1C C16 0180-0393 3 C: fxd Ta elect 39uF +/-10% -10 vdcw 37942 TAS396KO10PIC C17 0160-2964 C: fxd cer 0.01uF +80% -20% 25 vdcw 72982 5835000.Y5UO-1032 C18 Not assigned

C19 0180-0197 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X9020A2-DYS C20 0160-0763 C: fxd mica 5pF +/-10% 72136 RDM15C050K5SS C21 0180-1702 1 C: fxd Ta elect 180uF +/-20% 6 vdcw 37942 obd C22 0160-2964 C: fxd cer 0.01uF +80% -20% 25 vdcw 72982 5835-000-Y5U0-1032 C23 0180-0197 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X9020A2-DYS

C24 0180-0137 1 C: fxd Ta 100uF +/-20% 10 vdcw 56289 150D107X0010R2-DYS C25 0180-0197 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X9020A2-DYS C26 0150-0011 1 C: fxd TiO2 1.5pF +/-20% 500 vdcw 78488 Type GA obd C27 0180-0393 C: fxd Ta elect 39uF +/-10% -10 vdcw 37942 TAS396KO10P1C C28 0180-0196 1 C: fxd Ta 56uF +/-10% 15 vdcw 37942 TAS566K015P F

C29 0180-0374 1 C: fxd Ta elect 1OuF +/-10% 20 vdcw 37942 TAS106K020F1C C30 thru C32 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226K015PlC C33 0180-0197 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X9020A2-DYS C34 0180-1794 1 C; fxd Ta elect 22uF +/-10% 35 vdcw 56289 150D226X9035R2-DYS C35 thru C37 0180-1746 C: fxd Ta elect 15uF +/-10% 20 vdcw 56289 150D156X9020B2-DYS

CR1,CR2 1901-0376 2 Diode: Si 35 wiv 2pF 07933 RD5288 CR3,CR4 1902-3030 4 Diode: zener 3.01V +/-5% 400mW 20mA 04713 SZ10939-32 CR5 thru CR7 1901-0040 11 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG1O88 CR8 1902-0761 3 Diode: zener 6.2V +/-5% 400mW 7.5mA 04713 Type 1N821 CR9 1902-3030 Diode: zener 3.01V +/-5% 400mW 20mA 04713 SZ1Q939-32

CR10 1901-0040 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG1OB8 CR11 1902-3030 Diode: zener 3.01V +/-5% 400mW 20mA 04713 SZ10939-32 CR12,CR13 1901-0040 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG1088 CR14 1902-0761 Diode: zener 6.2V +/-5% 400mW 7.5mA 04713 Type 1N821 CR15,CR16 1901-0040 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG1088

CR17 1901-0025 7 Diode: Si 100 wiv 12pF 10mA 24446 SS410 CR18,CR19 1901-0040 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG10O88

6-3

Section VI Model 3555B

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A3 (Cont'd)

CR20 1902-1275 Diode: zener 6.2V +/-5% 400mW 7.5mA 04713 Type 1N821 CR21 1901 0040 Diode: Si 30 wiv 2pF 30mA 2ns 07263 FDG1088

K1 thru K3 0490-0780 3 Relay Ass'y: reed -hp-

0490-0778 3 Reeds 95348 MR5830 L1 9100-1637 1 Inductor: fxd 120uH +/-5% 82142 15-1315-14J Q1 1853-0086 7 TSTR: Si PNP 2N5087 04713 SPS-3322

Q2, Q3 1853-0036 9 TSTR: Si PNP 2N3906 04713 SPS-3612 Q4 1854-0215 3 TSTR: Si NPN 2N3904 04713 SPS-3611 Q5 thru Q8 1853-0036 TSTR: Si PNP 2N3906 04713 SPS-3612 Q9 1854-0215 TSTR: Si NPN 2N3904 04713 SPS-3611 Q10 1853-0036 TSTR: Si PNP 2N3906 04713 SPS-3612

Q11 1855-0057 1 TSTR: Si FET N channel Type A 04713 SS-3651 Q12 1853-0036 TSTR: Si PNP 2N3906 04713 SPS-3612 Q13 1854-0092 2 TSTR: NPN 2N3563 04713 MPS-3563 Q14 1853-0049 2 TSTR: Si PNP 04713 -hpQ15 1854-0215 TSTR: Si NPN 2N3904 04713 SPS-3611

Q16 1853-4049 TSTR: Si PNP 04713 -hpQ17 1854-0401 1 TSTR: NPN 04713 -hpQ18,Q19 1853-0235 3 TSTR: Si PNP 2N3547 12040 NS62048 Q20 1854-0022 1 TSTR: NPN 01295 SG1294 Q21 1853-0235 TSTR: Si PNP 2N3547 12040 NS62048

Q22 1853-0037 1 TSTR: Si PNP 04713 2N2904A R1 0757-0334 1 R: fxd met flm 301 ohms +/-1% 1/4W 91637 MF-1/8-44 obd

R2 0698-4521 2 R: fxd met flm 154 kilohms +/-1% 1/8W 14674 C4 obd R3 0698-4533 1 R: fxd met flm 294 kilohms +/-1% 1/8W 14674 C4 obd R4 0684-4731 2 R: fxd comp 47 kilohms +/-10% 1/4W 01121 CB4731 R5 0684-1221 2 R: fxd comp 1.2 kilohms +/-10% 1/4W 01121 CB1221 R6 0684-1011 5 R: fxd comp 100 ohms +/-10% 1/4W 01121 CB1011 R7,R8 0684-2241 2 R: fxd comp 220 kilohms +/-10% 1/4W 01121 C82241 R9 0684-4721 3 R: fxd comp 4700 ohms +/-10% 1/4W 01121 CB4721 R10 0684-1011 R: fxd comp 100 ohms +/-10% 1/4W 01121 CB1011 R11 0698-7375 3 R: fxd met flm 28.64 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd

R12 0684-1011 R: fxd comp 100 ohms +/-10% 1/4W 01121 CB1011 R13,R14 0757-0273 2 R: fxd met flm 3.01 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R15 2100-2829 1 R: var carbon comp 500 ohms +/-30%

R16 0698-4458 1 R: fxd met flm 590 ohms +/-1% 1/8W 14674 C4 obd R17 0684-1011 R: fxd comp l00 ohms +/-10% 1/4W 01121 CB1011

R18 0684-1041 1 R: fxd comp 100 kilohms +/-10% 1/4W 01121 CB1041 R19 0698-3154 1 R: fxd met flm 4.22 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R20 2100-2829 R: var carbon comp 5 kilohms +/-30% 71590 Type E8-83716 R21 0698-3155 1 R: fxd metflm 4.64 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R22 0698-4405 1 R: fxd met flm 107 ohms +/-1% 1i8W 14674 C4 obd

R23 0684-2221 1 R: fxd comp 2200 ohms +/-10% 1/4W 01121 CB2221 R24 2100-2829 R: var carbon comp 500 ohms +/-30% 71590 Type E8-83716 R25 0698-4014 1 R: fxd met flm 787 ohms +/-1% 1/8W 14674 C4 obd R26 2100-2829 R: var carbon comp 500 ohms +/-30% 71590 Type E883716 R27 0698-4521 R: fxd met flm 154 kilohms +/-1% 1/8W 14674 C4 obd R28,R29 Not assigned R30 0684-3341 1 R: fxd comp 330 kilohms +/-10% 1/4W 01121 CB3341 R31 0684-1541 3 R: fxd comp 150 kilohms +/-10% 1/4W 01121 CB1541 R32 0684-1011 R: fxd comp 100 ohms +/-10% 1/4W 01121 CB1011 R33 0684-1221 R: fxd comp 1.2 kilohms +/-10% 1/4W 01121 CB1221

R34 0684-1021 6 R: fxd comp 1O000 ohms +/-10% 1/4W 01121 C81021 R35,R36 0684-1541 R: fxd comp 150 kilohms +/-10% 1/4W 01121 CB1541 R37 0684-4721 R: fxd comp 4700 ohms +/-10% 114W 01121 C84721 R38 0698-4454 1 R: fxd met flm 523 ohms +/-1% 1/8W 91637 MF-1/10-32 obd R39 0684-3921 3 R: fxd comp 3900 ohms +/-10% 1/4W 01121 CB3921

1/4W 4 sec type V 71590 Type E8-83716

6-4

Model 3555B Section VI

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A3 (Cont'd)

R40 0684 4721 R: fxd comp 4700 ohms +/-10% 1/4W 01121 CB4721 R41,R42 0698-3382 2 R: fxd met flm 5.49 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R43 2100-1770 1 R: var ww 00 ohm +/-10O% 1/2W trimmer 80294 3-365P-E88-101 R44 0698-3223 1 R: fxd met flm 1.24 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R45 0684-2231 3 R: fxd comp 22 kilohms +/-10% 1/4W 01121 CB2231

R46* 0684-3921 R: fxd comp 3900 ohms +/-10% 1/4W 01121 CB3921 R47 0684-8211 2 R: fxd comp 820 ohms +/-10% 1/4W 01121 CB8211 R48 0684-2231 R: fxd comp 22 kilohms +/-10% 1/4W 01121 CB2231 R49 0757-4442 3 R: fxd met flm 10 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R50 0684-1031 2 R: fxd comp 10 kilohm +/-10% 1/4W 01121 CB1031

R51 0084-8211 R: fxd comp 820 ohm +/-10% 1/4W 01121 CB8211 R52 0767-0280 R: fxd met flm 1 kilohm +/-1% 1/8W 91637 CMF-1/10-32 obd R53,R54 0684-1211 2 R: fxd comp 120 ohm +/-10% 1/4W 01121 CB1211 R55 0757-0442 R: fxd met flm 10 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R56 thru R58 Not assigned

R59 0757-4468 1 R: fxd met flm 130 kilohm +/-1% 1/8W 14674 C4 obd R60 0684-3331 1 R: fxd comp 33 kilohms +/-106 1/4W 01121 CB3331 R61 0684-1001 3 R: fxd comp 10 ohm +/-10O% 1/4W 01121 CB1001 R62 0684-3921 R: fxd comp 3900 ohms +/-10% 1/4W 01121 CB3921 R63 0684-1031 R: fxd comp 10 kilohms +/-10O 1/4W 01121 CB1031

R64 0684-2231 R: fxd comp 22 kilohms +/-10% 1/4W 01121 CB2231 R65 thru R67 0684-1021 R: fxd comp 1000 ohms +/-10% 1/4W 01121 CB1021 R68 0698-4503 1 R: fxd met flm 66.5 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R69 0698-4491 1 R: fxd met flm 30.9 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R70,R71 06841001 R: fxd comp 10 ohm +/-10% 1/4W 01121 CBI001

R72* 0684-2701 R: fxd comp 27 ohm +/-10% 1/4W 01121 CB2701 R73 0684-1021 R: fxd comp 1000 ohm +/-10% 1/4W 01121 CB1021 R74*,R75* 0684-8221 2 R: fxd comp 8200 ohm +/-10% 1/4W 01121 CB8221

XA1 1251-1941 1 Connector: PC 6 pin 71785 252-06-30-310 W1 0355-61616 1 Cable -hp-

A4 03555-66506 1 PC Board Ass'y: filter -hp-

C1 0140-0177 1 C: fxd mica 400pF +/-1% 72136 RDM15F3C C2 0180-0291 4 C: fxd Ta elect 1uF +/-10% 35 vdcw 56289 150D105X9035A2-DYS C3,C4 0160-2130 C: fxd mice 865pF +/-1% 100 vdcw 72136 RDM15F(865)F1C C5 0140-0203 5 C: fxd mica 30pF +/-5% 72136 RDM15F421F3C C6 0180-0228 C: fxd elect 22uF +/-10% 15 vdcw 37942 TAS226K015PlC

C7 0140-0163 6 C: fxd mice 4751pF +/-1% 300 vdcw 72136 RDM20F(4751)F3S C8 0160-3024 4 C: fxd mica 1700pF +/-1% 100 vdcw 72136 RDM19F 72F1S C9 0140-0203 C: fxd mice 30pF +/-5% 72138 RDM15F421F3C C10 0160-3024 C: fxd mice 1700pF +/-1% 100 vdcw 72138 RDM19F172F1S C11 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226KOlPlC

C12 0140-0163 C: fxd mica 4751pF +/-1% 300 vdcw 72136 RDM20F(4751)F3S C13 thru C15 Not assigned C16 0160-3024 C: fxd mice 1700pF +/-1% 100 vdcw 72136 RDM19F172F1S C17 0140-0203 C: fxd mica 30pF +/-5% 72136 RDM15F421F3C C18 0160-3024 C: fxd mica 1700pF +/-1% 100 vdcw 72136 RDM19F172F1S

C19 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226KO15P1C C20,C21 0180-0291 C: fxd Ta elect 1uF +/-10% 35 vdcw 56289 15OD105X9035A2-DYS C22 Not assigned C23 0180-0197 C: fxd Ta 2.2uF +/-10% 20 vdcw 56289 150D225X9020A2-DYS C24 0140-0163 C: fxd mica 4751pF +/-1% 300 vdcw 72136 RDM20F(4751)F3S

C25 0140-0203 C: fxd mice 30pF +I-5% 72136 RDM15F421F3C C26 0140-0163 C: fxd mice 4751pF +/-1% 300 vdcw 72136 RDM20F(4751)F3S C27 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226K01SPIC C28,C29 0140-0163 C: fxd mica 4751pF +/-1% 300 vdcw 72136 RDM20F(4751)F3S C30 0140-0203 C: fxd mice 30pF +/-5% 72136 RDM15F421F3C

6-5

Section VI Model 3555B

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A4 (Cont'd)

C31 0180-0228 C: fxd Ta elect 22uF +/-10% 15 vdcw 37942 TAS226K015P1C C32 0180-0291 C: fxd Ta elect 1uF +/-10% 35 vdcw 56289 150D105X9035A2-DYS C33 0180-0387 1 C: fxd Ta elect 47uF +/-5% 20 vdcw 37942 TAS476J020P1F

CR1 thru CR5 1901-0026 Diode: Si 100 wiv 12pF 100mA 24446 SS410 Q1,Q2 1854-0071 16 TSTR: Si NPN 2N3391 01296 SKA1124

Q3 1853-0086 6 TSTR: Si PNP 2N5087 04713 SPS-3322 Q4,Q5 1854-0071 TSTR: Si NPN 2N3391 01296 SKA1124 Q6 1853-0086 TSTR: Si PNP 2N5087 04713 SPS-3322 Q7,Q8 1854-0071 TSTR: Si NPN 2N3391 01296 SKA1124

Q9 1853-0086 TSTR: Si PNP 2N5087 04713 SPS-3322 Q10 thru Q12 1854-0071 TSTR: Si NPN 2N3391 01295 SKA1124 Q13 1853-0086 TSTR: Si PNP 2N50B7 04713 SPS-3322 Q14 thru Q16 1854-0071 TSTR: Si NPN 2N3391 01295 SKA1124 Q17 1853-0086 TSTR: Si PNP 2N5087 04713 SPS-3322

Q18 thru Q20 1854-0071 TSTR: Si NPN 2N3391 01295 SKA1124 Q21 1853-0086 TSTR: Si PNP 2N5087 04713 SPS-3322 Q22 1854-0071 TSTR: Si NPN 2N3391 01296 SKA1124

R1 0757-0450 2 R: fxd et flm 22.1 kilohms +/-1% 118W 75042 CEA obd R2 0038-4412 1 R: fxd met flm 17.4 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R3 2100-0406 1 R: var carbon comp 5 kilohms +/30% 4 sec 71590 Series 5 Type 70-4 R4 0698-7373 1 R: fxd met flm 98.941 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R5,R6 0698-7374 2 R: fxd met flm 217Jkilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd

R7(A/B/C) 1810-0027 5 R: carbon flm network 2X1OOK 10 kilohms +/-10% 56289 178C5 R8 0698-7372 1 R: fxd met flm 108.94 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R9 0698-7376 1 R: fxd met flm 11.397 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R10 0698-6313 5 R: fxd met flm 20 kilohms +/-0.1% 118W 91637 CMF-1/10-32 obd R11 0698-7375 R: fxd met flm 28.640 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd

R12,R13 0757-0476 2 R: fxd met flm 301 kilohms +/-1% 1/8W 14674 C4 obd R14 0684-6821 1 R: fxd comp 6800 ohms +/-10% 1/4W 01121 CB6821 R15 0604-4731 R: fxd comp 47 kilohms +/-10% 11/4W 01121 C84731 R16* 0698-3557 1 R: fxd met flm 806 ohms +/-1% 1/8W 14674 C4 obd R17 0698-3519 1 R: fxd met flm 12.4 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd

R18* 0757-0443 1 R: fxd met flm 11 kilohms +/-1% 1/8W 14674 C4 obd R19 Not assigned R20 0698-7375 R: fxd met flm 28.640 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R21(A/B/C) 1810-0027 R: carbon flm network 2X100K 10 kilohms +/-10% 56289 178C5 R22 07570451 1 R: fxd met flm 24.3 kilohms +/-1% 1/8W 14674 C4 obd

R23 0757-0450 R: fxd met flm 22.1 kilohms +/-1% 1/8W 75042 CEA obd R24 0698-0043 R: fxd met flm 20 kilohms +/4.1% 1/8W 91637 CMF-1/10-32 obd R25 0638-1407 1 R: fxd met flm 44.2 kilohms +/-1% 1/8W 14674 C4 obd R26(A/B/C) 1810-0027 R: carbon flm network 2X100K 10 kilohms +/-10% 56289 178C5 R27 0698-7365 1 R: fxd me flm 13.394 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd

R28 0038 6043 R: fxd met flm 20 kilohms +/4).1% 91637 CMF-1/1032 obd R29 0757-0465 1 R: fxd met flm 100 kilohms +/-1% 1/8W 14674 C4 obd R30,R31 0684-1051 3 R: fxd comp 1 megohm +/-10% 1/4W 01121 C81051 R32 0757-0280 2 R: fxd met flm 1 kilohm +/-1% 1/8W 91637 CMF-1/10-32 obd R33 0757-0442 R: fxd met flm 10 kilohm +/-1% 1/8W 91637 MF-1/10-32 obd

R34 0757-0448 1 R: fxd met flm 1&2 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R35,R36 0757-0472 R: fxd met flm 200 kilohms +/-1% 1/8W 75042 CEA obd R37,R38 0698-7366 2 R: fxd met flm 109.64.kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R39(A/B/C) 1810-0027 R: carbon flm network 2X100K 10 kilohms +/-10% 56289 178C5 R40 0638-0043 R: fxd met flm 20 kilohm +/-.1% 91637 CMF-1/10-32 obd

R41 0698-7367 1 R: fxd met flm 78.028 kilohms +-0.1% 1/8W 91637 CMF-1/1032 obd R42,R43 0698-7369 2 R: fxd met flm 73803 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R44(A/B/C) 1810-0027 R: carbon flm network 2X100K 10 kilohms +/-10% 56289 178C5 R45 0698-7368 1 R: fxd met flm 36.901 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R46 0698-6943 R: fxd met flm 20 kilohms +/-0.1% 91637 CMF-1/10-32 obd

6-6

Model 3555B Section VI

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

A4 (Cont'd)

R47 0698-7370 1 R: fxd met flm 17.579 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R48 0684-1051 R: fxd comp 1 megohm +/-10% 1/4W 01121 CB1051 R49 0684-1021 R: fxd comp 1000 ohms +/-10% 1/4W 01121 CB1021

03565-60104 1 Chassis Ass’y: power supply -hp-

CHASSIS MOUNTED COMPONENTS

BT1 1420-0026 1 Battery: 45V 83740 No. 482 C1 0180-2230 1 C: fxd A1 elect 150uF - 10% + 100% 200 vdcw 56289 62D10046-DFP

C2 0180-0149 1 C: fxd A1 elect 65uF 60 vdcw hpC3 0180-0393 C: fxd Ta elect 39uF +/-10% -10 vdcw 37942 TAS396K010P1C C4* 0160-0987 1 C: fxd mica 12pF +/-5% 72136 RDM15C120J5S C5 0150-0023 1 C: fxd cer 2000oF +/-20% 1000 vdcw 56289 20C295A2-CDH C6 0160-0195 1 C: fxd cer 1000 pF 20% 250 vac 56289 19C251A1-CDH

CR1-4 1901-0025 4 Diode: Si 100 wiv 12pF 100mA 24446 SS410 CR6 1901-0040 1 Diode: Si 30 V 50 mA -hp-

DS1,DS2 2140-0298 2 Neon lamp 74276 A230 F1 2110-0320 2 Fuse: 0.15A 125V Slo-Blo 71400 MDL 15/100

J1 1251-2357 1 Connector: AC power cord receptacle 82389 EAC-301 J2 1251-1900 4 Jack: telephone 82389 22A obd J3 1200-0163 1 Receptacle: 5 pin 74868 78PCG5 J4 1251-1144 1 Jack: telephone 82389 MT-342B J5 1251-1143 Jack: telephone 82389 MT-332B

J6,J7 1251-0065 4 Jack: telephone 82389 MT-331 J8,J9 1510-0084 2 Binding post: red -hpJ10 1510-0087 1 Binding post Ass'y -hpJ11 1510-0531 1 Binding post Ass'y -hpJ12,J13 1251-0065 Jack: telephone 82389 MT-331

J14 1251-1143 Jack: telephone 82389 MT-332B J17 1250-1053 1 Jack: coaxial 70674 CJ-1010

J18 1251-1143 Jack: telephone 82389 MT-332B L1 9100-1390 1 Inductor: audio -hp-

L2 9140-0088 1 Inductor: fxd .33uH +%-5% 200mA 95262 NB 0.37 PS M1 1120-0909 1 Meter: log calibrated -hp-

1400-0085 2 Holder: fuse 75915 342004

6-7

Section VI Model 3555B

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

CHASSIS MOUNTED COMPONENTS (Cont'd)

03555-67902 1 Power Supply Ass'y -hp-

R1 0757-0795 1 R: fxd met flm 75 ohms +/-1% 1/2W 91637 MFF-1/2-T-1 obd R2 0698-4205 1 R: fxd met flm 21 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R3 0698-7371 2 R: fxd met flm 20.605 kilohms +/-0.1% 1/8W 91637 CMF-1/10-32 obd R4 0698-3158 2 R: fxd met flm 23.7 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R5 0698-4488 1 R: fxd met flm 26.7 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd

R6 0698-7371 R: fxd met flm 20.605 kilohms +/-0.1% 91637 CMF-1/10-32 obd R7 0757-0290 1 R: fxd met flm 6.19 kilohms +/-1% 1/8W 14674 C4 obd R8 0698-3158 R: fxd met flm 23.7 kilohms +/-1% 1/8W 91637 MF-1/10-32 obd R9 0698-3245 1 R: fxd flm 20.5 kilohms +/-1% 1/8W 14674 Cr obd R10 0757-0455 1 R: fxd met flm 36.5 kilohms +/-1% 1/8W 14674 C4 obd

R11 0698-4434 1 R: fxd met firm 2.32 kilohms +/-1% 1/8W 91637 CMF-1/10-32 obd S1 3100-1794 1 Switch: lever, input 76854 1332 obd

S2 03555-61904 1 Switch Ass'y: weighting -hpS3 3101 0045 1 Switch: slide 82389 11A-1014A S4,S5 3101 -0001 2 Switch: toggle SPST 04009 80994-HB S6 3101-1234 1 Switch: slide DPDT 82389 11A-1242A

T1 9100-1457 1 Transformer: power -hpW1 03555-69503 1 Cable Ass'y -hp-

W2 03555-69504 1 Cable Ass'y -hpW3 03555-69502 1 Cable Ass'y -hpW4 03555-69505 1 Cable Ass'y -hpW5 Not assigned

W6 03555-69501 1 Cable Ass'y -hpW7 03555-61611 1 Cable Ass'y: interconnecting and range -hp-

MISCELLANEOUS

0340-0099 4 Insulator: binding post -hp0340-0100 2 Insulator: binding post single -hp0370-0035 1 Knob: bar w/arrow black -hp0370-0046 2 Knob: lever switch, black -hp0370-0440 8 Knob: pushbuttons, grey -hp-

1390-0137 4 Washer: retaining 1/4 turn fastener 71286 2600-1W 1390-0186 4 Stud: 1/4 turn fastener 71286 265424 1400-0062 1 Clip: cable 78553 C21891-017-24 1400-0076 2 Clip: fuse 75915 101002 1520-0001 1 Wafer: cap plate mtg 4 lug 56137 Grade X-831

4040-0476 1 Insulator: jack -hp5000-7126 1 Decal: pushbutton "75 UNBAL" -hp5000-7134 1 Decal: pushbutton "135 BAL" -hp5000-7135 1 Decal: pushbutton "150 BAL" -hp5000-7136 2 Decal: pushbutton "600 BAL" -hp5000-7138 1 Decal: pushbutton "HOLD" -hp5000-7139 1 Decal: pushbutton "DIAL-BAT" -hp5000-7140 1 Decal: pushbutton "NG" -hp5000-7147 1 Decal: pushbutton "900 BAL" -hp8120-1518 1 Cord Set: power 70903 obd

6-8

Model 3555B Section VI

Table 6-1. Replaceable Parts (Cont'd)

REFERENCE -hp- TQ DESCRIPTION MFR. MFR. PART NO.

DESIGNATOR PART NO.

MISCELLANEOUS (Cont'd)

1251-1145 1 Plug: battery 72825 7364 525C-49A 2 Handle: panel -hp00236-04105 1 Cover: battery -hp1390-0186 Stud: fastener cadmium plated steel 71286 26542-4 00741-01212 2 Bracket: meter -hp03555-00206 1 Panel: front -hp03555-00204 1 Panel: sub -hp0340-0732 1 Insul: Bdg Post -hp-

03555-26510 1 Test board: blank -hp03555-60604 1 Shield Ass'y: amplifier -hp03555-61204 1 Retainer Ass'y: cord/headphone -hp0355541203 1 Retainer: headphone -hp-

03556-64507 1 Cover: assembly -hp03556-64508 1 Case Assembly -hp03556-90007 1 Manual: operating and service -hp-

6-9

TM 11-6625-2779-14&P

TABLE 6-2.

PART NUMBER - NATIONAL STOCK NUMBER

CROSS REFERENCE INDEX

REPLACEMENT

NATIONAL NATIONAL

PART STOCK PART STOCK

NUMBER FSCM NUMBER NUMBER FSCM NUMBER

CB1001 01121 5905-00-989-8653 RCR07G100JS 81349 5905-00-107-0656 CB1041 01121 5905-00-254-7432 RCRO7G104JS 81349 5905-00-110-0388 CB1541 01121 5905-00-726-5345 RCR07G154JS 81349 5905-00-114-5339 CB1805 01121 5905-00-833-0718 RCR07G180JS 81349 5905-00-115-7953 CB2211 01121 5905-00-721-0131 RCR07G221JS 81349 5905-00-135-3973 CB2221 01121 5905-00-726-6433 RCR07G222JS 81349 5905-00-105-7764 CB3921 01121 5905-00-755-0795 RCR07G392JS 81349 5905-00-141-0743 CB4731 01121 5905-00-985-5609 RCR07G473JS 81349 5905-00-141-0717 CB6821 01121 5905-00-721-0671 RCR07G682JS 81349 5905-00-110-7622 CB8211 01121 5905-00-755-0796 RCR07G821JS 81349 5905-00-119-8768 CB8221 01121 5905-00-721-0674 RCR07G822JS 81349 5905-00-104-8358 EAC-301 82389 5935-00-233-6728 MDL15/100 71400 5920-00-665-3074 F03B250V15-100A 81349 5920-00-661-0530 MPS-3563 04713 5961-00-122-8671 MT-331 82389 5935-00-201-8993 JJ086 81349 5935-00-192-4826 MT-332-B 82389 5935-00-192-4825 MT-3428 82389 5935-00-500-7439 RD5288 07933 5961-00-222-6128 RD5288 49956 5961-00-222-6128 SKA1124 01295 5961-00-137-4608 SPS3322 04713 5961-00-224-5601 SPS3611 04713 5961-00-137-0966 SPS3612 04713 5961-00-137-0967 SS3651 04713 5961-00-137-0999 TAS396K015PIC 37942 5910-00-816-2474 M39003-01-2979 81349 5910-00-192-7180 TYPE-GA 78488 5910-00-577-1219 GAO-47PFPORM5PCT 78488 5910-00-834-9437 TYPE-LN821 04713 5961-00-804-7548 JAN1N821 81349 5961-00-866-5454 0698-4521 28480 5905-00-489-2050 LLA-1014A 82389 5930-00-402-6752 11A-1242A 82389 5930-00-406-8746 150D107X0010R2D 56289 5910-00-850-0830 19C251AL-CDH 56289 5910-00-852-2644 192P10402-PTS 56289 5910-00-797-9742 192P10452 56289 5910-00-984-2845 2N2904A 04713 5961-00-941-2056 2600-1W 71286 5325-00-449-3024 78PCG5 74868 5935-00-919-6391 78PCG5 02660 5935-00-919-6391 80994-HB 04009 5930-00-929-1970

6-10

6-11

Model 3555B Appendix A

6-12

CODE LIST OF MANUFACTURERS (Continued)

6-13

Model 3555B Section VII

SECTION VII

CIRCUIT DIAGRAMS

7-1. INTRODUCTION.

7-2. This section of the Manual contains circuit diagrams for the Model 3555B Transmission and Noise Measuring Set. The functional block diagram (Figure 7-

1) contains signal levels to assist in troubleshooting. The schematic diagrams (Figures 7-2 through 7-5) show dc voltage levels which should also aid in locating faulty components.

7-3. FUNCTIONAL BLOCK DIAGRAM.

7-4. The functional block diagram (Figure 7-1) of the 3555B serves the dual purpose of showing how various circuits are arranged to form the set and at the same time gives voltages and adjustments for use in troubleshooting the set. This functional block diagram

REFERENCE DESIGNATIONS

should be used in conjunction with the troubleshooting procedure described in Section V.

7-5. SCHEMATIC DIAGRAMS.

7-6. The schematic diagrams (Figures 7-2 through 7-

5) contained in this section show the detailed circuits in the Model 3555B. Components marked with an asterisk are those that are critical in value. The value of these components may vary slightly from one set to another due to variations in transistor Beta etc, and the values shown on the schematic are average.

7-7. Voltage levels have been included on the schematics which should greatly assist in troubleshooting the set. When measuring these voltages a high input impedance voltmeter (1 megohm or greater) should be used to prevent circuit loading.

7-1

Section VII Model 3555B

7-2

Figure 7-1. Functional Block Diagram

7-3/7-4

Figure 7-2. A1 Function Assembly Schematic and Component Location

7-5/7-6

Figure 7-3. A2 Range Attenuator and A3 Input Amplifier Schematic and Component Location

7-7/7-8

Figure 7-4. A4 Filter Schematic and Component Location

7-9/7-10

Figure 7-5. A3 Meter Amplifier, Detector and Series Regulator Schematic and Component Locations

7-11/7-12

APPENDIX A

REFERENCES

DA Pam 310-4 Index of Technical Manuals, Technical Bulletins, Supply Manuals (Types 7, 8, and 9), Supply

Bulletins and Lubrication Orders. DA Pam 310-7 US Army Equipment Index of Modification Work Orders. TM 11-6625-320-12 Operator’s and Organizational Maintenance Manual: Voltmeters ME-30A/U, and voltmeters,

Electronic, ME-30B/U, ME-30C/U and ME30E/U. TM 11-6625-683-15 Operator’s Organizational, Direct Support, General Support and Depot Maintenance Manual:

Signal Generator AN/URM-127 (NSN 6625-00-783-5965). TM 11-6625-2953-14 Operator’s, Organizational, Direct Support, and General Support Maintenance Manual:

Multimeter AN/USM-451 (NSN 6625-01-060-6804). TM 38-750 The Army Maintenance Management System (TAMMS). TM 740-90-1 Administrative Storage of Equipment. TM 750-244-2 Procedures for Destruction of Electronics Materiel to Prevent Enemy Use (Electronics

Command).

A-1

APPENDIX B

MAINTENANCE ALLOCATION

Section I. INTRODUCTION

B-1. General

This appendix provides a summary of the maintenance operations for TA-885/U. It authorizes categories of maintenance for specific maintenance functions on repairable items and components and the tools and equipment required to perform each function. This appendix may be used as an aid in planning maintenance operations.

B-2. Maintenance Function

Maintenance function will be limited to and defined as follows:

a. Inspect. To determine the serviceability of an item by comparing its physical, mechanical, and/or electrical characteristics with established standards through examination.

b. Test. To verify serviceability and to detect incipient failure by measuring the mechanical or electrical characteristics of an item and comparing those characteristics with prescribed standards.

c. Service. Operations required periodically to keep an item in proper operating condition, i.e., to clean (decontaminate), to preserve, to drain, to paint, or to replenish fuel, lubricants, hydraulic fluids, or compressed air supplies.

d. Adjust. To maintain, within prescribed limits, by bringing into proper or exact position, or by setting the operating characteristics to the specified parameters.

e. Align. To adjust specified variable elements of an item to bring about optimum or desired performance.

f. Calibrate. To determine and cause corrections to be made or to be adjusted on instruments or test measuring and diagnostic equipments used in precision measurement. Consists of comparisons of two instruments, one of which is a certified standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instrument being compared.

g. Install. The act of emplacing, seating, or fixing into position an item, part, module (component or assembly) in a manner to allow the proper functioning of the equipment or system.

h. Replace. The act of substituting a serviceable like type part, subassembly, or module (component or assembly) for an unserviceable counterpart.

i. Repair. The application of maintenance services (inspect, test, service, adjust, align, calibrate, replace) or other maintenance actions (welding, grinding, riveting, straightening, facing, remachining, or resurfacing) to restore serviceability to an item by correcting specific, damage, fault, malfunction, or failure in a part, subassembly, module (component or assembly), end item, or system.

j. Overhaul. That maintenance effort (service/action) necessary to restore an item to a completely serviceable/operational condition as prescribed by maintenance standards (i.e., DMWR) in appropriate technical publications. Overhaul is normally the highest degree of maintenance performed by the Army. Overhaul does not normally return an item to like new condition.

k. Rebuild. Consists of those services/actions necessary for the restoration of serviceable equipment to a like new condition in accordance with original manufacturing standards. Rebuild is the highest degree of materiel maintenance applied to Army equipment. The rebuild operation includes the act of returning to zero those age measurements (hours, miles, etc.) considered in classifying Army equipments/components.

B-3. Column Entries

a. Column 1, Group Number. Column 1 lists group numbers, the purpose of which is to identify components, assemblies, subassemblies, and modules with the next higher assembly.

b. Column 2, Component/Assembly. Column 2 contains the noun names of components, assemblies, subassemblies, and modules for which maintenance is authorized.

c. Column 3, Maintenance Functions. Column 3 lists the functions to be performed on the item listed in column 2. When items are listed without maintenance functions, it is solely for purpose of having the group numbers in the MAC and RPSTL coincide.

d. Column 4, Maintenance Category. Column 4 specifies, by the listing of a "work time" figure in the appropriate subcolumn(s), the lowest level of maintenance authorized to perform the function listed in column 3. This figure represents the active time required to perform that maintenance function at the indicated category of maintenance. If the number or complexity of the tasks within the listed maintenance function vary at different maintenance categories, appropriate "work time" figures will be shown for each category. The number of taskhours specified by the "work time" figure represents the average time required to restore an item (assembly, subassembly, component, module, end item or system) to a serviceable condition under typical field operating conditions. This time includes preparation time, troubleshooting time, and quality assurance/quality control time in addition to the time required to perform the specific tasks identified for the maintenance functions authorized in the maintenance allocation chart. Subcolumn of column 4 are as follows:

C - Operator/Crew

O - Organizational

B-1

F - Direct Support H - General Support D - Depot

e. Column 5, Tools and Equipment. Column 5 specifies by code those common tool sets (not individual tools) and special tools, test, and support equipment required to perform the designated function.

f. Column 6, Remarks. Column 6 contains an alphabetic code which leads to the remark in section IV, Remarks, which is pertinent to the item opposite the particular code.

B-4. Tool and Test Equipment Requirements (Sec

III)

a. Tool or Test Equipment Reference Code. The number in this column coincide with the numbers used in the tools and equipment column of the MAC. The numbers indicate the applicable tool or test equipment for the maintenance functions.

(Next printed page B-3)

b. Maintenance Category. The codes in this column indicate the maintenance category allocated the tool or test equipment

c. Nomenclature. This column lists the noun name and nomenclature of the tools and test equipment required to perform the maintenance functions.

d. National/NATO Stock Number. This column lists the National/NATO stock number of the specific tool or test equipment.

e. Tool Number. This column lists the manufacturer's part number of the tool followed by the Federal Supply Code for manufacturers (5-digit) in parentheses.

B-5. Remarks (Sec IV)

a. Reference Code. This code refers to the appropriate item in section II, column 6.

b. Remarks. This column provides the required explanatory information necessary to clarify items appearing in section II.

B-2

SECTION II. MAINTENANCE ALLOCATION CHART

FOR

AUDIO LEVEL METER TA-885/U

TM 11-6625-2779-14&P

(1) (2) (3) (4) (5) (6)

GROUP MAINTENANCE TOOLS AND

NUMBER COMPONENT ASSEMBLY FUNCTION C O F H D EQUIPMENT REMARKS

00 AUDIO LEVEL METER TA-885/U Inspect 0.5 7

(HP 3555B) Test 0.5 1 thru 7

Service 0.8 1 thru 7 Repair 1.2 1 thru 7 Overhaul 2.0 1 thru 7

MAINTENANCE CATEGORY

B-3

TM 11-7725-2779-14&P

SECTION III. TOOL AND TEST EQUIPMENT REQUIREMENTS

FOR

AUDIO LEVEL METER TA-885/U

TOOL OR

TEST MAINTENANCE NATIONAL/ TOOL

EQUIPMENT CATEGORY NOMENCLATURE NATO STOCK NUMBER

REF CODE NUMBER

1 H,D OSCILLATOR SG-1128/U, HP #654A 6625-00-450-7590 2 H,D OSCILLATOR AN/URM-127 6625-00-783-5965 3 H,D TRANSFORMER (LINE MATCHING) MX-8385/U 6625-00-567-5837 4 H,D MULTIMETER AN/USM-451 6625-01-060-6804 5 H,D AMPLIFIER HP-467A 6625-00-458-2480 6 H,D VOLTMETER, ELECTRONIC ME-30 E/U 6625-00-643-1670 7 O COMMON TOOLS NECESSARY TO THE PERFORMANCE OF

THIS MAINTENANCE FUNCTION ARE AVAILABLE TO MAINTENANCE PERSONNEL FOR THE MAINTENANCE CATEGORY LISTED.

B-4

Model 3555B APPENDIX C Appendix C

MANUAL BACKDATING CHANGES

Model 3555B

TRANSMISSION AND NOISE MEASURING SET

This manual backdating sheet makes this manual applicable to earlier instruments. Instrument-component values that differ from those in the manual, yet are not listed in the backdating sheet, should be replaced using the part number given in the manual.

Instrument Serial Prefix Make Manual Changes Instrument Serial Prefix Make Manual Changes 916-00500 and below 1 thru 7 0992A03537 and below 7 916-00509 and below 2 thru 7 953-00544 and below 3 thru 7 953-00825 and below 4 thru 7 0992A01395 and below 5 thru 7 0992A03536 and below 6, 7

Change No. 1

In instruments with S/N 916-00500 and below CR1 and C2 in the power supply were located as shown in the following figure:

Change No. 2

Table 6-1 and figure 7-3, change:

Change No. 3

Figure 7-4, change the pin connections as follows: 7 to 6, 13 to 12, 16 to 15, 15 to 13. Instruments with serial numbers 953)00544 and below had a 03555-66506 Revision A board in them. This board is not interchangeable with the Revision B board. The above pin connections are for the Revision A board.

Change No. 4

Delete S6 in figure 7-5 and in Table 6-1. Earlier instruments did not have this switch. See the following figure

A2C8 to 33pF, part no. 0160-2150 A2C9 to 320pF, part no. 0140-0226 A2C10 to 39pF, part no. 01400175 A2C11 to 51 pF, part no. 0160-2201

for earlier instruments.

C-1

Appendix C Model 3555B

Change part no. of the case assembly to 03555-04505. Change cover part no. to 03555-04504. Table 6-1.

Change the part no. of the power cord to 81 20-0249. Change the part no. of the power connector J1 to 1251-0148.

Change No. 5

Table 6-1. Change to the following gray parts:

Cover, battery 00236-04104 Bracket, meter 00741-0 1209 Panel, front 03555-00203 Assy. cover 03555-64504 Assy. case 03555-64506 Knob, pushbutton 0370-0440

Change No. 6

Page 6-7. Change C2 to 0180-0110, 8 µF

Delete CR2 -4 1901-0025. Page 6-8. Change T1 part no. to 9100-1457. Figure 7-5. Delete CR2 -4 from the Power Supply Rectifier.

Change No. 7

Page 6-7. Delete CR6, 1901-0040. Figure 7-5. Delete CR6 across M1.

*U.S. GOVERNMENT PRINTING OFFICE: 1980-603-128/66

C-2

By Order of the Secretary of the Army:

E. C. MEYER

General, United States Army

Official: Chief of Staff

J. C. PENNINGTON

Major General, United States Army

The Adjutant General

DISTRIBUTION:

Active Army:

HISA (Ft Monmouth) (21) USAICS (3) USAINSCOM (2) MAAG (1) COE (1) USARMIS (1) TSG (1) USAERDAA (1) USAARENBD (1) USAERDAW (1) DARCOM (1) Ft Carson (5) TRADOC (2) Ft Gillem (10) OS Maj Comd (4) Ft Gordon (10) TECOM (2) (CERCOM Ofc) USACC (4) USA Dep (1) MDW (1) Sig Sec USA Dep (1) Armies (2) Army Dep (1) except Corps (2) LBAD (14) Svc Colleges (1) SAAD (30) USASIGS (5) TOAD (14) USAADS (2) SHAD (3) USAFAS (2) Units org under fol TOE: USAIS (2) 29-207 (2) USAFS (2) 29-610 (2)

ARNG: None USAR: None

For explanation of abbreviations used, see AR 310-50.

PIN: 043606-000

HP TM 11-6625-2779-14-P User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

SECTION 0

SECTION I

SECTION II

SECTION III

SECTION IV

SECTION V

SECTION VI

SECTION VII

APPENDIX A

APPENDIX B

Model 3555B APPENDIX C Appendix C