Tektronix 488 schematic

TM 11-6625-3135-12

TECHNICAL MANUAL

OPERATOR’S AND ORGANIZATIONAL

MAINTENANCE MANUAL

OSCILLOSCOPE

AN/USM-488

(NSN 6625 -01-1 87-7847)

This copy is a reprint which includes current pages from Change 1.

HEADQUARTERS, DEPARTMENT OF THE ARMY

1 OCTOBER 1986

TM 11-6625-3135-12

SAFETY STEPS TO FOLLOW IF SOMEONE IS THE VICTIM OF ELECTRICAL SHOCK

DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL

IF POSSIBLE, TURN OFF THE ELECTRICAL POWER

IF YOU CANNOT TURN OFF THE ELECTRICAL POWER, PULL, PUSH, OR LIFT THE PERSON TO SAFETY USING A WOODEN POLE OR A ROPE OR SOME OTHER INSULATING MATERIAL

SEND FOR HELP AS SOON AS POSSIBLE

AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF ELECTRICAL SHOCK, MOVE THE PERSONA SHORT

DISTANCE AWAY AND IMMEDIATELY START ARTIFICIAL RESUSCITATION

TM 11-6625-3135-12

WARNING

HIGH VOLTAGE

is used in the operation of this equipment

DEATH ON CONTACT

may result if personnel fail to observe safety precautions

Never work on electronic equipment unless there is another person nearby who is familiar with the opera! ion and hazards of the equipment and who is competent in administering first aid. When the technician is aided by operators, they must be warned about dangerous areas.

A periodic review of safety precautions in TB 385-4, Safety Precautions for Maintenance of Electrical/Electronic Equipment, is recommended. When the equipment is operated with covers removed, DO NOT TOUCH exposed connections or components. MAKE CERTAIN you are not

grounded when making connections or adjusting components inside the test instrument.

Be careful not to contact high-voltage connections or 115 volt ac input connections when

installing or operating this equipment.

Whenever the nature of the operation permits, keep one hand away from the equipment to reduce

the hazard of current flowing through the body.

WARNING Do not be misled by the term “low voltage”. Potentials as low as

50 volts may cause death under adverse conditions.

For Artficial Respiration. refer to FM 21-11.

TM 11-6625-3135-12

Technical Manual No. 11-6625-3135-12

DEPARTMENT OF THE ARMY

Washington, DC, 1 October 1986

HEADQUARTERS

OPERATOR’S AND ORGANIZATIONAL MAINTENANCE MANUAL

FOR

OSCILLOSCOPE AN/USM-488

(NSN 6625-01-187-7847)

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, DA Form 2028 (Recommended Changes to

Publications and Blank Forms), or DA Form 2028-2 located in the back of this manual direct to:

Commander, US Army Communications-Electronics Command and Fort Monmouth, ATTN:

AMSEL-LC-LM-LT, Fort Monmouth, New Jersey 07703-5000. In either case, a reply will be

furnished direct to you.

Page

HOW TO USE THIS MANUAL . . . . . . . . . . . . . . . . . . . . .

CHAPTER 1

INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . . . . . . .

Section I General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II EQUIPPMENT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

III Technical Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

iii 1-1 1-1 1-4 1-10

CHAPTER 2

OPERATING INSTRUCTIONS

. . . . . . . . . . . . . . . . .

Section I Description and Use of Operator’s Controls and Indicators . . . . . . . . . .

II Operator Preventive Maintenance Checks and Services (PMCS) . . . . . .

III Operation Under Usual Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV Operation Under Unusual Conditions

CHAPTER 3

Section I

III

ORGANIZATIONAL MAINTENANCE INSTRUCTIONS

Repair Parts, Special Tools; (TMDE); and Support Equipment . . . . . .

Service Upon Receipt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maintenance Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparation for Storage or Shipment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

APPENDIX A

B C

SUBJECT INDEX

. . . .

2-1 2-2 2-8 2-11 2-44

3-1 3-1 3-2 3-3 3-5

3-12 A-1

B-1 C-1

D-1 I-1

Change 1

i/(ii blank)

TM 11-6625-3135-12

HOW TO USE THIS MANUAL

This manual tells you about your Oscilloscope AN/USM-488 and contains instructions about how to use it while testing and maintaining other equipment.

The technical manual for the equipment you are maintaining will give you some guidance in the correct method to make certain connections

when testing and troubleshooting with the oscilloscope.

When you first receive your oscilloscope, start at the front of the manual and go all the way through to the back, and become familiar with every part of the manual and the oscilloscope.

This manual has an edge index which will help you find specific information in a hurry. Simply spread the pages on the right edge of the manual until the printed blocks can be seen. Open the manual where the block on the edge of the page lines up with your selected topic printed in the front cover block.

iii

TM 11-6625-3135-12

1-0

Figure 1-1. Oscilloscope AN/USM-488

TM 11-6625-3135-12

CHAPTER 1

INTRODUCTION

Para Page

1-1

Consolidated Index of Army Publications and Blank Forms. . . . . . . . . . . . . . . . .

Destruction of Army Materiel to Prevent Enemy Use . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Euipment Characteristics, Capabilities, and Features. . . . . . . . . . . . . . . . . . . . . . . .

Euipment Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

List of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Location and Description of Major Components . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maintenance Forms,Records,and Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Nomenclature Cross-Reference List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparation for Storage or Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reporting Equipment Improvement Recommendations (EIR) . . . . . . . . . . . . . .

Safety, Care, and Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-2 1-4 1-11 1-13 1-14 1-10 1-12 1-3 1-7 1-5 1-8 1-6 1-1 1-9

1-1 1-4 1-6 1-10 1-3 1-4 1-1 1-1 1-1 1-1 1-1 1-1 1-2

Section I. GENERAL INFORMATION

1-1.SCOPE

This manual describes the Oscilloscope AN/USM-488 (oscilloscope) and provides instructions for operation, cleaning, inspection, and maintenance. Testing, troubleshooting, and repair procedures are provided for organizational maintenance personnel. The oscilloscope (fig. 1-1) is a portable, bench-type oscilloscope designed for general purpose waveform measurements using single-or dual-trace displays with normal or delayed sweep.

1-2. CONSOLIDATED INDEX OF ARMY PUBLICATIONS AND BLANK FORMS

Refer to the latest issue of DA Pam 25-30 to determine whether there are new editions, changes, or additional publications pertaining to the equipment.

1-3. MAINTENANCE FORMS, RECORDS, AND REPORTS

Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and procedures used for equipment maintenance will be those prescribed by DA Pam738-750, as contained in Maintenance Management Update.

Reporting of ltem and Packaging Discrepancies. Fill out and forward SF 364 (Report of Discrepancy

(ROD)) as prescribed in AR 735-11-2/DLAR 4140.55/SECNAVINST 4355.18/AFR 400-54/MCO 4430.3J.

Transportation Discrepancy Report (TDR) (SF 361). Fill out and forward Transportation Discrepancy

Report (TDR) (SF 361) as prescribed in AR 55–38/NAVSUPINST 4610.33C/AFR 75-18/MCO P4610.19D/DLAR

4500.15.

1-4. DESTRUCTION OF ARMY ELECTRONICS MATERIEL TO PREVENT ENEMY USE

Destruction of Army electronics materiel to prevent enemy use shall be in accordance with TM 750-244-2.

1-5. PREPARATION FOR STORAGE OR SHIPMENT

Storage and shipment procedures are in Chapter 3, Section V.

1-6. SAFETY, CARE, AND HANDLING

Observe all WARNINGS, CAUTIONS, and NOTES in this manual. This equipment can be extremely dangerous if these instructions are not followed.

1-7. NOMENCLATURE CROSS-REFERENCE LIST

This listing identifies approved nomenclature usage that is different from the official nomenclature:

Common Name

Osccilloscope . . . . . . . . . . . . . . . . . . . . . . . . . .Oscilloscope AN/USM-488

Official Nomenclature

Change 1 1-1

TM 11-6625-3135-12

1-8. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR)

If your oscillscope 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 or performance. Put it on an SF 368 (Product Quality Deficiency Report). Mail it to: Commander, US Army Communications-Electronics Command and

Fort Monmouth, ATTN: AMSEL-ED-PH, Fort Monmouth, New Jersey 07703-5000. We’ll send you a reply.

1-9. WARRANTY INFORMATION

Oscilloscope AN/USM488 is warranted by Tektronix Inc. for 1 year. The warranty starts on the date of purchase by the original owner. Report all defects immaterial or workmanship to your supervisor who will take appropriate action through your organizational maintenance shop.

1-2

TM 11-6625-3135-12

1-10. LIST OF ABBREVIATIONS

This list identifies abbreviations, and descriptions that are used in this manual,

Abbreviation

AN/USM. . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . .

BII

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . .

crt . . . . . . . . . . . . . . ..

DA . . . . . . . . . . . . . . . . . . .

DOD . . . . . . . . . . . . . . . . .

DISREP . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . .

div

EAR . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . .

kHz . . . . . . . . . . . . . . . . . .

MAC . . . . . . . . . . . . . . . .

MHz . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . ..

...... . . . . . . . . . .

NON . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . ....

pF. .... . . . . ... . . . .

P-P.

. . . . . . . . . . . . . . . . . . . . . .

PMCS . . . . . . . . . . . . . . .

rqr . . . . . . . . . . . . . . . . . . .

. ..... . . . .... . ...

sec/div . . . . . . . . . . . . . . .

SIR . . . . . . . . . . . . . . . . .

TAMES . . . . . . . . . . . . .

TIDE . . . . . . . . . . . . . . .

U/M . . . . . . . . . . . . . . . . .

..... ... ... ...

. . . . . . . . . .

VITS . . . . . . . . ..... .

Army-Navy/General utility-special-maintenance Army Regulation basic issue item Bandwidth operator/crew centimeter cathode ray tube Department of the Army Department of Defense discrepancy in shipment report division equipment improvement recommendation hertz (formerly cps) kilohertz maintenance allocation chart megahertz millivolt nanosecond National/NATO stock number organizational maintenance picofarad peak-to-peak preventive maintenance checks and services required second seconds per division source, maintainability, and recoverability The Army Maintenance Management System test, measurement, and diagnostic equipment unit of measure microsecond microvolt vertical interval test signal

Term

1-3

TM 11-6625-3135-12

Section Il. EQUIPMENT DESCRIPTION

1-11. EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES

The oscilloscope is a rugged, lightweight, dual-channel instrument allowing visual evaluation of electrical circuits.

a. Characteristics.

Measures ac voltage and dc voltage Measures frequency Measures nondelayed time Measures rise and fall times Algebraically adds signals applied to channels 1 and 2

b. Capabilities and Features.

Vertical system provides calibrated deflection factors from 2 inV per division to 5 V per division Trigger circuits enable stable triggering over full bandwidth of vertical system

Horizontal system provides calibrated sweep speeds from 0.5s per division to 50 ns per division Horizontal system provides delayed sweep feature

. Magnifier circuit extends maximum sweep speed to 5 ns per division

1-12. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS

OSCILLOSCOPE (1) evaluation of electrical circuits. It measures and indicates various electrical characteristics needed to test and troubleshoot electrical equipment. The handle can be adjusted as a stand.

POUCH (2) AC POWER CORD (3)

1X PROBE PACKAGE (4) —

— Provides storage for probes and small components.

— A self-contained, multi-range measuring instrument that allows visual

— Provides for operation from the ac power line.

Provides nonattenuated input to oscilloscope.

10X PROBE PACKAGE (5) –

VIEWING HOOD (6) —

COVER (7)

1-4

— Protects crt screen and front panel controls.

Allows operator to view crt display in bright light.

Attenuates input signal by factor of 10.

TM 11-6625-3135-12

1-5

TM 11-6625-3135-12

1-13. EQUIPMENT DATA VERTICAL DEFLECTION SYSTEM:

Deflection Factor

Range Accuracy at 52-95°F(15-350C) ±2% Accuracy at 32-122°F(0-50

Range of VOLTS/DIV Control . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

C). . . . . . . .. ±3%

2 m V to 5 V per division

Continuously variable between settings, Increases deflection factor by at least 2.5 to 1

Step Response (Rise Time)

32-95° F (0-35° C)

5 mV to 5 V per Division . . . . . . . . . . . . . . . . . 3.5 ns or less

2 m V per Division . . . . . . . . . . . . . . . . . . . . . . . . 3.9 ns or less

52-122° F (35-50° C)

5 mV to 5 V per Division . . . . . . . . . . . . . . . . . 3.9 ns or less

2 m V per Division, . . . . . . . . . . . . . . . . . . . . . . . 4.4 ns or less

Aberrations (Positive-going Step)

2 m V to 0.5 V per Division . . . . . . . . . . . . . . . . . 4% peak-to-peak

1 V to 5 V per Division . . . . . . . . . . . . . . . . . . . . . 12% peak-to-peak

Bandwidth (-3 dB Point)

32-95° F (0-35° C)

5 m V to5 V per Division ..... . . . . . . . . . . . dc to at least 100 MHz

2 m V per Division . . . . . . . . . . . . . . . . . . . . . . . . dc to at least 90 MHz

95-122° F (35-500C)

5 m V to 5 V per Division . . . . . . . . . . . . . . . . . dc to at least 90 MHz

2 m V per Division . . . . . . . . . . . . . . . . . . . . . . . . dc to at least 80 MHz

AC Coupled Lower Limit . . . . . . . . . . . . . . . . . . . 10 Hz or less at -3 dB

Bandwidth Limiter

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Upper limits (-3 dB bandpass at 20 MHz, ± 10%)

Chop Mode Switching Rate . . . . . . . . . . . . . . . . . . . 500 kHz ±30%

Input Characteristics

Resistance

.. . . . . . . . . .

Capacitance

. . . . ... . . . . ..... . . . . . . . . . . .

1 Megohm ±2%

20 pF ±2 pF Maximum Safe Input Voltage

DC Coupled

. . . . . . . . . . . . . . . . . . .. . ..

400 V (dc + peak ac) or 800 V peak-to-peak to 10 kHz or less

AC Coupled . . . . . . . . . . . .. . . . .. . .

400 V (dc + peak ac) or 800 V peak-to-peak to 10

kHz or less

Common Mode Rejection Ratio . . . . . . . . . . . . . . At least 20 to 1 at 80 MHz

Input Current . .. . . .. . . . . . . . . . . . .

1.0 nA or less (0.5 division trace shift at 2 m V per

division)

Trace Shift with VOLTS/DIV Switch

Rotation

. . . . . . . . . . . . .

0.75 division or less

Trace Shift as VOLTS/DIV Variable Control

is Rotated

. . .. . . . . . . . . . . . . . . . . . . .

1.0 division or less

Trace Shift With Invert. . . . . . . .. . .. . .. . .. . 1.5 divisions or less

Channel Isolation

POSITION Control Range .............

. . . . . . . . . . . .

Greater than 100 to 1 at 50 MHz At least ±11 divisions from graticule center

1-6

TRIGGER SYSTEM:

A Trigger Sensitivity

P-P AUTO/TV LINE and NORM Modes

Internal . . . . . . . . . . . . . . . . . . . . . . ..

0.35 division at 10 MHz, 1.0 division at 60 MHz,

1.5 divisions at 100 MHz

External

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35 m V at 10 MHz, 120 m V at 60 MHz, 150 m V at

100 MHz

High-Frequency Rejection . . . . . . . . . . . . . . . .

Attenuates signals above 40 kHz (-3 dB point at 40 kHz ±25%)

Low-Frequency Rejection . . . . . . . . . . . . . . . .

Attenuates signals below 40 kHz

(--3 dB point at 40 kHz ±25%)

Lowest Useable Frequency in P-P

AUTO Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TV FIELD Mode . . . . . . . . . . . . . . . . . . . . . . . . . . .

20 Hz with 1.0 division internal or 100 m V external

1.0 division of composite sync

External Trigger Input

Maximum Input Voltage . . . . . . . . . . . . . . . . . . .

Input Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Input Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . .

AC Coupled . . . . . . . . . . . . . . . . . . . . . . . . . . .

400 V (dc + peak ac) or 800 V ac peak-to-peak

1 Megohm ±2%

20 pF ±2.5 pF

10 Hz or less at lower -3 dB point

Level Control Range

A TRIGGER (Normal)

INT . . . . . .

. . . . ... . . . . . . . . . . . . . . .

. . . . . . . . . .

Can be set to any point of the trace that can be displayed

EXT. DC EXT. DC 10

. . . . . . . . . . . . . . . . . . . . . . .... . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . .

B TRIGGER (Internal) . . . . . . . . . . . . . . . . . . . . .

At least+ 1.6 V (3.2 V peak-to-peak) At least ±16 V (32 V peak-to-peak) Can be set to any point of trace that can be displayed

VAR HOLDOFF Control

. . . . . . . . . . . . . . . . . .

Increases A sweep holdoff time by at least a factor of 10

TM 11-6625-3135-12

TRIGGER VIEW SYSTEM:

Deflection Factor

Internal

. . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .

Same as vertical

External

AC and DC

. . . . . . . . . . . . . . . . . . . ...... ...

DC 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

100 m V per division 1 V per division

±20%

Delay Difference Between EXT INPUT and

Either Vertical Channel . . . . . . . . . . . . . . ...

Less than 2.0 ns

1-7

TM 11-6625-3135-12

HORIZONTAL DEFLECTION SYSTEM:

Sweep Rate Calibrated Range

A sleep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0.5 second to 0.05 us per division. X10 magnifier extends maximum sweep speed to 5 ns per division

B Sweep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50 ms to0.05us per division. X10 magnifier extends maximum sweep speed to 5 ns per division

Sweep Rate Accuracy at 59-95° F (15-35° C)... Sweep Rate Accuracy at 32-122° F (0-50° C)...

POSITION Control Range . . . . . . . . . . . . . . . . . . . .

±2% unmagnified, ±3% magnified ±3% unmagnified, ±4% magnified Start of sweep to 10th division will position past center vertical graticule line in X1 or 100th division in X10

Sweep Linearity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5%

Variable Control Range . . . . . . . . . . . . . . . . . . . . . . .

Continuously variable between calibrated settings. Reduces A and B sweep speeds by at least a factor of 2.5

Sweep Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Greater than 10 divisions

A/B SWP SEP Range . . . . . . . . . . . . . . . . . . . . . . . . ±3.5 divisions or greater

Delay Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dial Control Range . . . . . . . . . . . . . . . . . . . . . . . . .

Jitter . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . .

Applies to 0.5 us per division and slower

<0.5 + 300 ns to >10 divisions

0.005% of the maximum delay time

Time Measurement Accuracy

59-95° F (15-350 C) . . . . . . . . . . . . . . . . . . . . . . . . ±1%+ 0.01 major dial division

32-122° F (0-50

C) . . . . . . . . . . . . . . . . . . . . . . . . ±2%+ 0.01 major dial division

X-Y OPERATION:

Deflection Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Same as vertical deflection system (with VOLTS/DIV variable controls in CAL detent)

Accuracy

X-Axis at 59-95° F (15-35 X-Axis at 32-122° F (0-50

Y-Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C) . . . . . . . . . . . . . . . ±3%

C) . . . . . . . . . . . . . . . ±4%

Same as vertical deflection system

Bandwidth (--3 dB Point)

X-Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dc to at least 2.5 MHz

Y-Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Same as vertical deflection system

Phase Difference Between X- and Y-Axis

Amplifiers, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±3%from dcto150kHz

AMPLITUDE CALIBRATOR:

Output Voltage of AMP CAL Connector . . . . . 0.5V ±2%

Repetition Rate................ . . . . . . . . . . . 1 kHz ±20%

Z-AXIS INPUT:

Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 V causes noticeable modulation. Positive-going input decreases intensity. Useable frequency range is dc to 20 MHz.

Maximum Safe Input Voltage . . . . . . . . . . . . . . . . .

30 V (dc + peak) or 30 V ac peak-to-peak at

1 kHz or less

Input Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 kilo hms ±10%

1-8

POWER SOURCE:

Line Voltage Ranges . . . . . . . . . . . . . . . . . . . . . . . . . .

Line Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maximum Power Consumption . . . . . . . . . . . . . . .

Line Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

90 V ac to 250 V ac 48 to 440 Hz 40 W (70 VA)

1.0 A, 250 V, Slow-blow

CATHODE RAY TUBE:

Display Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Standard Phosphor

. . . . . . . . . . . . . . . . . . . . . . . . . . .

Nominal Accelerating Voltage . . . . . . . . . . . . . . . . .

80mmx100mm

P31 14 kV

ENVIRONMENTAL CHARACTERISTICS:

Operating Temperature . . . . . . . . . . . . . . . . . . . . . . .

Nonoperating Temperature . . . . . . . . . . . . . . . . . . .

Operating Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32-122° F (0-50° C)

-67 to +167°F (--55 to + 75°C) Up to 15,000 ft (4,500m). Maximum temperature

decreased 1° C per 1,000 ft above 5,000 ft

Nonoperating Altitude . . . . . . . . . . . . . . . . . . . . . . . .

Operating Humidity

. . . . . . . . . . . . . . . . . . . . ... . . .

Nonoperating Humidity . . . . . . . . . . . . . . . . . . . . . . .

Vibration (Operating) . . . . . . . . . . . . . . . . . . . . . . . . .

To 50,000 ft (15,000 m)

95% at 86-122° F (30-50° C)

95% at 86-140° F (30-60° C)

Can withstand total displacement of 0.01 5 inch

p-p (2.4 g’s at 55 Hz) along all three axes, with

frequency varied from 10 Hz to 55 Hz, for period

of 15 minutes

Electromagnetic Interference . . . . . . . . . . . . . . . . . .

Meets requirements of MIL STD-461B Pt 4

TM 11-6625-3135-12

PHYSICAL CHARACTERISTICS:

Weight with Accessories . . . . . . . . . . . . . . . . . . . . . . .

Weight without Accessories . . . . . . . . . . . . . . . . . . .

Domestic Shipping Weight . . . . . . . . . . . . . . . . . . . .

Height with Empty Pouch . . . . . . . . . . . . . . . . . . . . .

Height without Pouch . . . . . . . . . . . . . . . . . . . . . . . . .

Width with Handle

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Width without Handle . . . . . . . . . . . . . . . . . . . . . . . .

Length with Front Cover . . . . . . . . . . . . . . . . . . . . . .

Length without Front Cover.. . . . . . . . . . . . . . . . .

Length with Handle Extended . . . . . . . . . . . . . . . . .

20.0 lb (9.1 kg)

13.5 lb (6.1 kg)

24.1 lb (10.9 kg)

5.9 in. (150 mm)

5.4 in. (137 mm)

14.2 in. (360 mm)

12.9 in. (328 mm)

17.5 in. (445 mm)

17.3 in. (440 mm)

20.1 in. (511 mm)

1-9

TM 11-6625-3135-12

Section Ill. TECHNICAL PRINCIPLES OF OPERATION

1-14. FUNCTIONAL DESCRIPTION

The following is a basic functional description of the oscilloscope. Refer to fig. 1-2 for a block diagram.

There are two vertical attenuators (one for each channel). The attenuator circuits provide control of input coupling, vertical deflection factor, and variable volts-per-division gain. An invert circuit in the channel 2 attenuator allows you to invert the channel 2 input signal.

The vertical preamp and output circuit amplifies the input signals. This makes the signal level high enough for vertical deflection of the electron beam in the crt. The dynamic range of the amplifier can be limited with the beam find switch. The amplifier also intensifies the trace and limits horizontal deflection.

The A sweep generator and logic circuit produces a linear voltage ramp for horizontal deflection of the crt beam. The sweep generator also produces signals that generate correct timing of the crt unblinking and intensity levels.

The A trigger circuitry uses either an internal signal, external trigger, or ac line trigger signal to develop a gate signal for the A sweep generator. The B trigger circuitry uses only the internal trigger signal to gate the B signal generator.

The alternate B sweep circuitry produces a linear voltage ramp that is amplified by the horizontal amplifier. This provides the B sweep horizontal deflection on the crt. The alternate B sweep circuitry also produces sweep-switching signals that control the display of the A and B sweeps, and gate signals used to establish the crt unblinking and intensity levels for the A intensified and B sweep displays.

The X-Y amplifier amplifies the channel 1 signal from the internal circuit and applies it to the horizontal amplifier. The horizontal amplifier provides output signals to drive the crt horizontal deflection plates.

The power supply converts ac power-line voltage into voltages needed for oscilloscope

operation. The Z-axis amplifier uses several input signal sources to control the crt intensity

level. The crt provides a visual display of the electrical properties of the circuit or signal under

examination.

1-10

TM 11-6625-3135-12

Figure 1-2. AN/USM-488 Oscilloscope Block Diagram

1-11/(1-12 Blank)

CHAPTER 2

OPERATING INSTRUCTIONS

TM 11-6625-3135-12

Para

General Operator Preventive Maintenance Checks and Services . . . . . . . . .

Operating Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operation in Unusual Weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PMCS Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-1 2-3 2-4 2-2

Page

2-8 2-11 2-44 2-8

2-1

TM 11-6625-3135-12

Section I. DESCRIPTION AND USE OF OPERATOR’S CONTROLS

AND INDICATORS

Key

Control Or Indicator

Cathode Ray Tube

A INTENSITY Control

B INTENSITY Control

TRACE ROTATION Control

BEAM FIND Switch

SCALE ILLUM

Control

FOCUS Control

Function

Provides visual display of electrical properties of circuit under examination

Controls brightness of A sweep trace

Controls brightness of B sweep trace

Screwdriver adjustment used to align trace with horizontal

graticule line When held depressed, compresses display to within graticule

area to aid in locating off-screen displays Adjusts brightness of graticule illumination

Adjusts for optimum display definition

2-2

POWER Switch POWER Indicator

Turns oscilloscope power on and off When illuminated, indicates power applied to oscilloscope

TM 11-6625-3135-12

Key

10 11

14 15

Control Or Indicator

POSITION Control UNCAL Indicator

A/B SWP SEP Control

UNCAL Indicator

POSITION Control CH 2 VOLTS/DIV

Switch

CH 2 VOLTS/DIV Variable Control

BW LIMIT Switch

TRIG VIEW Switch

Function

Controls vertical position of channel 1 display When illuminated, indicates channel 1 VOLTS/DIV control

not in calibrated position Vertically positions B sweep trace with respect to A sweep

trace when HORIZONTAL ALT mode is selected When illuminated, indicates channel 2 VOLTS/DIV control

not in calibrated position Controls vertical position of channel 2 display Used to select channel 2 vertical deflection factor

When rotated out of detent, provides variable, uncalibrated deflection factors between calibrated settings of channel 2 VOLTS/DIV switch

When depressed, limits bandwidth of vertical amplifier and

A trigger system to approximately 20 MHz

While held in, sample of signal present in A trigger amplifier displayed on crt

CH 1 VOLTS/DIV

Variable Control

CH 1 VOLTS/DIV Switch

When rotated out of detent, provides variable, uncalibrated deflection factors between calibrated settings of channel 1

VOLTS/DIV switch

Used to select channel 1 vertical deflection factor

2-3

TM 11-6625-3135-12

Key

Control Or Indicator

VERTICAL MODE CH 1/BOTH/CH Switch

22 CH 1 TRIGGER

SOURCE Switch

22-23 COMPOSITE

CH 2 TRIGGER SOURCE Switch

VERTICAL MODE

ADD/ALT/CHOP Switch

Function

When set to CH 1, selects only channel 1 input signal

for display. When set to BOTH, selects both channel 1 and channel 2 input signals for display. When set to CH 2, selects only channel 2 input signal for display

When depressed, selects signal applied to CH 1 OR X INPUT connector as trigger source

When CH 1 and CH 2 switches are either both depressed or both released, composite trigger source is selected, Trigger source is then determined by signals selected for display by the VERTICAL MODE switches

When depressed, selects signal applied to CH 2 OR Y INPUT connector as trigger source

When set to ADD, displays algebraic sum of channel 1 and channel 2 input signals. When set to ALT, displays channel 1 and channel 2 input signals alternately at end of each trace. When set to CHOP, displays channel 1 and channel 2 input signals alternately during sweep time

2-4

AC/GND/DC Switch

Three-position switch to select method of coupling input signal to channel 2 deflection system. It also establishes DC

ground reference line on crt. Three-position switch to select method of coupling input

signal to channel 1 deflection system. It also establishes DC ground reference line on crt.

TM 11-6625-3135-12

Key

30A

30B

Control Or Indicator

UNCAL Indicator

POSITION Control

HORIZONTAL MODE

A/ALT/B Switch

A SEC/DIV Switch B SEC/DIV Switch

Function

When illuminated, indicates SEC/DIV variable control is not in calibrated position

Moves A sweep and B sweep displays horizontally and horizontally positions X-axis in X-Y mode of operation

Determines mode of operation for horizontal deflection system. When set to A, horizontal deflection is provided by A sweep generator. When set to ALT, display alternates between A sweep and B delayed sweep. When set to B, horizontal deflection is provided by B sweep generator

Used to select sweep speeds for A and B sweep generators in a 1, 2, 5 sequence. To lock A and B sweeps together, pull the B SEC/DIV switch out and align the pointer on the B SEC/DIV switch between the two markers on the A SEC/DIV switch, then release the switch. If the two switches are not locked together, B sweep can be delayed. Setting A SEC/DIV switch to X-Y locks the A sweep in horizontal mode.

SEC/DIV Variable Control and X10 Multiplier Switch

B DELAY TIME

POSITION Control

Provides continuously variable, uncalibrated sweep speeds. Pulling control out actuates X 10 magnifier switch, which expands crt display by a factor of 10

Selects amount of delay time between start of A sweep and start of B sweep. Delay time is variable from 0.5 to 10 times A SEC/DIV switch setting

2-5

TM 11-6625-3135-12

Key

35-36

Control Or Indicator

VAR HOLDOFF Control

B TRIGGER LEVEL Control

A TRIGGER NORM Switch

TV FIELD

A TRIGGER

P-P AUTO/TV LINE Switch

A TRIGGER SGL SWP

RESET Switch

Function

Provides continuous control of hold off time between sweeps

and increases hold off time by at least a factor of 10 Selects amplitude point

on trigger signal at which B sweep is

triggered When depressed,

sweep

is initiated when adequate trigger

signal is applied Depressing both P-P

permits triggering on

AUTO and NORM pushbuttons television field signals

Permits triggering on waveforms and television lines having repetition rate of at least 20 Hz. Sweep free-runs in absence of adequate trigger signal

When momentarily depressed, arms A trigger circuit for single-sweep display

2-6

A TRIGGER LEVEL

Control

A EXT

COUPLING

Switch

Selects amplitude point on trigger signal at which A sweep is

triggered

Three-position switch that determines method used to couple external signals from EXT INPUT connector to A trigger circuit

TM11-6625-3135-12

Key

Control Or Indicator

B TRIGGER SLOPE Switch

TRIG’D/READY

Indicator

42 A TRIGGER SLOPE

Switch

A SOURCE Switch

44 A TRIG BW Switch

Function

Selects slope of signal that triggers B channel sweep

Illuminates when either P-P AUTO or NORM trigger mode

is selected Selects slope of signal that triggers A channel sweep

Three-position switch that determines source of trigger signal coupled to input of A trigger circuit. When set to INT, permits triggering on signal applied to CH 1 OR X connector or CH 2 OR Y connector. When set to LINE, selects ac line voltage as trigger signal. When set to EXT, permits triggering on signals applied to EXT INPUT

connector Three-position switch that selects trigger bandpass

frequencies for A trigger circuit. When set to FULL, allows all frequency components to pass. When set to HF REJ, attenuates all trigger signals above approximately 40 kHz. When set to LF REJ, attenuates all trigger signals below approximately 40 kHz

2-7

TM 11-6625-3135-12

Section Il. OPERATOR PREVENTIVE MAINTENANCE CHECKS

AND SERVICES (PMCS)

2-1. GENERAL

Operator Preventive Maintenance Checks and Services (PMCS) is the required inspection and care of your equipment necessary to keep it in good operating condition.

a. Before You Operate.

Always keep in mind the CAUTIONS and WARNINGS. Perform your

before - PMCS.

b. While YOU Operate. Always keep in mind the CAUTIONS and WARNINGS. Perform your

during - PMCS.

c. After Y

OU Operate. Be sure to perform your after-operation PMCS.

d. If Your Equipment Falls to Operate. Troubleshoot with proper equipment. Report any

deficiencies using the proper forms. See DA PAM 738-750.

2-2. PMCS TABLE

The PMCS are shown in table 2-1.

a. Item Number Column. The numbers appearing in this column are in the order the work should be performed. The numbers are keyed to fig. 2-1 to identify work locations. This column shall also be used as a source of item numbers for the TM Number Column on DA Form 2404 (Equipment Inspection and Maintenance Worksheet) in recording results of PMCS.

Interval Column.

This column indicates whether PMCS are performed before operation (B),

during operation (D), after operation (A), or weekly (W).

Item to be Inspected Column. Procedures Column.

This column contains a brief description of the check or service to be

This column identifies the item to be inspected.

performed and step-by-step procedures.

Equipment is Not Ready If Column.

equipment from being ready for operation.

2-8

This column identifies the condition that prevents the

TM 11-6625-3135-12

Table 2-1. Operator Preventive Maintenance Checks and Services

WARNING

High voltage is used in the operation of this equipment. Death on contact may result if you fail to observe safety precautions. Learn where there may be dangerous voltages present.

Item

No.

B = Before

Item to be Inspected

Cabinet Front Panel, and Viewing ‘Hood

Front Panel Controls

Connectors

Carrying Handle

D = During

A = After

Procedure

Inspect case, viewing hood, cover, and front panel for cracks, scratches, deformation, loose or missing hardware or gaskets.

Inspect for missing, loose, or damaged knobs, buttons, and controls.

Inspect for broken shells, cracked insulation, deformed contacts, and dirt in connector.

Inspect for correct operation.

W = Weekly

Equipment is Not Ready if:

Cabinet or front panel is badly damaged.

Knobs, buttons, or controls missing or damaged.

Connector shell is broken, insulation is cracked, or contacts deformed.

AC Power Cord

Inspect for frayed, broken, or abraded insulation, broken wires,

Cord shows any

signs of damage. or damaged connectors. Replace if damaged.

Probe Package

Inspect for missing items, bent pins, broken or frayed cables, and damaged connectors. Replace if damaged.

Cables frayed or broken, pins broken, or connectors damaged.

2-9

TM 11-6625-3135-12

2-10

Figure 2-1. Oscilloscope PMCS Location Diagram

TM 11-6625-3135-12

Section Ill. OPERATION UNDER USUAL CONDITIONS

2-3. OPERATING PROCEDURES

After becoming familiar with the capabilities of the oscilloscope, an operator can easily develop convenient methods for making measurements. The following paragraphs provide recommended methods for making basic measurements, such as probe compensation, voltage measurement, non-delayed time measurement, obtaining television displays, delayed sweep magnification, and delayed sweep time measurements.

a. Obtaining Baseline Trace.

Set POWER ON/ OFF switch (1) to OFF and plug power cord into ac source.

Preset front panel controls as shown in table 2-2.

Depress POWER ON/ OFF switch (1) to ON.

Adjust A INTENSITY control (2) to desired brightness of display. Adjust channel 1 vertical POSITION control (3) to center trace vertically on screen.

5. Adjust horizontal POSITION control (4) to center trace horizontally on screen.

2-11

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