HP 7702b schematic
TM 11-6625-2751-14&P
TECHNICAL MANUAL
OPERATOR’S, ORGANIZATIONAL,
DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL
INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS
FOR
OSCILLOGRAPH RECORDER RO-460(V)1/U
(HEWLETT-PACKARD MODEL 7702B)
(NSN 6625-00-464-2957)
HEADQUARTERS, DEPARTMENT OF THE ARMY
MAY 1979
This manual contains copyright material reproduced by permission of the Hewlett-Packard Company.
TM 11-6625-2751-14&P
TECHNICAL MANUAL HEADQUARTERS
No. 11-6625-2751-14&P WASHINGTON, DC,
OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, AND GENERAL SUPPORT
You can improve this manual by recommending improvements using DA Form 2028-2 located in the
back of the manual. Simply tear out the self-addressed form, fill it out as shown on the sample, fold it
where shown, and drop it in the mail.
If there are no blank DA Forms 2028-2 in the back of your manual, use the standard DA Form 2028
(Recommended Changes to Publications and Blank Forms) and forward to the 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.
}
MAINTENANCE MANUAL INCLUDING
REPAIR PARTS AND SPECIAL TOOLS LISTS
FOR
OSCILLOGRAPH RECORDER RO-460(V)1/U
(HEWLETT-PACKARD MODEL 7702B)
(NSN 6625-00-464-2957)
REPORTING OF ERRORS
DEPARTMENT OF THE ARMY
11 May 1979
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.
Since the manual was not prepared in accordance with military specifications , the format has
not been structured to consider levels of maintenance.
i
Model 7702A TM 11-6625-2751-14&P
TABLE OF CONTENTS
Section Page
O INTRODUCTION 0-1 Section Page
I. GENERAL INFORMATION .......................1-1 IV. PRINCIPLES OF OPERATION............................ 4-1
1-1. Description ......................................1-1 4-1. Introduction.............................................. 4-1
1-6. Component Identification ...........1-1 4-3. Basic Circuits........................................... 4-1
1-8. Standard System Options..........1-1 4-4. Diodes................................................ 4-1
1-10. Special Options .........................1-1 4-9. Transistors ......................................... 4-1
1-12. Component Description ..................1-1 4-12. Component Circuit Description ................ 4-3
1-13. Model 7702-OlA Recorder.........1-1 4-13. Preamplifiers. ..................................... 4-3
1-16. Model 7700-02A Driver.............. 4-16. Driver Amplifier................................... 4-3
Amplifier.....................................1-3 4-26. System Power Supply ....................... 4-5
1-18. Preamplifiers, 8800 Series.........1-3 4-33. Recorder Description .............................. 4-9
1-20. Model 1069-02A Mobile Cart.....1-3 4-35. Chart Drive Components.................... 4-9
1-22. System Specifications................1-3 4-37. Drive Motor and Speed
............................................... Reduction Gears ................................4-9
II. INSTALLATION..........................................2-1 4-40. Push-button Actuated Clutch
2-1. Introduction .....................................2-1 Assemblies ..................................... 4-11
2-3. Initial Inspection .............................2-1 4-44. Chart Drive Circuits.................................. 4-11
2-4. Mechanical Inspection ...............2-1 4-47. Stylus Heat Circuits ................................. 4-12
2-6. Electrical Check ........................2-1 4-51. Marker and Timer Circuit ......................... 4-13
2-8. Claims and Repackaging ................2-1
2-9. Claims for Damage ....................2-1 V. MAINTENANCE ................................................... 5-1
2-11. Repacking for Shipment ............ 5-1. Introduction ............................................. 5-1
or Storage ..............................2-1 5-3. Test Equipment ....................................... 5-1
2-13. Installation.......................................2-1 5-5. Performance Checks .............................. 5-1
2-15. Environment...............................2-1 5-6. General .............................................. 5-1
2-19. Rack Mounting Instructions........2-1 5-8. Variable Line Voltage............................... 5-1
2-21. System in Portable Case ...........2-1 5-10. Preventive Maintenance .......................... 5-9
2-23. AC Power Requirements ...........2-1 5-12. Mechanical......................................... 5-9
2-26. Input Signal Connections...........2-2 5-16. Electrical ............................................ 5-10
2-28. Signal Input Connectors ............2-2 5-18. Cleaning ............................................. 5-10
2-30. Signal Input Cable .....................2-2 5-20. Lubrication ......................................... 5-10
2-33. Input Connector Wiring for......... 5-23. Brake and Drive Roll
Non-Guarded Preamplifiers .......2-3 Maintenance Procedures ................... 5-10
2-35. Input Connector Wiring for .............. 5-24. Brake Roll Lubrication........................ 5-10
Guarded Preamplifiers...............2-3 5-25. Brake Roll Adjustment........................ 5-11
2-37. 8805A Carrier Preamplifier.............. 5-29. Drive Roll Replacement...................... 5-12
Input Cables...............................2-4 5-36. Paper Take-Up Maintenance
2-39. Cable Assembly for use with........... Procedures ........................................5-14
Sanborn Transducers ................2-4 5-37. Paper Take-Up Adjustment ................ 5-14
2-41. Instructions for Assembling ............. 5-38. Paper Take-Up Assembly
Signal Input and Reference ....... Lubrication ..................................... 5-14
Cables........................................2-4 5-41. Stylus Adjustments and Repairs.............. 5-15
2-43. 8806A Phase Sensitive Demod- ..... 5-42. Stylus Pressure ................................. 5-15
ulator Signal Cables ..................2-4 5-44. Stylus Mechanical Stop...................... 5-16
2-47. Signal Monitor Connections ...........2-5 5-46. Stylus Mechanical Center
2-49. Remote Recorder Operation ...........2-5 (Zero).............................................. 5-16
2-51. Remote Chart Drive................... 5-48. Corrective Maintenance........................... 5-16
START-STOP control.............2-5 5-49. Disassembly of System
2-54. Remote Marker Control..............2-5 Components ................................... 5-16
2-57. Auxiliary Marker Operation.........2-5 5-56. Disassembly and Lubrication of
2-59. Initial System Check .......................2-5 Chart Drive Components.................... 5-17
2-63. To Check Recorder Drive .......... 5-59. Chart Drive Lubricants........................ 5-17
Functions................................2-5 5-61. Shaft Disassembly and
2-64. To Check Recorder Marker............. Lubrication .....................................5-18
and Timer Functions .................2-5 5-63. Shaft A Servicing ............................... 5-18
............................................... 5-64. Shaft B Servicing ............................... 5-18
III. OPERATION..............................................3-1 5-66. Shaft C Servicing ............................... 5-18
3-1. Introduction .....................................3-1 5-67. Shaft D Servicing ............................... 5-18
3-3. Controls and Connectors.................3-1 5-69. Shaft E Servicing 5-20
3-5. Operating Procedures ....................3-1 5-70. Shaft F Servicing .................................... 5-20
ii
TM 11-6625-2751-14&P
Model 7702A
TABLE OF CONTENTS (Cont.)
Section ..................................................Page Section ...................................................Page
V. MAINTENANCE (Cont.) ............................. V. MAINTENANCE (Cont.)
5-72. Drive Motor Sprocket and................. 5-85. Troubleshooting ................................5-24
Chain Lubrication ........................5-20 5-87. Electrical Performance Check............5-24
5-73. Gear Lubrication ..............................5-20 5-89. Mechanical Problems.........................5-24
5-75. Results of Incorrect Lubrica-............. 5-92. Etched Circuit Board Repair...............5-24
tion Procedure ............................. 5-20 5-95. Component Replacement..................5-24
5-77. Galvanometer Assembly .................5-20 VI. UPDATING SUPPLIES. ................................6-1
5-80. Galvanometer Magnet
Replacement.............................5-20 VII. MANUAL CHANGES.....................................7-1
5-82. Galvanometer Insert
Replacement................................5-20
LIST OF ILLUSTRATIONS
Figure ..................................................Page Figure ...................................................Page
1-1. Model 7702A Recording System and......... 4-9. Unregulated ± 18 V Supply ..........................4-6
Option 01 ..........................................1-0 4-10. Unregulated ± 18 V Power Distribution..........4-7
1-2. Model 7702-0lA Recorder ..........................1-2 4-11. Regulated ± 12 V Supply...............................4-7
1-3. Model 7700-02A Driver Amplifier................1-2 4-12. Regulated ± 12 V Power Distribution.............4-8
1-4. 8800 Series Preamplifier (8801Ashown)....1-2 4-13. 440 Hz Plug-In Oscillator Block Diagram
1-5. Model 1069-02A Mobile Cart .....................1-3 With Associated Circuits ...............................4-8
1-6. 7702A System Power Supply. ...................1-3 4-14. 2400 Hz Plug-In Oscillator Block
.................................................. Diagram ...................................................4-9
2-1. Slide Kit - 01060-60310 .............................2-2 4-15. Chart Drive Motor and Speed
2-2. Portable Case ............................................2-2 Reduction Gears............................................4-10
2-3. 10G3-34FW Connector ..............................2-2 4-16. First Speed Reduction Assembly
2-4. Cable Preparation.......................................2-3 Operation ...................................................4-11
2-5. Input Connector Wiring, Non-Guarded.......2-3 4-17. Chart Drive Circuit ........................................4-12
2-6. Input Connector Wiring, Guarded. .............2-4 4-18. Stylus Heat Control Circuit ............................4-13
2-7. Y-Cable Sanborn No. 5060-4602 ...............2-4 4-19. Marker and Timer Control Circuitry ...............4-14
2-8. Remote Run Circuit Diagram .....................2-5
2-9. Remote Marker Circuit Diagram.................2-5 5-1. Recorder Platen Writing Edge.......................5-8
2-10. System Controls.........................................2-6 5-2. Stylus Adjustment Screws and Limits............5-9
.................................................. 5-3. Brake Roll Adjusting Screw Location.............5-11
3-1. Typical 2-Channel Recording ....................3-1 5-4. Brake Roll Removal.......................................5-11
3-2. Front Panel Controls ..................................3-2 5-5. Bearing Retainer and Gears .........................5-12
3-3. Rear Panel Controls .................................3-3 5-6. Paper Table Removal....................................5-13
3-4. Permapaper Loading Procedures ..............3-4 5-7. Paper Take-Up Adjustment...........................5-14
3-5. System Operating Procedures .................3-6 5-8. Calibrating and Measuring Stylus
3-6. Remote System Operation .........................3-7 Pressure ............................................5-15
.................................................. 5-9. Stylus Pressure Adjustment ..........................5-16
.................................................. 5-10. Heated Stylus Part No. 398............................5-17
4-1. Model 7702A System Block Diagram.........4-1 5-11. Chart Drive Shafts .......................................5-19
4-2. Basic Diode Circuits ..................................4-2 5-12. Shaft A Lubrication Procedures..................... 5-21
4-3. Transistor Operation ................................4-2 5-13. Clutch Sleeve Clearance...............................5-23
4-4. Signal Distribution Diagram .......................4-4 5-14. Shaft C Inspection.........................................5-23
4-5. Model 7700-02A Driver Amplifier................ 5-15. Excessive Wear in Clutch Assembly.............5-23
Block Diagram .................................4-4 5-16. Checking Galvanometer Sensitivity...............5-24
4-6. Feedback Circuit - Simplified Schematic....4-5 5-17. (a) Troubleshooting Chart
4-7. Galvanometer Frequency Response and... Problems in One Channel ............................5-27
Transient Response..........................4-5 (b) Troubleshooting Chart
4-8. 7702A System Frequency Response .......4-6 Problems in Both Channels ....................................5-28
iii
TM 11-6625-2751-14&P
Model 7702A
LIST OF ILLUSTRATIONS (Cont.)
Illustrated Parts Breakdown
Figure ..................................................Page Figure ...................................................Page
1. Two-Channel Thermal Recording Sub-...... 13. Power Supply Assembly, Top View
System (Model 7702A) ................... 5 (07702-60030) ...................................27
2. Two-Channel Thermal Recorder................ 14. Power Supply Assembly, Bottom View
115/230V, 60Hz (Model 7702-01A).. 7 (07702-60030)....................................29
3. Driver Amplifier Assembly.......................... 15. Regulator Card and Bracket Assembly
(Model 7700-02A) ............................ 9 (868-500A-C6)...................................31
4. Printed Circuit Board Assembly.................. 16. Diode Board Assembly (07702-60070).........33
(07700-62010)............................................11 17. Oscillator Card Assembly, 2400 Hz
5. Amplifier Housing Assembly ....................13 (868-500A-C13).................................35
6. Galvanometer Assembly Complete............ 18. Oscillator Card Assembly, 440 Hz
(320-200-Cl0)....................................15 (868-500A-C14)............................37
7. Front Panel, Door and Paper Take-Up....... 19. Timer Assembly (14002S - 14002T -
Assembly (07702-60220) .......................... 17 14002R- 14002V)...............................39
8. Ten-Button Push Switch (3101-1001)........19 20. MM/Min Drive Motor Kit - 60:1
9. Paper Drive Assembly (table, brake........... (07702-60110) (07702-60220)...........39
and associated parts)....................... 21 21. Mobile Cart (1069-02A) ...............................41
10. Paper Drive Assembly (gear train and........ 22. Portable Case (7702-14A).............................43
associated parts) ..................................... 23 23A.7702-01A Recorder Schematic.....................47
11. Table, Drive Roll and Brake Assembly....... 25 23B.Model 7702A Power Supply Plug-In
12. Clutch Actuator Assembly (07702-60100).. 25 Assemblies, Schematic Diagram.......49
LIST OF TABLES
Table ..................................................Page Table ...................................................Page
1-1. Model 7702-01lA Specifications ................1-4 5-1.Recommended Test Equipment ...................5-1
1-2. Model 7700-02A Specifications .................1-5 5-2.Performance Checks ....................................5-2
1-3. 8800 Series Preamplifiers .........................1-5 5-3.Recorder Minor Repairs and
1-4. System Specifications................................1-6 Adjustments...................................................5-5
1-5. System Accessories...................................1-7 5-4.Timing Calibration..........................................5-12
.................................................. 5-5.Lubricants....................................................5-17
4-1. Speed Reduction Ratios ............................4-11
4-2. Timer Assembly Part Numbers ................4-15
APPENDIXES
A. ILLUSTRATED PARTS BREAKDOWN.........................................................................................................A-1
B. REFERENCES ...............................................................................................................................................B-1
C. COMPONENTS OF END ITEM LIST (not applicable)
D. ADDITIONAL AUTHDRIZATION LIST (not applicable)
E. MAINTENANCE ALIOCATION ......................................................................................................................E-1
F. EXPENDABLE SUPPLIES AND MATERIALS LIST (not applicable)
G. REPAIR PARTS AND SPECIAL TOOLS LISTS (PART NUMBER - NATIONAL STOCK
NUMBER CROSS REFERENCE INDEX) ...............................................................................................G-1
iv
Model 7702A
TM 11-6625-2751-14&P
Figure 1-1. Model 7702A Recording System and Option 01
0-0
SECTION O.
INTRODUCTION
0-1. SCOPE.
This manual describes Oscillograph Recorder RO460(V)1/U and provides instructions for operation and
maintenance. Throughout this manual, the RO-460(V)
1/U is referred to as Hewlett-Packard Model 7702B.
Refer to Section VI for differences between the 7702A
and 7702B.
0-2. INDEXES OF PUBLICATIONS.
a. DA Pam 310-4. Refer to the latest issue of DA
Pam 310-4 to determine whether there are new editions,
changes, or additional publications pertaining to the
equipment.
b. DA Pam 310-7. Refer to DA Pam 310-7 to
determine whether there are modification work orders
(MWO’s) pertaining to the equipment.
0-3. FORMS AND RECORDS.
a. Reports of Maintenance and Unsatisfactory
Equipment. Maintenance forms, records, and reports
which are to be used by maintenance personnel at all
maintenance levels are listed in and prescribed by TM
38-750.
b. Report of Packaging and Handling
Deficiencies. Fill out and forward DD Form 6 (Pack aging
Improvement Report) as prescribed in AR 70058/NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A
and DSAR 4145.8.
TM 11-6625-2751-14&P
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. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR).
EIR’s will be prepared using Standard Form SF 368,
Quality Deficiency Report. Instructions for preparing
EIR’s are provided in TM 38-750, The Army Maintenance Management System. EIR’s should be mailed
direct to Commander, US Army Communications and
Electronics Materiel Readiness Command, ATTN:
DRSEL-ME-MQ, Fort Monmouth, NJ 07703. A reply will
be furnished directly to you.
0-5. ADMINISTRATIVE STORAGE.
Administrative storage of equipm ent issued to and used
by Army activities shall be in accordance with paragr aph
2-11.
0-6. DESTRUCTION OF ARMY ELECRONICS MATERIEL.
Destruction of Army electronics materiel to prevent
enemy use shall be in accordance with TM 750-244-2.
0-1
SECTION I.
GENERAL INFORMATION
1-1. DESCRIPTION.
1-2. The Sanborn Model 7702A is a two-channel
thermal writing recording system, mounted in a mobile
cart, that has excellent versatility through the use of all
solid-state 8800 Series interchangeable pre- amplifiers.
Any two of the 8800 Preamplifiers (see Table 1-3) may
be used with the Model 7702A, permitting a broad range
of measurements. ’Possible applications include high
sensitivity AC and DC measurements, carrier excited
transducer monitoring, rec ording of phase and amplitude
in servo systems, and obtaining permanent records of
AC levels having a wide dynamic range directly in dB on
a linear scale. Complete operating and service
instructions for eac h of the 8800 Ser ies Pream plif iers are
contained in separate manuals.
TM 11-6625-2751-14&P
e. Option 11: Eight-speed recorder for 60 Hz power
line. (Adds four mm/min recorder speeds by means of a
60:1 speed reduction.)
f. Option 12: Eight-speed recorder for 50 Hz power
line. (Adds four mm/min recorder speeds by means of a
60:1 speed reduction.)
g. Option 13: One minute timer for 60 Hz power
line. Provides one per minute timing marks on chart. For
use with Option 11.
h. Option 14: One minute timer for 50 Hz power
line. Provides one per minute timing marks on chart.
Used with Option 12.
i. Option 15: Auxiliary marker. Records between
channels 1 and 2 on chart paper; actuated by external
contact closure.
1-10. Special Options.
1-3. The 7702A is also available in a portable carrying
case with a protective cover over the front panel, or the
recorder may be rack mounted.
1-4. Input signals to the 7702A System are connected to the signal input panel located on the rear of the
recorder. The input connector contains a guard shield for
high common-mode rejection. Output signals are
available at the signal panel for connection to an
oscilloscope or magnetic recorder.
1-5. Four chart speeds for industrial or medical
applications are selected by front panel pushbuttons.
Eight chart speeds, pushbutton selected, are optional.
The recorder start-stop func tion is controlled either from
the front panel or from a remote location.
1-6. Component Identification.
1-7. This Sanborn System consists of the following
major components:
a. Model 7702-OlA Recorder Assembly, including
power supply for preamplifiers and driver amplifiers.
b. Model 7700-02A Driver Amplifiers (2).
c. Model 1069A-02A Mobile Cart.
d. 8800 Series Preamplifiers, as ordered.
1-8. Standard System Options.
1-9. The basic System, Model 7702A, is available
with the following standard system options:
a. Option 01: 7702A System less mobile cart.
Slide kit 01060-60310 is included for rack mounting.
b. Option 02: The 7702A System less mobile
cart, mounted in portable case.
c. Option 08: For 50 Hz power line.
d. Option 10: Recorder with medical speeds
(2. 5, 5, 25, and 50 mm/sec).
1-11. When contractual requirements require special
modifications to the standard Sanborn 7702A System,
complete data on the difference between the modified
and standard system is covered in Section VII of this
manual.
The contents of this manual apply directly
to instruments with Production Change
Order (PCO) numbers up to 17-15637. Refer
to Section VII for other PCO numbers
1-12. COMPONENT DESCRIPTION.
1-13. Model 7702-01A Recorder.
1-14. The 7702-0lA (Figure 1-2 shown with preamp
lifiers installed) is a two-channel, four or eight-speed
thermal writing recorder, with provisions f or m ounting two
8800 Series Preamplifiers. The recorder is mounted
horizontally in the 7702A Mobile Cart, or vertically in the
portable case or rack mount. The paper take-up
assembly located on the left end of the recorder stores
the chart paper on a take-up spool that is easily
removed. Recorder charac teristics are given in Table 1-
1.
1-15. The power supply (Figure 1-6) provides oper-
ating power for the 7702-OlA Recorder, 8800 Series
Preamplifiers, and two 7700-02A Driver Amplifiers. The
mm/sec timer assembly 14002S and the optional
mm/min timer assembly 14002R plug into the power
supply. Also mounted on the rear of the power supply are
three plug-in circuit boards; (1) Regulator Card 868500A-C6 which furnishes regulated +12 and -12 volts to
the preamplifiers, (2) Oscillator Plug-in 868-500A-C13
which provides a 2400 Hz transducer excitation voltage
for use with the 8805A Carrier Pre- amplifier, and (3)
Oscillator Plug-in 868-500A-C14 which provides a 440
Hz chopper excitation voltage for Model 8803A High Gain
Preamplifier.
1-1
TM 11-6625-2751-14&P
Figure 1-2. Model 77-01A Recorder
Figure 1-3. Model 7700-02A Driver Amplifier Figure 1-4. 8800 Series Preamplifier (8801A Shown)
1-2
1-16. Model 7700-02A Driver Amplifier.
1-17. One plug-in driver amplifier (Figure 1-3) is
provided for each recording galvanometer. The combination of driver amplifier and galvanometer simulate
the characteristics of a galvanometer at 71% of critical
damping, by negative velocity-voltage feed- back from
the galvanometer in conjunction with a compensation
circuit in the driver amplifier. Driver Amplifier
specifications are listed in Table 1-2. 1-18.
Preamplifiers, 8800 Series.
1-19. Any of the solid-state high performance preamplifiers (Figure 1-4) for medical or industrial
applications may be installed in the recorder. Preamplifiers may be interchanged easily from the front
panel of the recorder by removing two panel mounting
screws. Preamplif iers c ontain built-in voltage cali- br ation
sources.
1-20. Model 1069-02A Mobile Cart.
1-21. The ruggedly constructed all-metal mobile cart
(Figure 1-5) is an ideal unit for many recording
applications. Metal bar handles mounted on both ends of
the cart and large diameter rubber wheels permit the
system to be moved from one location to another with
minimum effort. The line power cord, which is
permanently attached to the cart, is conveniently stored
behind the rear panel. Two AC accessory out- lets are
provided on the rear panel. A 5" high panel located on
the top of the cart and two 7" panels loc ate on the front
of the cart may be used to m ount signal panels or other
instrumentation. 1-22. System Specifications.
TM 11-6625-2751-14&P
Figure 1-5. Model 1069-02A Mobile Cart
1-23. The power, weight and dimensions for the Model
7702A are listed in Table 1-4.
1-24. Accessories provided with the System (or
available on order) are listed in Table 1-5.
Figure 1-6. 7702A System Power Supply
Figure 1-6. 7702A System Power Supply
1-3
TM 11-6625-2751-14&P
Table 1-1. Model 7702-01A Specifications
RECORDER
CHART SPEEDS:1, 5, 20, and 100 mm/sec are standard; four additional s peeds : 1, 5, 20, 100, mm/min, available
as Option 11 (eight speeds total). Medical speeds of 2. 5, 5, 25, and 50 mm/ sec available instead of standard
speeds as Option 10. Options 10 and 11 may be combined for a total of eight medical speeds. Non-standard
speeds available on special order. Speed regulation 1% at specified power line frequency.
CHART PAPER: 2-channel Permapaper( Sanborn No. 651-52. Paper width 5" (127 mm). Each recording
channel 50 mm wide, with amplitude lines spaced 1 mm apart. Timing lines also have 1 mm spacing.
STYLUS: Stylus heat electrically controlled by speed selector and also adjustable by front panel control. Analog
Stylus, Sanborn No. 398; Marker/Timer Stylus, Sanborn No. 411-10.
STYLUS HYSTERISIS: Recording affected by previous signals by less than 0O. 1 divisions. DAMPING:
Galvanometer with velocity-voltage feedback in combination with drive circuit simulates a 71% critically
damped galvanometer.
MARKER: Marker on right side (lower edge) of chart is standard; center margin marker optional; amplitude of
marker approximately 1. 5 mm. Marker is operated by front panel switch or by external contact closure.
TIMER: With TIMER pushbutton depressed, marker pulse occurs on right side of chart every second (standard) or
every minute (see standard option, Paragraph 1-8). Marker operation over-rides
timer signal.
COOLING: Mounting case vented top and bottom for convection cooling. For rack mounting, temperature inside rack
should not exceed 40’C.
TERMINALS: Signal input, signal monitor, remote chart drive start-stop, and servo reference input
located on rear.
FRONT PANEL CONTROLS: Individual STYLUS heat adjustments; individual galvanometer DAMPING
screwdriver adjust; pushbutton TIMER, MARK and POWER switches; pushbutton SPEED
selector switches.
POWER SUPPLY
OUTPUT:
Regulated +12 volts at 500 milliamperes maximum, each polarity.
Unregulated ±18 volts at 1/2 ampere maximum, each polarity, less ±12V load current.
Regulation of ±12 volt output a) with 20% change in line voltage 1/o maximum.
b) with change in load, 0 to full load 2% maximum.
c) with change in temperature 3 mV/C' maximum.
Ripple on ±12 V output at full load 10 millivolts maximum, peak-to-peak.
Dynamic output impedance of +12V output: 1/2 ohm, DC to 10 kHz.
OSCILLATORS:
440 Hz Oscillator, 868-500-C14: Frequency Stability: 440 Hz ± 5% maximum. Output: Floating
at 14 volts peak-to-peak at 1/2 watt. Amplitude stability +2% of constant load.
2400 Hz Oscillator, 868-500A-C13: Frequency Stability: 2400 Hz + 2% maximum. Output:
10 volts rms ±5% at 50 milliwatts maximum. Grounded center tap.
1-4
TM 11-6625-2751-14&P
Table 1-2. Model 7700-02A Specifications
DRIVER AMPLIFIER
FREQUENCY RESPONSE: DC to less than 3 dB down at 125 Hz for chart deflection of 10 divisions pp.
Damping set for 4% overshoot with a 10 division pp square wave.
SENSITIVITY: ±2. 5 volts nominal for full recording chart width deflection.
NOISE: Less than 0. 1 division pp with zero signal input.
RESPONSE TIME: Less than 5 msec, 10% to 90% for a 10 division square wave with damping set for 4%
overshoot.
DRIVER INPUT IMPEDANCE: (preamplifier output loading) 5K ohms, ±5%, single-ended, with signal
ground isolated from chassis ground.
LINEARITY:
Method 1: After setting mechanical zero of stylus within 0o. 1 division of chart center and calibrating for zero error at center scale and +20 divisions, error is less then ±0. 25 divisions at any point
on printed coordinates.
Method 2: After setting mechanical zero of stylus within +1 division of chart center and calibrating
for zero error at lower and upper ends of printed coordinates, error is less than t0. 5 division at
any point on the scale.
GAIN STABILITY (after one hour warmup): Temperature: Less than 0. 25%/10'C, 20° to 40°C.
Line Voltage: 0. 5%, 103 to 127 volts.
ZERO DRIFT (driver amplifier input shorted and after one hour warmup): Temperature: Less then
0.25 div/10°C, 20° to 40°C. Line Voltage: 0.1 div, 103 to 127 volts. Paper Drift: Less than
0.25 div.
LIMITING: Electrical limiting in drive circuit at approximately 125% of full scale. Stylus is mechani-
cally limited by spring stops.
Table 1-3. 8800 Series Preamplifiers
Preamplifier Description Sensitivity
8801A Low Gain DC Preamplifier 5 mV/div
8802A Medium Gain DC Preamplifier 1 mV/div
8803A High Gain DC Preamplifier 1 µV/div
8805A Carrier Preamplifier (with calibrated CAL factor) 10 µV/div
8806B Phase Sensitive Demodulator 0. 5 mV rms/div
8807A AC-DC Converter 1 mV rms/div (at x20
scale expansion)
8808A Log-Level Preamplifier 100 µV rms
8809A Special Purpose DC 20 mV/div
NOTE: All preamplifiers except 8806B and 8808A feature calibrated zero suppression.
1-5
TM 11-6625-2751-14&P
Table 1-4. System Specifications
POWER: 115/230 volts ± 10%, 60Hz, approximately 200 watts. 115/230 volts ±10%, a50 Hz, specify Option 08.
WEIGHT: 130 lb. (59kg), includes 1069-02A Mobile Cart and two preamplifiers.
DIMENSIONS: (see illustrations below)
1-6
TM 11-6625-2751-14&P
Table 1-5. System Accessories
Qty. Description Number
2 Signal Input Connector 10G3-34FW
2 Signal Output Connector 10B9-5MW
1 Remote Run Connector 10A5-3MW
1 Remote Run Connector Cable Clamp 10OA5-lFWA
1 Remote Marker Plug 10G2-22MW
1 Power Cord 3-wire 10G3-42MFW
1 Adapter, 3-wire to 2-wire 10G3-11MFW
2 Fuse 0.5 Amp Slo Blo (F2, F3) 26B-4
1 Fuse 0.8 Amp Slo Blo (Fl 220V) 26B-6
1 Screwdriver 37A-10A
2 Record Spool 94-104P1
1 Spline Wrench 100-600-C5
2 Galvanometer Stylus 398
1 Roll, Permapaper 651-52
1 Stylus Pressure Tester 14015A
1-7
SECTION II.
INSTALLATION
TM 11-6625-2751-14&P
2-1. INTRODUCTION.
2-2. This section contains information on unpacking, inspection, repacking, and installation.
2-3. INITIAL INSPECTION.
2-4. Mechanical Inspection.
2-5. If external damage to the shipping carton is
evident, ask the carrier’s agent to be present when the
System is unpacked. Check the System for external
damage such as broken controls or connectors, and
dents or scratches on the panel surface. If damage is
found, refer to Paragraph 2-8 for recommended claim
procedure and repacking information. If the shipping
carton is not damaged, check the cushioning material
and note any signs of severe stress as an indication of
rough handling in transit. Retain the packaging material
for possible future use.
2-6. Electrical Check.
2-7. Check the electric al performance of the Sys- tem
as soon as possible after rec eipt; see Section V for the
recommended performance checks. The checks will
verify that the System is operating within the
specifications listed in Table 1-1. This check is a good
test procedure for incom ing quality control inspection and
for an operational check after repairs or adjustments
have been made.
2-8. CLAIMS AND REPACKAGING.
2-9. Claims for Damage.
2-10. If physical damage is evident or if the System
components do not meet specifications when received,
notify the carrier and the nearest Hewlett-Packard
Sales/Service Office (see list in back of manual). The
Sales/Service Office will arrange for repair or
replacement of the unit(s) without waiting for settlem ent
of the claim against the carrier.
2-11. Repacking for Shipment or Storage.
2-12. If the instrument is to be shipped to a HewlettPackard Sales/Service Office, attach a tag showing
owner and address, instrument model and serial number,
and the repair required. The original ship- ping carton
and packaging material, with the exc eption of accor dionpleated pads, may be reusable. The Hewlett-Packard
Sales/Service Office will also pro- vide information and
recommendations on materials to be used if the original
packaging material is not available or not reusable.
Materials should include, (1) a double-walled carton
(check with a freight carrier for test s tr ength requir ed), ( 2)
heavy paper or sheets of cardboard to protect all
instrument surfaces ; use extra m aterial ar ound projec ting
parts of the instrument, (3) at least four inches of tightlypacked shock-absorbing material surrounding the
instrument. Close the package securely with heavy paper
tape.
2-13. INSTALLATION.
2-14. The 7702A System is ready for use after removal from the packing case. No packing materials are
contained in the recorder section. T he system is shipped
without Permapaper mounted in the recorder; see paper
loading instructions in Section III.
2-15. Environment.
2-16. System location should be reasonably free from
vibration, dust, corrosive or explosive vapors or gases,
extremes of tem perature, humidity, etc. The floor should
be level and must supply support for all four wheels of
the System. For a cabinet mounted installation, allow
sufficient room at the f ront for operation with any part of
the System extended forward, and at the rear for
servicing with access door open.
2-17. The 7702A System requires no additional cooling. For rack mounting (7702A, Option 01), the tem per-
ature inside the rack cabinet should not exceed 40°C.
2-18. Check that the power line voltage, voltage regulation, power capacity, frequency, and frequency
stability are suitable for the requirements of the Sys- tem.
The time-axis accuracy of the recording will be directly
dependent upon the frequency stability of the power line.
2-19. Rack Mounting Instructions.
2-20. Model 7702A, Option 01, consists of the Model
7702-0lA Recorder, with Slide Kit 01060-60310, for
mounting in a cabinet. To install the recor der, attach the
slides to the side rails of the c abinet. Figure 2-1 shows
the location of the mounting holes for the slide kit. Slide
the recorder into the side rails and fasten the recorder in
place with panel screws.
2-21. System in Portable Case.
2-22. Model 7702A, Option 02, consists of the 7700OlA Recorder mounted in a portable transit case 770214A, shown in Figure 2-2. Two side handles are used f or
carrying the case. A removable metal c over protects the
recorder front panel when being transported. Signal input
and power cables are connected to the s ystem through
an open- ing in the rear of the case.
2-23. AC Power Requirements.
2-24. The Model 7702A may be operated from an ac
source of 155 or 230 volts (+10%), 60 Hz. Model 7702A,
Option 08, operates on 115 or 230 volts (+10%), 50 Hz.
With the instr ument power cord disconnected, move the
slide switch located on the rear panel (see Figure 3-3)
until the desired voltage numbers (115 or 230) are
visible. A narrow blade screwdriver may be used to
operate the switch. Fuse F1 should be 1.5 amp slowblow for 115 volt operation, or 0.8 amp slow-blow for 230
volt operation.
2-1
TM 11-6625-2751-14&P
Figure 2-2. Portable Case
Figure 2-1. Slide Kit - 01060-60310
2-25. Three-Conductor Power Cable. To protect
operating personnel, the National Electrical
Manufacturers’ Association (NEMA) recommends that
the instrument and cabinet be grounded. The Model
7702A is supplied with a three-conductor power cable
which, when plugged into an appropriate receptacle,
grounds the instrument to the power line ground. The
round pin on the power cable is the ground c onnection.
To retain this protection feature when operating the
instrument from a two-contact outlet, use the 10G311lMFW three-conductor to two- conductor adapter
(supplied as an accessory with the instrument) and
connect the green wire to the outlet box.
2-26. Input Signal Connections.
2-27. The 8800 Preamplifier signal input circuits may
be divided into two types, guarded and non- guarded.
Preamplifiers having a guard shield terminal (8803A,
8806B, 8807A) feature a high comm on- mode rejection
ratio. To obtain the high rejection ratio, the signal input
cable must contain a guard shield. Non-guarded
preamplifiers (8801A, 8802A, 8805A, 8808A, 8809AY do
not require a guard shield in the signal input cable.
Additional information on input signal connections is
contained in the preamplifier instruction manuals.
Figure 2-3. 10G3-34FW Connector
2-28. Signal Input Connectors.
2-29. Two signal input connectors, 10G3-34FW(see
Figure 2-3), are supplied as access ories with the system.
The connectors plug into the signal input jac k s J 1 and J2
on the rear of the recorder. J1 signals (channel 1) are
internally cabled to the left pre- amplifier (viewed from the
front of the recorder) and r ecorded on the upper channel
of the chart paper. J2 input signals are cabled to the right
preamplifier, and are recorded on the lower channel of
the chart
paper.
2-30. Signal Input Cable.
2-31. Two conductor shielded cable 3/16" O.D., with
single or doubled braided shield is required for connecting the signal source to the input connectors. See
Figure 2-4 for cable preparation information.
2-2
TM 11-6625-2751-14&P
NOTE
Single conductor cable can be used
with the 8808A and 8809A Preamplifiers, which have single-ended input
circuits. Connect the cable center
conductor to pin A, and the shield to
pin B.
Figure 2-6. Input Connector Wiring, Guarded
2-32. Preamplifiers which have a guard shield input
terminal use double shielded cable for a fully guarded
input circuit. The inner shield connects to the common mode potential of the signal source to reduce
capacitive and resistive currents between the signal
conductors and ground. The outer shield is grounded,
to prevent capacitive coupling of the common mode
potential on the inner shield into other circuitry. In
many cases, the second (outer) shield may be omitted with no deterioration in performance.
2-33. Input Connector Wiring for Non-Guarded
Preamplifiers.
2-34. The following instructions are for wiring the
input connector using either single or double shielded
cable.
a. Loosen the 10G3-34FW connector cable clamp
screws.
b. Slide the dressed end of the cable into the
cable clamp and through the connector shell.
c. Remove and store the guard shield extension.
d. Solder the cable center conductors to connector pins A and B. See Figure 2-5.
e. Solder the cable shield(s) to pin C.
f. Press the connector block carefully into the
connector shell, allowing the cable to pass through
the connector clamp.
g. Insert the retaining ring.
h. Tighten the cable clamp screws.
Figure 2-5. Input Connector Wiring, Non-Guarded
2-35. Input Connector Wiring for Guarded
Preamplifiers.
2-36. The following instructions are for wiring the
input connectors using either single or double shielded
cable.
a. Loosen the 10G3-34FW connector cable clamp
screws.
b. Slide the dressed end of the cable into the
cable clamp and through the connector shell.
c. Slide the guard shield extension down over the
cable shield(s) and onto the guard socket.
d. Solder the cable center conductors to pins A
and B. See Figure 2-6.
e. For single shield cable, solder the cable shield
to the guard shield extension.
f. For double shield cable solder the inner
(guard) shield to the guard shield extension, and solder the outer shield to pin C. Check that shields are
not shorted to each other or to the connector shell.
g. Press the connector block carefully into the
connector shell, allowing the cable to pass through
the cable clamp.
h. Insert the retaining ring.
i. Tighten the cable clamp screws.
2-3
Figure 2-6. Input Connector Wiring, Guarded
2-37. 8805A CARRIER PREAMPLIFIER INPUT
CABLES.
2-38. Carrier preamplifier operation requires both a
non-guarded signal input cable and a carrier refer- ence
cable, connected between the strain gage or transducer
and the 7702A System. A cable assembly for use with
Sanborn transducers is shown in Figure 2-7. Cables for
other applications are assembled
following the instructions in Paragraph 2-41.
TM 11-6625-2751-14&P
(2) Connect the cable to jack J1 (for channel 1)
or jack J2 (for channel 2), located on the rear panel of
the recorder.
b. Carrier Reference Cable. (1) Connect a twoconductor shielded cable to the 10B9-5MW connector,
supplied as an accessory with the system. Solder the two
cable conductors to pins A and B, cable shield to pin E.
(2) Connect the cable to jack J21 (for channel 1)
or jack J22 (for channel 2) located on the rear panel of
the recorder.
2-43. 8806B PHASE SENSITIVE DEMODULATOR
SIGNAL CABLES.
2-44. Demodulator preamplifier operation requires both
a signal input cable and a servo reference cable.
Construction of the cables is described below.
2-45. Construct the two-conductor signal input cable
with a guard shield (see Paragraph 2-
35)
if a high
common-mode rejection is desired. If high commonmode rejection is not required, the input cable is wired
with an unguarded, single-shield cable (see Paragr aph 2-
33). Connect the signal input cable to J1 (channel 1) or
J2 (channel 2).
2-46. Construct the servo reference cable using twoconductor shielded cable and the 10B9-5MW con- nector
supplied as an accessory with the system. Normal
connection uses a single-shielded cable, in a nonguarded circuit. Solder the "+" servo ref erence signal to
pin K, and the "-" servo reference to pin F. Connect the
servo reference cable to J21 (c hannel 1) or J22 (channel
2), located on the rear panel of the 7702A Recorder.
2-39. Cable Assembly for use with Sanborn
Transducers.
2-40. Use the cable assembly no. 5060-4602 (Figure
2-7) to connect Sanborn Series 267, 268 and 270 Series
Transducers to the 7702A System. T his Y-cable contains
both a signal input cable and a carrier reference cable.
2-41. Instructions for Assembling Signal Input
and Reference Cables.
2-42. Signal input and carrier reference cables for
carrier preamplifier applications described in the
instruction manual IM-8805A-1 are assembled as follows:
a. Signal Input Cable.
(1) Connect a two-conductor shielded cable to the 10G334FW connector, supplied as an accessory with the
system. Solder the two cable conductors to pins A and B,
cable shield to pin C (see Paragraph 2-33).
2-4
2-47. SIGNAL MONITOR CONNECTIONS.
2-48. The preamplifier single-ended output s ignals are
available at J21 (channel 1) and J22 (channel 2), located
on the rear panel of the recorder. Signal output is pin D,
signal common is pin H. For 8803A High Gain
Preamplifier, signal out is pin A, signal com mon is pin B.
The 10B9-5MW mating connectors are supplied as
accessories with the system.
2-49. REMOTE RECORDER OPERATION.
2-50. The 7702A Recorder chart drive ST ART- STOP
function and the MARKER function can be con- trolled
from a rem ote location. The circuits required ar e shown
in Figures 2-8 and 2-9.
2-51. Remote Chart Drive START-STOP Control.
2-52. Construct the circuit shown in Figure 2-8.
The 10A5-3MW remote run connector and the 10A5lFWA cable c lamp are supplied as accessories with the
system. Any length of four conductor cable may be used.
The remote run circuit plugs into the J13 jac k on the rear
panel of the recorder.
Figure 2-8. Remote Run Circuit Diagram
2-53. To operate the recorder using the REMOTE
RUN circuit, switch the LOCAL-REMOTE switch S3
located on the rear panel of the recorder to the
REMOTE position and press the desired speed pushbutton on the recorder front panel. Operate the
remote STANDBY-RUN switch to control chart drive.
2-54. Remote Marker Control.
2-55. The marker may be operated from a remote
location or from the recorder front panel. To operate the marker from a remote location, construct
the circuit shown in Figure 2-9. The connector
10G2-22MW is supplied as an accessory with the
system. Any length of cable may be used.
2-56. The Remote marker circuit plugs into the J15
jack on the rear panel of the recorder.
2-57. Auxiliary Marker Operation.
2-58. To operate the auxiliary marker, available
as 7702A Option 15, construct a switch circuit as
shown in Figure 2-9. Plug the switch into the auxiliary marker Jack J14, located on the rear panel of
the recorder.
TM 11-6625-2751-14&P
Figure 2-9. Remote Marker Circuit Diagram
2-59. INITIAL SYSTEM CHECK.
2-60. The following procedures are designed to check
the recorder drive, marker, timer, and re- mote control
functions. To check the operation of the preamplifiers,
refer to the instruction manual for the 8800 Series
preamplifiers installed in the system.
2-61. Review the installation process, checking the
cables and connectors. Tighten all connections. Check
that the S3 power line switch (see Figure 3-3) indicates
the correct voltage. The recording system may be
damaged if the switch is set to the incorrect voltage
range.
2-62. Install a roll of Permapaper in the recorder,
following the instructions in Figure 3-4.
2-63. To Check Recorder Drive Functions.
a. Press the POWER pushbutton. The panel
indicator lamp will light.
b. Press the MM/SEC pushbutton.
c. Press each of the four speed-pushbuttons.
Check for proper paper travel at each speed selected. If
recorder is equipped with mm /min speeds, Option 11 or
Option 12, press MM/MIN pushbutton. Press each of the
four speed-pushbuttons, check ing for proper paper travel
at each speed selected.
d. Adjust the stylus HEAT controls for a dense,
well-defined baseline.
2-64. To Check Recorder Marker and Timer
Functions.
a. Press the MARKER pushbutton. A mark will be
recorded on the lower edge of the chart. To check
remote marker operation, connect the circuit shown in
Figure 2-9 to J15.
b. Press MM/SEC and TIMER pushbuttons. A
one per second timing mark will be recorded on the lower
edge of the chart. Press TIMER again to re- lease
pushbutton. If system is equipped with mm/min timer,
Option 13 or 14, press MM/MIN and T I MER pushbuttons .
A one per minute timing mark will be recorded on the
chart.
2-5
TM 11-6625-2751-14&P
Figure 2-10. System Controls
2-6
SECTION III.
OPERATION
3-1. INTRODUCTION.
3-2. The basic function of the 7702A System is to
produce graphic tracings on two-channel thermal sensitive Permapaper, using the heated stylus recording
technique. Input signals are amplified by the 8800 Series
signal conditioning preamplifiers, and displayed on 50
mm-wide channels on the chart paper. Preamplifiers
contain amplitude calibration standards which can be
recorded on the chart paper when desired. The chart
paper time scale unit is adjus table in fixed steps by the
setting of the pushbutton chart speed controls. Standar d
recorder speeds provide time scale calibration ranging
from 1 m m/sec to 100 mm/sec. W ith Option 11 (60 Hz)
or Option 12 (50 Hz), four chart speeds are added which
provide time scale calibration from 1 mm/min to 100 mm/
min.
TM 11-6625-2751-14&P
3-3. CONTROLS AND CONNECTORS.
3-4. Front and rear panel controls and c onnec tors ar e
shown in Figures 3-2 and 3-3.
3-5. OPERATING PROCEDURES.
3-6. The 7702A System is ready for use following
installation, discussed in Section II. Figure 3-4 describes
the Permapaper loading procedure, and Figure 3-5
provides step-by-step operating instructions, for normal
operation of the instrument. Figure 3-6 provides
instructions for rem ote operation of the c hart drive s tart stop and marker functions.
Figure 3-1. Typical 2-Channel Recording
3-1
TM 11-6625-2751-14&P
1 STOP pushbutton switch (momentary). Controls chart drive.
2 CHART SPEED pushbutton switches select chart speed. Pressing any of four pushbuttons starts chart drive at
speed selected.
3 MM/SEC-MM/MIN pushbutton switches. Selects mm/sec drive speeds for standard recorder. Selects mm/min
drive speeds when Option 11 or Option 12 is installed in recorder.
4 TIMER pushbutton switch (push on, push off). Initiates one per second timing pulse on lower edge of chart. One
per minute timing pulse is available (Option 13 and Option 14) for use with mm/min drive speeds.
5 MARK pushbutton switch (momentary). Controls operation of marker at lower edge of chart. Reference mark is
recorded when pushbutton is pressed.
6 POWER pushbutton switch (push on, push off). Controls line power to the recorder. Indicator lamp to the right of
the power switch lights when the power is on.
7 9 DAMPING controls. Adjusts the amount of feedback from the galvanometer windings to the driver amplifiers, to
obtain optimum galvanometer pulse response. One control per channel
8 10 HEAT controls. Adjusts amount of stylus heat to obtain the desired trace intensity. One control per channel
11 PREAMPLIFIER controls. Refer to the preamplifier instruction manuals for a description of the panel controls.
Figure 3-2. Front Panel Controls
3-2
TM 11-6625-2751-14&P
1 SIGNAL INPUT connector. Input for Channel 2.
2 SIGNAL MONITOR connector. Output of Channel 2 preamplifier, for connection to
monitoring instruments. Includes connections for carrier excitation and servo
reference voltages.
3 REMOTE MARK jack. Mates with external marker switch circuit, for control of
marker on chart paper.
4 SIGNAL INPUT connector. Input for Channel 1.
5 SIGNAL MONITOR connector. Output of Channel 1 preamplifier, for connection to
monitoring instruments. Includes connections for carrier excitation and servo reference
voltages.
6 AUXILIARY MARK jack. Mates with external switch circuit for control of auxiliary
marker on chart paper.
7 POWER INPUT connector. Mates with power cable supplied with the instrument.
8 LINE VOLTAGE slide switch. Controls power supply input connections. CHECK THAT
SWITCH IS SET FOR NOMINAL VOLTAGE OF EXTERNAL POWER SOURCE.
9 FUSE holder. Contains the input power fuse (1.5 amp slow-blow for 115 volts, 0.8 amp
slow-blow for 230 volts).
10 REMOTE RUN connector. Mates with external switch circuit for control of recorder
chart drive start-stop function.
11 LOCAL-REMOTE switch. Selects either front panel switch or remote run circuit for
control of recorder start-stop function.
12 Spare FUSE holder. Contains spare line fuse.
Figure 3-3. Rear Panel Controls
3-3
TM 11-6625-2751-14&P
RELEASE PAPER TABLE. Turn instrument OFF,
and open the recorder cover. Push the writing
table lock lever toward the galvanometers.
REMOVE SUPPLY SPOOL. Lift the paper table
outward and rest it on the takeup spindle. Lift the
supply spool out of the support brackets. Pull the
end discs apart to remove the paper core.
RELEASE PAPER TABLE. Turn instrument OFF,
and open the recorder cover. Push the writing
table lock lever toward the galvanometers.
REMOVE SUPPLY SPOOL. Lift the paper table
outward and rest it on the takeup spindle. Lift the
supply spool out of the support brackets. Pull the
end discs apart to remove the paper core.
Figure 3-4. Permapaper Loading Procedures
3-4
TM 11-6625-2751-14&P
FEED PAPER RNTO DRIVE ROLL. Fold back and
crease the paper about 1 inch from the end of the roll.
Start chart drive at 5 mm /sec. Insert the paper into the
drive roll squarely, so that the entire leading edge of the
paper contacts the drive roll. Stop the r ec order when the
paper is drawn tightly over the paper table. Lock the
paper table.
THREAD PAPER ONTO THE T AKEUP SPINDLE. Turn
on chart drive at 5 mm /sec, and loop paper around the
spindle tightly. The paper will be drawn onto the rotating
spindle. Stop the recorder. (The paper takeup f eature
must be used for satisfactory recorder operation.)
RECORDER IS READY FOR USE. Close the recorder
cover. A printed star appears on lower edge of chart, 30
feet from end of roll, to indicate remaining footage.
TO REMOVE PAPER AFTER RECORDING. Remove
the paper takeup spindle. Press the black plas tic button
on the end of the spindle. Pull out the upper and lower
ends of the spindle. After sliding the rec ording paper of f,
re-install the spindle, lower end first.
Figure 3-4. Permapaper Loading Procedures (Cont.)
3-5
TM 11-6625-2751-14&P
1 Connect 7702A System to power line, and connect input signals to J1 and J2 on the rear recorder
panel. Rotate preamplifier attenuator or function switch to the OFF position. For 8801A, 8802A
preamplifiers, place signal use-off switch in OFF position.
2 Press POWER pushbutton. Indicator lamp on recorder will light. Allow three minutes warmup time.
3 Balance and calibrate pream plifiers following the procedures outlined in the pream plifier instruction
manual. When making calibration adjustments, set chart drive ON (see Step 4).
4 Press MM/SEC pushbutton, then press "5" pushbutton. Recorder will run at 5 mm /sec chart speed.
(When recording data, press numbered speed pushbutton to suit recording application. Select
mm/min speeds with recorder Options 11 or 12 by pressing MIN pushbutton.)
5 Adjust stylus heat for each channel to obtain a satisfactory trace intensity (when recording data which
is in the upper range of the recorder bandwidth, a higher stylus heat is required for good trace
definition).
6 Press STOP pushbutton to stop chart drive.
7 Press TIMER pushbutton to obtain one per second time markings on recording. For mm/min
speeds, optional timer records one mark per minute.
8 Press MARK pushbutton to record reference marks on lower edge of Permapaper.
Figure 3-5. System Operating Procedures
3-6
TM 11-6625-2751-14&P
REMOTE CHART DRIVE CONTROL
1 Connect the switch circuit shown in Figure 2-8 to J13 on the rear panel of the recorder.
2 Place the LOCAL-REMOTE switch in the REMOTE position.
3 Press speed pushbuttons on the recor der front panel for the desired recor ding speed. W ith r emote
switch in RUN position, chart drive is ON. In STANDBY position, chart drive is OFF.
REMOTE MARKER CONTROL
4 Connect the switch circuit shown in Figure 2-9 to J15 on the r ecorder rear panel. Press the r emote
mark switch to record a reference mark on the lower edge of the Permapaper.
5 For systems with an auxiliary marker (Option 15), connect the switch circuit of Figure 2-9 to J14.
Press the auxiliary marker switch to record a reference mark between channels on the Permapaper.
Figure 3-6. Remote System Operation
3-7
SECTION IV.
PRINCIPLES OF OPERATION
TM 11-6625-2751-14&P
4-1. INTRODUCTION.
4-2. This section of the manual contains the
principles of operation of the electrical and mechanical
components in the 7702A System. A block diagram of
the system is shown in Figure 4-1. Introductory
paragraphs 4-3 to 4-13 contain basic information on
semiconductor diode and transistor circuits used in the
recording system.
4-3. BASIC CIRCUITS.
4-4. Diodes.
4-5. Semiconductor diodes are used in the signal
handling circuits and in the power supply rectifier and
regulator circuits.
4-6. Diodes are used as lim iters or clipper s in circ uits
to remove positive or negative peaks of wavefor m s. T he
diode can be used either as a waveform shaping circuit
or as a protective device to pr event excessive voltages
being applied to a sensitive circuit. Figure 4-2 (a) s hows
a limiter which prevents the negative peak of a pulse
from going more negative than approxim ately 0.6 volts.
Note that for a conducting silicon diode, the cathode
voltage is about 0.6 to 0.8 volts more negative than the
anode.
4-7. A diode clamper or dc restorer is a c ircuit which
establishes either the positive or negative peak of a
waveform at a particular dc refer ence voltage to provide
a definite baseline voltage for the waveform . Figure 4-2
(b) shows a clamper which provides a baseline of about
+20 volts for a negative pulse.
4-8. A diode regulator circuit uses either the constant
reverse-bias breakdown voltage characteristics of a
zener diode, or the constant forward bias voltage drop
characteristic of a s ilicon diode. Power supply reference
voltages are generally provided by break-down diodes
which maintains a constant voltage when supplied with a
reverse-bias voltage greater than their specified
breakdown voltage. Regulated voltages can also be
provided by a forward-biased silicon diode which
maintains a constant 0.6 to 0.8 volt drop. Figure 4-2 (c)
shows connections for both types of diodes.
4-9. Transistors.
4-10. Transistors are used throughout the 7702A in
amplifier and oscillator circuit configurations. Vacuum
tubes and transistors are functionally similar. In the tube,
a small grid-to-ca thode potential controls a large plate to
cathode current flow. In a transistor, a small base-toemitter current controls a large collector-to-emitter
current. A comparison of basic
Figure 4-1. Model 7702A System Block Diagram
4-1
Figure 4-2. Basic Diode Circuits
TM 11-6625-2751-14&P
Figure 4-3. Transistor Operation
4-2
TM 11-6625-2751-14&P
vacuum tube, NPN transistor, and PNP transistor
operation is shown in Figure 4-3 (a); indicated current
represents conventional flow of positive charges external
to the transistor and is not intended to indicate flow of
carriers inside the transistor structure. Notice that the
effect of emitter-base-collector voltages is totally
reversed between NPN and PNP transistors; circuits
which are arranged for an NPN transistor usually function
normally for a PNP transistor if supply voltages are
reversed.
4-11. There are three basic am plifier types, Figure 4-3
(b). These am plifiers are used alone or in com binations
to form complex circuits.
4-12. COMPONENT CIRCUIT DESCRIPTION.
4-13. Preamplifiers.
4-14. The principles of operation for the 8800 Series
Preamplifiers ar e contained in the particular preamplifier
Operating and Service Manual. A list of the preamplifiers
is shown in Section I, Table 1-3. The pream plifier s ignal
input connectors (J1, J2) mounted on the rear of the
recorder include provision f or us e of a guar d s hield in the
signal input cable. Use of a guard shield contributes to a
high common-mode rejection ratio when floating input
preamplifiers such as the 8803A are installed in the
system. Additional information on the preamplif ier guard
shield circuit is contained in the preamplifier manual.
4-15. The output signal of each preamplifier is
connected to the input of a 7700-02A galvanometer
driver amplifier. T he preamplif ier output signals are als o
available at connectors J21 and J22 at the rear of the
recorder, for connection to oscilloscopes or other
monitoring instruments . Signal distribution in the 7702A
System is shown in Figure 4-4.
4-16. Driver Amplifiers.
4-17. Two 7700-02A Galvanometer Driver Amplifiers
are mounted on the rear panel of the power supply 7702-
60030. The driver amplifier block diagram is shown in
Figure 4-5.
4-18. The input signal and the galvanometer feed-back
signal shown in the block diagram are amplified by the
balanced amplifier Q1, Q2, and directly coupled to the
differential amplifier Q3, Q4. The signal driving Q1 is
limited in amplitude by the transistors Q8 and Q9 to a
value which will not overload the driver amplifier or drive
the galvanometer writing arm excessively. The singleended output from the Q3, Q4 stage is obtained from the
collector of Q4 and is fed to the base of Q5. T ransistor
Q5 operates as a Class A driver f or the complem entarysymmetry Class B emitter-follower power amplifier Q6,
Q7.
The amplifier output is connected to the galvanometer
drive coil. A galvanometer feedback signal is obtained
from the galvanometer drive coil and velocity coil, and
returned as an input to the balanced amplifier.
4-19. FEEDBACK CIRCUIT. The feedback circuit
provides an adjustable amount of galvanometer damping
and galvanometer frequency compensation to obtain
optimum galvanometer transient response and frequency
response characteristics. Galvanometer damping is
obtained by generating a feedback voltage proportional
to the galvanometer coil velocity, and inserting this
voltage into the driver amplifier circuit with a polarity as to
reduce the coil velocity. Frequency compensation is
achieved by an RC network in the feedback c irc uit, which
determines the amplitude of high frequency feedback
voltages returned to the balanced amplifier.
4-20. The feedback voltage is derived from two
sources; the galvanometer velocity coil output, and the
voltage drop across R24 (see Figure 4-6). The velocity
voltage component is proportional to galvanometer coil
velocity, to damp the galvanometer motion. The
DAMPING control selects the amount of this velocity
voltage component which gives the best damping
characteristics. The drive coil current through R24
produces a voltage at the base of Q2 with an amplitude
approximately equal to the Q1 input signal due to the
high ratio of open loop to closed loop gain. This
feedback action forces a current through the
galvanometer drive coil alm os t ex ac tly proportional to the
input voltage.
4-21. The DAMPING control is adjusted for the best
transient response, and the COMPENSATIO N control is
adjusted to match the high-frequency roll-off of the
galvanometer. Figure 4-7 shows the galvanometer
response both in the frequency and time domains to
illustrate different degrees of damping.
4-22. The underdamped condition in Figure 4-7 (a)
depicts a partially damped system, with the damping
supplied only by the shorted coil frame of the galvanmeter. This shorted frame is equivalent to a low
resistence, one-turn short-circuited coil winding. The
currents induced in this coil frame develop a damping
force which is proportional to the coil velocity, and is in a
direction as to reduce the velocity. In this case, the
galvanometer oscillates around its final value before
coming to rest. The overdamped condition is the result
of excessive feedback damping voltage. In this case,
the galvanometer approaches its final value slowly,
giving too slow a rise time for recording short-period
transient voltages.
4-23. The ideal waveshape is the result of properly
adjusting the feedback voltage. In this case, the
galvanometer approaches the final value quickly, and
settles to the final value with a slight overshoot (about
4%). This corresponds to 71% of c ritic al damping, which
provides the desired transient and frequency response.
4-3
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