HP 34702, 34750 schematic

TM 11-6625-2809-14 & P

TECHNICAL MANUAL

OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT AND

GENERAL SUPPORT MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS)

FOR

MULTIMETER ME-498/U (HEWLETT-PACKARD

MODEL 34702A) (NSN 6625-00-538-9794)

AND

INDICATOR ID-2101/U (HEWLETT-PACKARD

MODEL 34750A) (NSN 6625-00-538-9758)

HEADQUARTERS, DEPARTMENT OF THE ARMY

JUNE 1979

TM 11-6625-2809-14 & P

This manual includes copyright material reproduced by permission of the HEWLETT-PACKARD Company.

TECHNICAL MANUAL HEADQUARTERS

DEPARTMENT OF THE ARMY

No.11-6625-2809-14 & P Washington, DC

OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT AND

GENERAL SUPPORT MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS)

FOR

MULTIMETER ME-4981U (HEWLETT-PACKARD MODEL 34702A)

(NSN 6625-00-538-9794)

AND

INDICATOR ID-21011U (HEWLETT-PACKARD MODEL 34750A)

(NSN 6625-00-538-9758)

REPORTING OF ERRORS

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 Commander, US Army Communications and Electronics
Materiel Readiness Command, ATTN: DRSEL-ME-MQ, Fort Monmouth, NJ 07703.

14June1979

In either case a reply will be forwarded direct to you.

This manual is an authentication of the m anufacturer’s commercial literature which, through usage, has been found to
cover the data required to operate and maintain this equipm ent. Since the manual was not prepared In accor dance with
military specifications and AR 310-3, the format has not been structured to consider levels of maintenance.

i

Table of Contents TM 11-6625-2809-14 & P

TABLE OF CONTENTS

PART ONE

Section Page

0. INTRODUCTION........................................0-1

I. GENERAL INFORMATION........................1-1

1-1. Description....................................1-1

1-6. Specifications................................1-3

1-8. Options..........................................1-3

1-10. Accessories Available

(See Figure 1-2)............................1-3

1-11. Instrument and Manual

Identification .................................1-3

Section Page

II. INSTALLATION..........................................2-1

2-1. Introduction ...................................2-1

2-3. Initial Inspection.............................2-1

2-5. Power Requirements ....................2-1

2-7. Grounding Requirements .……….2-2

2-10. Environmental Requirements .……2-2

2-12. Instrument Mounting .....................2-2

2-13. Bench Use .…………....................2-2

2-15. Rack Use ......................................2-2

2-17. Repackaging for Shipment .…......2-2

2-21. Power Cords and Receptacles .….2-3

Section Page

III. OPERATING INSTRUCTIONS..................3-1

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

3-3. Rear Panel Features.....................3-1

3-5. Warm-Up.......................................3-1

3-7. Operation with Plug-On Modules..3-1

Section Page

IV. THEORY OF OPERATION...........4-1

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

4-3. Basic Measurement Sequence..................4-1

4-5. Analog Circuits...........................................4-1

4-4. Input Amplifier............................................4-1

4-8. Integrator....................................................4-2

4-10. Zero Detect Circuits....................................4-2

4-12. Auto-Zero Cycle..........................................4-2

4-14. Digital Processing Circuits..........................4-2

4-17. Data Clock (Refer to

Figure 4-8)..................................................4-4

4-19. Timing Generator Circuit (See

Figure 7-8)..................................................4-4

4-21. Zero Detect and Data Transfer

(Refer to Figure 4-10).................................4-4

4-23. Data Accumulator and Storage

(Refer to Figure 7-7)...................................4-6

Section Page

4-25. Data Display and Control Circuits

(Refer to Figure 4-11) .…….......................4-6

4-27. Reset Timing (See Figure 4-12) ................4-7

4-29. Least Significant Digit Blank

(Refer to Figure 7-8) .…….........................4-7

Section Page

V. MAINTENANCE ........................................5-1

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

5-3. Operational Checks ..................................5-1

5-6. Adjustment Procedures..............................5-1

5-8. Cover Removal..........................................5-2

5-10. Adjustment Locator ...................................5-2

5-12. Power Supply Adjustment .…....................5-2

5-13. Input Amp. Offset Adjustment ……............5-2

5-14. Zero Detect Comparator Offset ….............5-2

5-15. Zero Detect Hysteresis

Adjustment .………….................................5-2

5-16. Reference Voltage Adjustments …............5-3

Section Page

VI. IDENTIFICATION OF PARTS ..................6-1

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

6-4. Deleted
6-6. Deleted

6-8. Proprietary Parts .…………….....................6-1

Section Page

VII. CIRCUIT DIAGRAMS AND

TROUBLESHOOTING .………..................7-1

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

7-3. Troubleshooting .………............................7-1

7-4. Troubleshooting Trees .……......................7-1

7-6. Troubleshooting Procedures .....................7-1

7-8. Functional Block Diagram

(Figure 7-4) .………...................................7-1

7-10. Timing Circuits (Figure 7-5) ......................7-1

7-12. Schematic Diagrams (Figures

7-6, 7-7 and 7-8) .……...............................7-1

7-14. Component Location Diagrams ................7-1

APPENDIXES

A. Difference Data Sheet ...............................A-1

B. References ................................................B-1

C. Maintenance Allocation .…………………..C-1
D. Repair Parts And Special

Tools List...................................................D-1

ii

Table of Contents TM 11-6625-2809-14 & P

LIST OF TABLES

Table Page

1-1. Specifications................................................ 1-2

1-2. General Information ...................................... 1-3

3-1. 34721B/5055A Output Codes....................... 3-1

5-1. Recommended Test Equipment ................... 5-1

5-2. DC Accuracy ................................................. 5-2

5-3(a). AC Accuracy (45 Hz and 20 kHz................... 5-5

5-3(b). AC Accuracy (100 kHz).................................5-6

5-4. Accuracy Test .............................................. 5-7

6-1. Identification of Parts..................................... 6-3

LIST OF ILLUSTRATIONS

Figure Page

1-1 Instrument Serial Number............................1-1

2-1. Installation of the Model 34702A..................2-1

3-1. Front add Rear Panel Features....................3-0

4-1. Block Diagram..............................................4-0

4-2. ACV/DCV Attenuator....................................4-1

4-3. W Converter.................................................4-2

4-4. AC/DC Converter......................................... 4-3

4-5. Impedance Converter...................................4-4

5-1. Input Impedance Test ..................................5-3

5-2. Effective Common Mode Rejection..............5-3

5-3. Normal Mode Rejection................................5-4

5-4. Removal from Case .....................................5-8

5-5. Adjustment Locator...................................... 5-9

7-1. AC Converter Troubleshooting Tree............7-3/7-4

7-2. W Converter Troubleshooting Tree..............7-3/7-4

7-3. 34702A Schematic.......................................7-5/7-6

iii

TABLE OF CONTENTS

PART TWO

TM 11-6625-2809-14 & P

Section Page

I. GENERAL INFORMATION........................1-1

1-1. Description....................................1-1

1-6.Specifications.......................................1-3

1-8. Options..........................................1-3

1-10. Accessories Available

(See Figure 1-2) ...........................1-3

1-11. Instrument and Manual

Identification .……….....................1-3

Section Page

II. INSTALLATION .........................................2-1

2-1. Introduction....................................2-1

2-3. Initial Inspection.............................2-1

2-5. Power Requirements.....................2-1

2-7. Grounding Requirements..............2-2

2-10. Environmental Requirements........2-2

2-12. Instrument Mounting......................2-2

2-13. Bench Use.....................................2-2

2-15. Rack Use.......................................2-2

2-17. Repackaging for Shipment............2-2

2-21. Power Cords and Receptacles......2-3

Section Page

III. OPERATING INSTRUCTIONS..................3-1

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

3-3. Rear Panel Features.....................3-1

3-5. Warm-Up.......................................3-1

3-7. Operation with Plug-On Modules .3-1

Section Page

IV. THEORY OF OPERATION........................4-1

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

4-3. Basic Measurement Sequence ....4-1

4-5. Analog Circuits..............................4-1

4-6. Input Amplifier...............................4-1

4-8. Integrator.......................................4-2

4-10. Zero Detect Circuits.......................4-2

4-12. Auto-Zero Cycle.............................4-2

4-14. Digital Processing Circuits.............4-2

4-17. Data Clock (Refer to

Figure 4-8).....................................4-4

4-19. Timing Generator Circuit (See

Figure 7-8).....................................4-4

4-21. Zero Detect and Data Transfer

Circuits (Refer to Figure 4-10).......4-4

4-23. Data Accumulator and Storage

(Refer to Figure 7-7)......................4-6

Section Page

4-25. Data Display and Control Circuits

(Refer to Figure 4-11)...................4-6

4-27. Reset Timing (See Figure4-12)..................4-7

4-29. Least Significant Digit Blank

(Refer to Figure 7-7)..................................4-7

Section Page

V. MAINTENANCE.........................................5-1

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

5-3. Operational Checks ..................................5-1

5-6. Adjustment Procedures..............................5-1

5-8. Cover Removal .........................................5-2

5-10. Adjustment Locator....................................5-2

5-12. Power Supply Adjustment..........................5-2

5-13. Input Amp. Offset Adjustment ...................5-2

5-14. Zero Detect Comparator Offset ................5-2

5-15. Zero Detect Hysteresis

Adjustment.................................................5-2

5-16. Reference Voltage Adjustments ...............5-3

Section Page

VI. IDENTIFICATION OF PARTS...................6-1

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

6-4. Deleted
6-6. Deleted

6-8. Parts Changes...........................................6-1

6-10. Proprietary Parts

Section Page

VII. CIRCUIT DIAGRAMS AND

TROUBLESHOOTING...............................7-1

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

7-3. Troubleshooting.........................................7-1

7-4. Troubleshooting Trees...............................7-1

7-6. Troubleshooting Procedures......................7-1

7-8. Functional Block Diagram

(Figure 7-4)................................................7-1

7-10. Timing Circuits (Figure 7-5).......................7-1

7-12. Schematic Diagrams (Figures

7-6, 7-7 and 7-8)........................................7-1

7-14. Component Location Diagrams.................7-1

Appendix Page

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

A. Difference Data Sheet.................................A-1

iv

Table of Contents

TM 11-6625-2809-14 & P

LIST OF ILLUSTRATIONS

Figure Page

1-1. Plug-On Modules which can be used

with the 34750A Display Module................1-1

1-2. Accessories Available for use with 34750A.. 1-2
1-3. Instrument Serial Number (on rear panel) .1-3

2-1. Voltage Selection........................................2-1

2-2. Rick Mount Kits..........................................2-2

2-3. Power Receptacles....................................2-3

3-1. 34750A Rear Panel....................................3-1

4-1. Basic Block Diagram of 34750A.................4-0

4-2. Simplified Diagram of the

Input Amplifier............................................4-1

4-3. Simplified Diagram of the

Integrator Circuit.........................................4-2

4-4. Simplified Diagram of Zero Detect

Circuits......................................................4-2

4-5. 34750A Circuits shown in Auto-Zero

Mode ......................................................4-3

4-6. Block Diagram of Typical ASM...................4-3

4-7. ASM Simplified Block Diagram...................4-4

4-8. Data Clock..................................................4-4

Figure Page

4-9. 34750A Flow Chart....................................4-5

4-10. Zero Detect and Data Transfer

Timing......................................................4-6

4-11. Data Display Circuits..................................4-6

4-12. Reset Tuning .............................................4-7

5-I. 11456A Readout Test Card.......................5-1

5-2. Cover Removal..........................................5-2

5-3. Zero Detect Comparator Offset

Adjustment.................................................5-2

5-4. Chassis Mounted Component and

Adjustment Locator....................................5-3

7-1. Power Supply Troubleshooting

Tree ................................................7-3/7-4

7-2. Analog Troubleshooting Tree.....................7-5

7-3. Digital Troubleshooting Tree................7-7/7-8

7-4. Functional Block Diagram..................7-9/7-10

7-5. Timing Waveforms...........................7-11/7-12

7-6. Analog Signal Processor..................7-13/7-14

7-7. Digital Signal Processor...................7-15/7-16

7-8. Power Supply...................................7-17/7-18

LIST OF TABLES

Table Page

1-1. 3470A Series Signal Conditioning

Modules.........................................................1-3

1-2. Available Options..............................................1-3

5-1. Recommended Test Equipment.......................5-1

5-2. Operational Checks..........................................5-1

6-1. Identification of Parts........................................6-2

7-1. Troubleshooting Trees......................................7-1

v

hp

PART ONE

OPERATING AND SERVICE MANUAL

Binder part No. 34740-90011

(Includes cover sheet)

Manual Part No. 34740-90012 or 34750-90012

(Binder, System Introduction and Display Manual)

MODEL 3470

MEASUREMENT SYSTEM

TM 11-6625-2809-14 & P

IMPORTANT NOTICE

This instruction manual requires no change sheet. Any
change information has already been integrated into the
manual by page revisions. Revised pages have a
revision letter which can be found on the lower corner
of the page. Reference may also be made to Section VIII
of each manual where backdating information for earlier
instruments can be found.

Copyright Hewlett-Packard Company 1972

P.O. Box 301, Loveland, Colorado 80537 U.S.A.

vi

Printed: June 1973

TM 11-6625-2809-14 & P

hp

HEWLETT PACKARD

CERTIFICATION

Hewlett-Packard Company certifies that this instrument met its published specifications at the time of
shipment from the factory. Hewlett-Packard Company fur ther certifies that its calibration meas urements

are traceable to the United States National Bureau of Standards, to the ex tent allowed by the Bureau’s
calibration facility, and to the calibration facilities of other International Standards Organization members.

WARRANTY AND ASSISTANCE

This Hewlett-Packard produc t is warranted against defects in materials and work manship f or a period of
one year from the date of shipment, except that in the case of certain components, if any, listed in
Section I of this operating manual, the warranty shall be for the specif ied period. Hewlett-Pack ard will, at
its option, repair or replace products which prove to be defective dur ing the warranty period provided they
are returned to Hewlett-Packard, and provided the proper preventive maintenance procedures as listed in
this manual are followed. Repairs necessitated by misuse of the product are not covered by this
warranty. NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. HEWLETT-PACKARD IS NOT LIABLE FOR CONSEQUENTIAL DAMAGES.

If this product is sold as part of a Hewlett-Packard integrated instrument system, the above warranty shall
not be applicable, and this product shall be covered only by the system warranty.

Service contracts or customer assistance agreements are available for Hewlett-Packard products.
For any assistance, contact your nearest Hewlett-Packard Sales and Service Office, Addresses are

provided at the back of this manual.

vii

INTRODUCTION

TM 11-6625-2809-14 & P

The 3470 Measurement System is a series of modules
that may be plugged together to form several different
measuring instrum ents, including both line powered and
battery powered versions.

A mainframe display module is connected to a bottom
plug-on function module to form a complete instrument.

The BCD and/or Battery plug-on module m ay be added
between the display and function modules as desired.

Refer to the Operating and Service Manual of the plug­on module to be used with the display module for the
operating instructions, incoming inspection, and adjust­ment procedures of the instrument as a whole.

Possible Instrument Configurations

viii

INTRODUCTION

0-1. SCOPE.

a. This manual in Part 1, describes
Multimeter ME-498/U (fig. 3-1) and provides instructions
for operation and maintenance. Throughout this manual
the ME-498/U is referred to as the Hewlett-Packard
Model 34702A.

SECTION 0

TM 11-6625-2809-14 & P

Improvement Report) as prescribed in AR
70058/NAVSUPINST 4030.29/AFR 71-13/MCOP40

30.29A and DLAR 4145.8.
c.

Discrepancy in Shipment Report

(DISREP) (SF 361). Fill out and forward Discrepancy in

Shipment Report (DISREP) (SF 361) as prescribed in
AR 55-38/NAVSUPINST 4610.33B/AFR 7518/MCO
P4610.19C and DLAR 4500.15.

b. Part 2 describes Indicator ID-2101/U
(fig.1-1, Part 2). This display module is referred to as the
Hewlett-Packard Model 34750A.

0-2. INDEXES OF PUBLICATIONS.

a.
of DA Pam 310-4 to determine whether there are new
editions, changes, or additional publications pertaining to
the equipment.

b.
to determine whether there are modification work orders
(MWO’s) pertaining to the equipment.

0-3. FORMS AND RECORDS.

a.

DA Pam 310-4.

DA Pam 310-7.

Reports of Maintenance and

Unsatisfactory Equipment.

and reports which are to be used by maintenance
personnel at all maintenance levels are listed in and
prescribed by TM 38-750.

b.

Deficiencies.

Report of Packaging and Handling

Fill out and forward DD Form 6 (Pac kaging

Refer to the latest issue

Refer to DA Pam 310-7

Maintenance forms, records,

0-4. REPORTING EQUIPMENT

IMPROVEMENT RECOMMENDATIONS (EIR).

EIR’s will be prepared using 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 Communication and Electronics Materiel
Readiness Command, ATTN: DRSEL-ME-MQ, Fort
Monmouth, NJ A reply will be furnished direct to you.

0-5. ADMINISTRATIVE STORAGE.

Administrative storage of equipm ent issued to and used
by Army activities shall be in accordance with TM 740­90-1 and paragraph 2-8.

0-6. DESTRUCTION OF ARMY ELECTRONICS
MATERIEL.

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

0-1

Model 34702A TM 11-6625-2809-14 & P

SECTION I

GENERAL INFORMATION

1-6. Table 1-1 lists specifications for the Model

1-1. INTRODUCTION.

34702A Multimeter. This table supersedes all other

previously printed specifications. Procedures are
1-2. This manual contains installation and operating
instructions as well as maintenance information which
includes performanc e checks for the Model 34702A. A
schematic diagram, theory of operation, and
troubleshooting information are provided for use in
maintaining the 34702A Multimeter Module.

provided in Section V to verify performance of the

instrument to its specifications and to readjust the

instrument if required. T he accuracy specifications apply

for ambient temperatures of 23

0

C+ 50C. For
temperatures outside this range, a temperature
coefficient factor (listed in Table 1-1) must be used.

1-3. DESCRIPTION.

1-4. The Hewlett-Packard Model 34702A Multimeter
is a signal conditioning module that m ay be connected to
a Model 34740A or 34750A Display Module, to measur e
AC Voltage, DC Voltage, or resistance. The AC and DC
volts functions provide four decade ranges from I V to
1000 V. Six resistance ranges from 100 full sc ale to 10
MQ full scale are provided by the "Ω (fy)" function. Each
available range of the Model 34702A has 100%
overranging capability except the 1000 V range which
has 20%.

Overload protection circuits allow up to
1200 V peak to be applied to the INPUT
V terminals without damaging the
instrument. Up to 350 V can be applied
to the INPUT S terminals without
damaging the instrument. No more than
500 V should be applied between LO
and Chassis. Do not apply voltage
between LO and Chassis when using
the 34721A or 34721B BCD Module.
These modules connect LO to Chassis
when attached to the Model 34 702A.

1-7. Table 1-2 lists general information relating to the
instrument.

1-8. INSTRUMENT AND MANUAL

IDENTIFICATION.

1-9. A three-section serial number (xxxxAxxxxx) is
used to identify your Model 34702A. Figure 1-1
illustrates the meaning of the three parts of the number.

1-10. This manual is kept up-to-date with revised
pages. If the serial number of your instrument is lower
than the one on the title page of this manual, refer to the
backdating inform ation in Appendix A which adapts this
manual to your instrument. All correspondence with
Hewlett-Packard Company should include the complete
serial number.

1-5. SPECIFICATIONS AND GENERAL

INFORMATION.

Figure 1-1. Instrument Serial Number.

1-1

Model 34702A TM 11-6625-2809-14 & P

Table 1-1. Specifications. (Measured using 34740A or 34750A Display Unit)

DC VOLTAGE
34740A

Performance:

Accuracy (+ 230C t 50C), < 95% RH)

30 days + (0.03% of reading + .01% of range)
90 days + (0.04% of reading + .01% of range)
6 mo. + (0.05% of reading + .02% of range)
1 yr. + (0.06% of reading + .02% of range)

Stability (24 hours, + 230C + 1°C)

+ (0.01% of reading + 0.005% of range)

Temperature Coefficient (00 C to + 500C)

DC voltage: t (0.0035% of reading + 0.001%

of range)/oC.

Input Characteristics:

Input resistance

1 and 10 V ranges: 11.11 M + 0.2%
100 V range: 10.1 M + 0.2%
1000 V range: 10 M + 02%

Effective Common Mode Rejection (1 k unbalance)

DC: > 80 dB.*

Input impedance

1 and 10 V ranges: 11.11 M + 02%/ /80 pF max.
100 V range: 10.1 M ± 0.2%/ /80 pF max.
1000 V range: 10 M + 0.2%/180 pF max.

OHMS
34740A

Performance:

Accuracy (+ 230C ± 50C,< 95% RH)

30 days

10 MO range + (0.25% of reading + 0.02%

of range)

All other ranges + (0.05% of reading + 0.02%

of range)

90 days

10 M range + (0.30% of reading + 0.02%

of range)

All other ranges + (0.06% of reading + 0.02%

of range)

6 mo.

10 M range + (0.35% of reading + 0.03%

of range)

All other ranges + (0.07% of reading + 0.03%

of range)

Normal Mode Rejection

50 Hz (Option 050): >60dB (50 Hz + 0.1%)
60 Hz (Option 060): >60dB (60 Hz + 0.1%)

*Does not apply when BCD Module is used.

AC VOLTAGE
34740A

Performance:

Accuracy (+ 23°C + 50C, <95% RH)

30 days

45 Hz to 20 kHz + (0.25% of reading + .05%

of range)

20 kHz to 100 kHz + (0 75% of reading + .05%

of range)

90 days

45 Hz to 20 kHz + (0.30% of reading + .05%

of range)

20 kHz to 100 kHz + (0.80% of reading + .05%

of range)

6mo.

45 Hz to 20 kHz + (0.35% of reading + .05%

of range)

20 kHz to 100 kHz + (085% of reading + .05%

of range)

1 yr.

45 Hz to 20 kHz + (0.50% of reading + 0.05%

of range)

20 kHz to 100 kHz + (1.0% of reading + 0.05%

of range)

Temperature Coefficient (0°C to + 500C)

AC voltage: ± (0,03% of reading + 0.001%

of range) /0C.

Stability (24 hours, + 23°C + 1°C)

AC voltage: 45 Hz to 20 kHz: ± (0.15% of reading

+ 0.05% of range)
20 kHz to 100 kHz: + (0.4% of reading
+ 0.05% of range)

Response Time: < 2 s within + 0.3% of final value or 20

counts, whichever is greater.

Input Characteristics:

1 yr.

10 M range ± (0.50% of reading + 0.03%

of range)

All other ranges t (0.11% of reading + 0.03%

of range)

Stability (24 hours, 23°C + 10C)

10 Mn range + (0.1% of reading + 0.01%

of range)

All other ranges + (0.02% of reading + 0.02%

of range)

Temperature Coefficient (00C to + 500C)

Ω

10 Ml range: + (0.035% of reading + 0.001%

of range) / C.

All other ranges' t (0.006% of reading + 0.001%

of range) / C.

DC VOLTAGE
34750A

Performance:

Accuracy (+ 23°C + 50C), < 95% RH)

30 days ± (0.025% of reading + .005% of range)
90 days + (0.035% of reading + .005% of range)
6 mo. + (0.045% of reading + .007% of range)
1 yr. + (0.06% of reading + .01% of range)

NOTE: Due to temperature change inside the instrument

between line and battery operation, the references
must be adjusted when changing modes to achieve
these specifications

Stability (24 hours, + 230C + 10C)

DC voltage: + (.008% of reading i .004% of range)

Temperature Coefficient (0°C to + 500C)

DC voltage: ± (0.0025% of reading + 0.0002% of

range) / C

Input Characteristics

Input resistance

1 and 10 V ranges: 11.11 M + 0.2%
100 V range: 10.1 M +.0.2%
1000 V range: 10 M + 0.2%

Effective Common Mode Rejection (1 kO unbalance)

DC: >80 dB.*

*Does not apply when BCD Module is used

Rev. A 1-2

Model 34702A TM 11-6625-2809-14 & P

Table 1-1. Specifications (Cont’d).

Normal Mode Rejection

50 Hz (Option 050): >60 dB (50 Hz + 0.1%)
60 Hz (Option 060): >60 dB (60 Hz + 0.1%)

AC VOLTAGE
34750A

Performance:

Accuracy (+ 230 + 5C, A 95% RH)

30 days

45 Hz to 20 kHz +(0.25% of reading + .05%

of range)

20 kHz to 100 kHz + (.75% of reading + .05%

of range)

90 days

45 Hz to 20 kHz + (.3% of reading + .05%

of range)

20 kHz to 100 kHz + (.8% of reading + .05%

of range)

6 mo.

45 Hz to 20 kHz ± (.35% of reading + .05%

of range)

20 kHz to 100 kHz + (.85% of reading + .05%

of range)

1 yr.

45 Hz to 20 kHz + (0.50% of reading + 0.05%

of range)

20 kHz to 100 kHz ± (1.0% of reading + 0.05%

of range)

Stability (24 hours, + 230C ± 10 C)

AC voltage: 45 Hz to 20 kHz: + (0.15% of reading

+ 0.05% of range)

20 kHz to 100 kHz: + (0.4% of reading

+ 0.05% of range)

Temperature Coefficient (0oC to + 50°C)

AC voltage: + (0.03% of reading + 0.001%

of range) /°C

Response Time: < 2 s within + 0.3% of final value or 200

counts, whichever is greater.

Input Characteristics:

Input impedance

1 and 10 V ranges: 11.11 M + 0.2%/1 /80 pF max.
100 V range: 10.1 M + 0.2%1/80 pF max.
1000 V range: 10 M + 0.2%/ /80 pF max.

OHMS
34750A

Performance:

Accuracy (+ 23oC + 5°C, < 95% RH)

30 days

10 M range ±(0.25% of reading + 0.015%

of range)

All other ranges + (0.045% of reading + 0.015%

of range)

90 days

10 M range ± (0.3% of reading + 0.015%

of range)

All other ranges + (0.055% of reading + 0.015%

of range)

6 mo.

10 M range ± (0.35% of reading + 0.02%

of range)

All other ranges + (0.065% of reading + 0.02%

of range)

1 yr

10 M range ± (0.50% of reading + 0.02%

of range)

All other ranges + (0.11% of reading + 0.02%

of range)

NOTE: Due to temperature change inside the instrument

between line and battery operation, the references
must be adjusted when changing modes to achieve
these specifications.

Stability (24 hours, 23°C ± 1oC)

10 M range + (0.1% of reading + 0.009% of range)
All other ranges + (0.2% of reading + 0.015% of range)

Temperature Coefficient (0o C to + 50o C)

10 M range: ± (0.035% of reading + 0.001%

of range) /°C

All other ranges: +(0.006% of reading + 0.001%

of range) /oC

DC VOLTAGE
34740A

Ranges:

Full Scale Maximum

Range Reading Reading

1 V ± 1.0000 V ± 1.9999 V

10 V ± 10.000 V ± 19.999 V

100 V ± 100.00 ±199.99 V

1000 V + 1.0000 V ±1200.0 V

Overrange

1000 V range: 20%.
All other ranges: 100% (19999 max reading)

Range Selection: manual pushbuttons

Performance:

Reading Rate

Option 050 (50 Hz): 8/s fixed

Option 060 (60 Hz): 5/s fixed

Table 1-2. General Information.

Input Characteristics:

Input terminals: floating pair.*
Maximum input voltage

High to low 1200 V
Low to Chassis + 500V*

*Does not apply when BCD Module is used.

AC VOLTAGE
34740A

Ranges:

Full Scale Maximum

Range Reading Reading

1 V 1.0000 V 1.9999 V

10 V 10.000 V 19.999 V

100 V 100.001 199.99 V

1000 V 1.0000 V 1200.0 V

Rev. A 1-3

Model 34702A TM 11-6625-2809-14 & P

Table 1-2. General Information (Cont’d).

Overrange

1000 V range: 20%
All other ranges: 100% (19999 max reading)

Range selection- manual pushbuttons

Performance:

Frequency range: 45 Hz to 100 kHz

Input Characteristics:

input terminals: floating pair. *

Maximum input voltage

High to low: 1200 V rms. Except 1 V range.
1 V Range:

1200 V rms maximum 45 Hz - 200 Hz
300 V rms maximum 200 Hz - 100 kHz

Low to Chassis: + 500 V *

* Does not apply when BCD Module is used.

Ω

34740A

Ranges:

Range

100 Ω

1 κΩ

10 κΩ

100 κΩ

1000 κΩ

10 ΜΩ

Full Scale

Reading

100.00 Ω

1.0000 ΚΩ

10.000 ΚΩ

100.00 ΚΩ

1000.0 ΚΩ

10.000 ΜΩ

Maximum

Reading

199.99 Ω

1.9999 ΚΩ

19.999 ΚΩ

199.99 ΚΩ

1999.9 ΚΩ

19.999 ΜΩ

Overrange

1000V range: 20%

All other ranges 100% (199999 max reading)
Range selection: manual pushbuttons
Reading rate

Option 050 (50 Hz): 4/s fixed

Option 060 (60 Hz). 5/s fixed
Input terminals: floating pair *
Maximum Input voltage

High to Low: + 1200 V

Low to Chassis: + 500 V·*

* Does not apply when BCD Module is used.

AC VOLTAGE
34750A

Ranges:

Range

1 V

10 V

100 V

1000 V

Overrange

1000 V range: 20%

All other ranges. 100% (199999 max reading)
Range selection: manual pushbuttons

Full Scale

Reading

1.00000 V

10.0000 V

100.000 V

1000.00 V

Maximum

Reading

1.99999 V

19.9999 V

199.999 V

1200.00 V

Overrange: 100% on all ranges
Range selection: manual pushbuttons

Input Characteristics:

Input terminals: floating pair (different from voltage

input terminals).

Current through measured resistor: 10 mA on 100 Ω

range decreasing one decade per successively high­er range.

Effective Common Mode Rejection: same as dc spec-

ifications.

Overload protection: + 350 V peak (248 V rms sine

wave).

Other:

Operating temperature: 0°C to + 50°C.
Storage temperature: - 40oC to + 75oC.
Line requirements: 100/120/220/240 V

- 10%, + 5% switchable:

DC VOLTAGE
34750A

48 Hz to 440 Hz; < 8.7 VA.

Ranges:

Range

1 V

10 V

100 V

!000 V

Full Scale

Reading

+ 1.00000 V
+ 10.0000 V
+ 100.000 V
+ 1000.00 V

Maximum

Reading

+ 1.99999 V
+ 19.9999 V
+ 199.999 V
+ 1200.00 V

Frequency range: 45 Hz to 100 kHz
Input terminals: floating pair
Maximum input voltage

High to Low: 1200 V rms except on 1 V range.

On 1 V range 2.5 x 105 V Hz limit with min­imum protection of 300 V rms.

Low Chassis: + 500 V

Ω

34750A

Ranges:

100 Ω 100.000 Ω 199.99 Ω

1 κΩ 1.00000 κΩ 1.99999 κΩ

10 κΩ 10.0000 κΩ 19.9999 κΩ

100 κΩ 100.000 κΩ 199.999 κΩ

1000 κΩ 1000.00 κΩ 1999.99 κΩ

10 ΜΩ 10.0000 ΜΩ 19.9999 ΜΩ
Overrange: 100% on all ranges
Range: selection manual pushbuttons
Input terminals: floating pair (different from voltage

input terminals).

Current through measured resistor: 10 mA on 100 Ω

range decreasing one decade per successively high­er range.

Effective Common Mode Rejection: same as dc spec-

ifications.

Overload protection- t 350 V peak (248 V rms sine

wave).

Rev. A 1-4

Model 34702A TM 11-6625-2809-14 & P

SECTION II

INSTALLATION

2-1. INTRODUCTION.

2-2. This section contains installation and shipping
information for the Model 34702A.

2-3. INITIAL INSPECTION.
2-4. The Model 34702A should be inspected upon

receipt for damage that might have occurr ed in transit. If
there is damage due to shipping, file a claim with the
carrier. If there are other electrical or mechanical
deficiencies refer to the warranty statement on the back
of the title page. Use the procedures pr ovided in Sec tion
V to check instrument performance.

2-5. CONNECTION TO THE DISPLAY MODULE.

2-6. Referring to Figure 2-1, connect the Model
34702A to the Display Module using the following
procedure:

a. Pull the side locks on the Display Module to the

rear.

b. Pos ition the Display Module and 34702A together
so that the tabs and slots on the sides of the two units
interlock.

c. Push the side locks toward the Display Module.
This pulls the two units together and locks them.

2-7. If a 34720A Battery Module or a 34721B BCD
Module is to be used between the display module and
the 34702A then the side locks on this middle module
hold the 34702A.

2-8. REPACKAGING FOR SHIPMENT.

2-9. If the instrument is to be shipped to Hewlett­Packard for service or repair, attach a tag to the
instrument describing the work to be accomplished and
identifying the owner of the instrument. Identify the
instrument by serial number, m odel num ber and nam e in
any correspondence. If you have any questions, contact
your local Hewlett-Packard Sales and Service Office.

2-10. If the original shipping container is to be used,
place the instrument in the container with appropriate
packing material and seal the container well with strong
tape or metal bands.

2-11. If an -hp- container is not to be used, use a
heavy carton or wooden box with an inner container.
Wrap the instrument with heavy paper or plastic and
place cardboard strips across the face for protection
before placing the instrument in the inner container. Us e
packing material around all sides of the inner container,
and seal the outer container well with strong tape or
metal bands. Mark the container with "DELICATE
INSTRUMENT" or "FRAG­ILE."

Figure 2-1. Installation of the Model 34702A

2-1

Model 34702A TM 11-6625-2809-14 & P

Figure 3-1. Front and Rear Panel Features.

3-0

Model 34702A TM 11-6625-2809-14 & P

SECTION III

OPERATING INSTRUCTIONS

3-1. INTRODUCTION.

3-2. This section contains instructions and info rmation
which will assist you in proper operation of the Model
34702A Multimeter Module. A Model 34740A or 34750A
Display Module is required to operate the Model 34702A.
Included in this section is identification of controls,
indicators and connectors; operating procedures; and
BCD output code information (for use in conjunc tion with
the 34721B BCD Module).

3-3. PANEL FEATURES.

3-4. The panel features of the instrument are
described in Figure 3-1.

3-5. FRONT PANEL OPERATION.

3-6. There are two manual controls; the function
switch and the range switch (See Figure 3-1). Each
range, except the 1000V range, has 100% overranging
capability; e.g. using a four digit display module 1.9999 V
can be measured on the I V range. T he display blanks
at 200% of range, indicating an overload.

Overload protection circuits allow up to
1200 V peak to be applied to the
INPUT V terminals without damaging
the instrument. Up to 350 V can be
applied to the INPUT Ω.

terminals without damaging the instrument. No
more than 500 V should be applied between LO
and Chassis (Grnd. ). Do not apply voltage
between LO and Chassis when using the 34721A or
34721B BCD Module. These modules connect LO
to Chassis when attached to the Model 34702A.

3-7. DC Voltage Measurement.

3-8. Set the Function switch to DCV, select the
required voltage range, and apply the voltage to be
measured to the INPUT V terminals.

3-9. AC Voltage Measurement.

3-10. Set the function switch to ACV, select the
required voltage range, and apply the voltage to be
measured to the INPUT V terminals.

3-11. Resistance Measurement.

3-12. Set the function switch to Ω (92), select the
required resistance range, and connect the device to be
measured to the INPUT Ω terminals.

3-13. 34721B/5055A OUTPUT CODES.

3-14. Output codes obtained from a 34721B BCD
Module when used in conjunction with the Model 34702A
and a display module are listed in Table 3-1. Refer to
the 34721B Operating and Service Manual for further
information regarding the BCD Module
.

Table 3-1. 34721B5055A Output Codes

Polarity

Number

Printed

0 DCV underrange O
1 + 10000 ACV overrange 1
2 1000 1000

3 100 100 3
41010 4
511 5

6.1.1 6
7 7
8 8
9 9

Overload

Column 9

Range

Column 8

Ω

k

Volts

Function

Column 7

Ω

k

3-1

Overrange

Column 6

Digits Columns

1 through 5

2

Model 34702A TM 11-6625-2809-14 & P

Figure 4-1. Block Diagram.

4-0

Model 34702A TM 11-6625-2809-14 & P

SECTION IV

THEORY OF OPERATION

4-1. INTRODUCTION.
4-2. This section contains a des cription of the Model

34702 Multimeter in simplified form followed by a more
detailed functional description. A detailed circuit
schematic is shown in Figure 7-3.

4-3. BLOCK DIAGRAM DESCRIPTION.

4-4. The circuits of the Model 34702A can be divided
into four major blocks shown in Figure 4-1.

4-5. ACV And DCV Attenuator.

4-6. The ACV/DCV Attenuator reduces the level of
the signal applied to the input so that it can be measur ed
by the 34740A or 34750A Display Module. The signal
can be attenuated by a factor of I, 10, 100 or 1000.

4-7. Current Source.

4-8. Resistance measurem ents are m ade by passing
a known current through the resistor being measured
and then measuring the voltage developed across the
resistor. The current source supplies five different
currents used by the six available ohmmeter ranges.
Resistance of an unknown is measured by connecting it
across the Ω terminals and selecting Ω function.

4-9-. Range/Function Switches

4-10. Range and Function switching is accomplished
by manual selection. Data from the Range and Function
switches is supplied to the Display Module, and to the
BCD Module when it is connected.

4-11. AC Converter.

4-12. The AC Converter accepts ac voltage from the
attenuator and changes it to a dc voltage proportional to
the level of the applied signal.

4-13. DETAILED THEORY OF OPERATION.

4-14 ACV/DCV Attenuator.

4-15. Figure 4-2 shows the ACV/DCV Attenuator with
its AC and DC voltage accuracy adjustments deleted.
Resistors R3, R5, and R7, shown in Figure 7.3 are dc
adjustments. Capacitors C3 through Cl 1, also shown in
Figure 7-j provide ac compensation for the attenuator.

4-16. Ω Converter.

4-17. Current Source. A simplified diagram of the

Ω

meter current source is shown in Figure 4-3a. Zener
diode CRI6 is the voltage reference for the current
source.

Figure 4-2. ACV/DCV Attenuator.

4-1

Model 34702A TM 11-6625-2809-14 & P

Amplifier A is connected in a non-inverting configuration
and R
range) is developed across R

is adjusted such that 1 V (.1 V for the 10MIO

b

and R

a

Amplifier B has its

b.

+ input connected to a stable dc voltage of -6.2 V. T he ­input is connected to the output of Amplifier A through
the range reference resistors R52 - R56. The I V ac ross

and Rb causes the output of Amplifier B to become

R

a

more positive. This allows the current through Qx to vary
such that the - input of Amplifier B becomes
approximately -6.2 V. The input current to Am plifier B is
very small. Consequently the current that flows through
the range reference resistors is the s ame as the current
supplied by the source of Qx. The drain current of Qx is
almost identical to its source current because the gate
current is extremely small. The drain current flows
through Rx and develops a dc voltage which is applied to

the Display Module input. The output current, I

, is

x

changed for different resistance ranges by changing the
value of R

On the 10 M Ω range

a.

Switch Sb is in the 10 M Ω position which reduces the
voltage between points 4 and 5 to .1 V.

4-18. Ohms Protection Circuit. The actual circuit
represented by Qx in Figure 4-3a is shown in Figure 4­3b. The ohmmeter circuits are protected for voltages
applied to the "Ω (f’)" input up to 350 V peak. Large
negative voltages are blocked by CR12. Large positive
voltages are blocked by the high collector to base
breakdown voltages of Q13 and Q14. CR13 conducts
for positive voltages greater than approximately 2 V,
causing CR14 to conduct.

Figure 4-3. Ohms Converter.

4-2

Model 34702A TM 11-6625-2809-14 & P

turning on Q12. This places - 12 V at the collector of
Q12 which turns off transistors QI 1, Q13, and Q14.

419. AC Measuring Circuits.

420. A simplified diagram of the circuits used to
measure ac voltage is shown in Figure 4-4.

The attenuation of the input signal by the Attenuator
for the four ac voltage ranges is:

Range Attenuation Factor

1V X 1

1OV X 0.1

100V X 0.01

1000V X 0.001

The output voltage of the attenuator is buffered by the
Impedance Converter. The voltage gain of the
Impedance Converter is adjustable and is appr oximately
one. Its input impedance is very high to minimize loading
of the Attenuator and its output resistance is low to drive
the Converter Amplifier. T he AC Converter yields a dc
output voltage that is proportional to the average value of
the negative half-wave rectified input signal. The
resulting voltage is filtered and m easured by the Display
Module.

4-21. Impedance Converter. A simplified diagram of
the Impedance Converter is shown in Figure 4-5. The
input transistor Q1 is a sourc e follower. Transistors Q2
and Q3 constitute an amplifier that provides bias c urrent
to Q1 and a high input resistance (load resistance) for
Q1. A positive going voltage at point 1 causes the
voltage at point 2 to increase. This incr eased voltage at
point 2 increases the

Figure 4-4. Ac/DC Converter.

4-3

Model 34702A TM 11-6625-2809-14 & P

current through Q2. The increased current causes the
voltage at point 4 to increase. Since Q3 is an emitter
follower, point 3 will also increase and follow very closely
the voltage at point 2. Since the output voltage is taken
at the emitter of Q3, RI3 m ay be increased to make the
gain of the amplifier greater than unity.

4-22. AC Converter. Refer to Figure 4-4 for the
following discussion. Overall ac feedback is supplied
from point 5 back to the inverting input. The voltage at
point 5 is similar in shape to the voltage at point 2,
inverted and about one-half the amplitude. Current for
the negative half of the waveform at point 5 flows
through CR8, R31 and R33. Current for the positive half
of this waveform f lows through CR9, R32 and R33. The
output voltage is taken at the cathode of CR9, filtered by
the Low Pass Filter and measured by the Display
Module. The DC Feedback Amplifier provides a low
frequency feedback path around the Converter Amplifier
to keep the Converter Amplifier biased properly.

Figure 4-5. Impedance Converter.

4-4

WARNING

These servicing instructions are for use by qualified personnel
only. To avoid electrical shock, do not perform any servicing
other than that contained in the operating instructions unless
you are qualified to do so.

5-0

TM 11-6625-2809-14 & P

Model 34702A TM 11-6625-2809-14 & P

SECTION V.

MAINTENANCE

5-1. INTRODUCTION.

5-2. This section contains information necessary for
maintenance of the -hp- Model 34702A Multimeter.
Included are Performance Tests and Adjustment
Procedures for the 30 day, 90 day, 6 month, and I year
intervals referred to in Table 1-1. To determine the
optimum calibration interval for your instrument, refer to
MIL Specification MILC-45662A. If, after completing the
Performance Checks, you find that the instrument does
not meet its required specifications, refer to the
Adjustment Procedure (Paragraph 5-16). Attempt to
readjust the instrument to bring it into specification. If,
after adjusting the instrument, it is still out of
specification, refer to troubleshooting in Section VII.

5-3. RECOMMENDED TEST EQUIPMENT.

5-4. The test equipment that is recommended for
maintaining the Model 34702A is listed in Table 5-1. If
the recommended model is not available, use equipment
that has specifications equal to or better than those
listed.

5-5. PERFORMANCE TESTS.

5-6. The following tests verify that the Model 34702A
is operating properly and meets the specifications listed
in Table 1-1 of this manual. These tests should be
completed before any attempt is made to adjust the
instrument.

5-7. A Performance Test Record is provided at the
end of this section for recording the results of the
Performance Tests.

5-8. All of the following tests have been written to
include the use of either a 34740A or 34750A Display
Module.

Table 5-1. Recommended Test Equipment.

Instrument

Type

AC Calibrator 1 V, 10 V, 100 V

100 Ω, 1ΚΩ
10ΚΩ, 100ΚΩ
1ΜΩ, 10ΜΩ
standard resistors
DC Standard 1 V, 10 V, 100 V,

Electronic
Counter

Required

Characteristics

1000 V, 45 Hz to
100 kHz
Accuracy: +0.04%
of setting (45 Hz to
20 kHz)
+ 0.15% of setting
(100 kHz)
Accuracy: +0.01%

1000 V Ranges
Accuracy: +0.008%
Capable of measur­ing the period of
50 Hz or 60 Hz to
within + .01%

Recommended

-hp- Model
745A/746A

General Radio
Model GR 1433-Z
Decade Resistor

-hp- 740B

-hp- Model 5300A/
5302A

34750A

Accuracy (+ 23

o

C + 5oC), <95% RH):

30 days +(0.025% of reading + .005% of range)
90 days ±(0.035% of reading + .005% of range)

6 mo. ±(0.045% of reading + .007% of range)

1 yr. ±(0.06% of reading + .01% of range)
RECOMMENDED TEST EQUIPMENT:
DC Standard, -hp- Model 740B
TEST PROCEDURE:

Model

5-9. DC Accuracy Test (DCV Function).

DESCRIPTION:
This test verifies the ability of the Model 34702A to
measure dc voltage accurately within the specification
limits.
SPECIFICATION.
34740A

Accuracy (+ 23o C + 5o C), < 95% RH):

30 days + (0.03% of reading + .01% of range)
90 days + (0.04% of reading + .01% of range)
6 mo. + (0.05% of reading + .02% of range)

1 yr .+ (0.06% of reading + .02% of range)

a. Select the DCV function of the Model 34702A
and connect a dc standard (-hp- Model 740B or
equivalent) to the 34702A INPUT V terminals.

b. Check dc accuracy for both polarities of input
according to Table 5-2. Apply short to 34702A input to
check 0 V reading on all ranges.

NOTE

With 1000 V applied only the positive
polarity is checked due to the possibility
of arcing within the Model 740B.

Rev. B 5-1

Model 34702A PERFORMANCE TEST TM 11-6625-2809-14 & P

Table 5-2. DC Accuracy.

5-10. Input Impedance Test (DCV and ACV

Function).

DESCRIPTION:
Input impedance affects the ability of a voltmeter to

accurately measure a given voltage because of loading
effects caus ed by the impedance Nor mally, it is desirable
to achieve as high an input impedance as pos sible. T his
check ensures that the input Impedance of the Model
34702A meets the specifications listed below.

SPECIFIC ATION:

Input Resistance

1 and 10 V ranges: 11.11 ΜΩ + 0.2% <
100 V range: 10.1 ΜΩ + 0.2% <80 pF
1000 V range: 10 ΜΩ ± 0.2% < 80 pF

RECOMMENDED TEST EQUIPMENT:
AC Calibrator, -hp- Model 745A

DC Standard, -hp- Model 740B
Resistance Decade, GR Model 1433-Z

TEST PROCEDURE:

a. Connect the equipment as shown ill Figure 5-1.
The Model 34702A should be set to DCV on the 1 V
range.

80 pF

Rev. B 5-2

b. Set the resistance decade to 10 ΜΩ and then

shunt it with a jumper lead. Set the DC standard for +

1.0000 V (34740A Display) or + 1.00000 V (34750A
Display) as observed on the Display Module.

c. Remove the jumper lead and again observe the
display. It should read between .5258V and .5268V
(34740A) or between .52582 and .52681 (34750A).

NOTE

The 34702A is not checked on the 10 V
range since the input circuit is equiv alent
for both the 1 V and the 10 V ranges.

d. Set the Model 34702A to the 100 V range and
short the resistance box with a jumper lead.

e. Set the dc standard for + 100.00 V (34740A) or
+ 100.000 V (34750A) as observed on the Display
Module.

WARNING

Use extreme cauti

on

when removing or
replacing the jumper in Steps f, g and i
to avoid electrical shock when
performing the input impedance test on
the 100 V’ and 1000 V ranges.

Model 34702A PERFORMANCE TEST

Figure 5-1. Input Impedence Test.

f. Turn the dc standard OUTPUT to OFF.
Remove the jumper from the resistance box. Set dc
standard OUTPUT to ON and again observe the display.
It should read 50.20 to 50.30 (34740A) or 50.201 to

50.301 (34750A).

The 34702A display should indicate >.7059 (34740A) or>
.70594 (34750A). This verifies the 34702A input
capacity specification.

TM 11-6625-2809-14 & P

I. Change the ac standard fr equency to 20 kHz.

g. Turn the dc standard OUTPUT to OFF. Set
the Model 34702A to the 1000 V range and short the
resistance box with a jumper lead.

h. Turn the dc standard OUTPUT to ON. Set
the dc standard for + 1000.0 V (34740A) or + 1000.00
V (34750A) as observed on the Display Module.

i. Turn the dc standard OUTPUT to OFF.
Remove the jumper from the resistance box. Turn the
dc standard OUTPUT to ON and again observe the
display. It should read 499.7 to 500.7 (34740A) or

499.75 to 500.75 (34750A).

j. Set the dc standard OUTPUT to zero.
Replace dc standard with the ac standard.

k. Set the Model 34702A to the 1 V range.
Replace the resistance box with a 100 κΩ resistor (-hp­Part Number 0757-0465). Connect one end of the
resistor directly to the HI terminal. Set the ac s tandard
frequency to I kHz. Adjust the ac standar d am plitude for
+ 1.0000 V i 1 count(34740A) or + 1.00000 V + 1 c ount
(34750A) as observed on the Display Module.

5-1. DC Effective Common Mode Rejection.

DESCRIPTION:
Effective Common Mode Rejection (ECMR) is a

measure of the eff ect of a com mon mode s ource on the
measured value or readout of the instrument with a
1kohm unbalance. Typically ECMR is measured in
decibels (dB) and can be calculated by the following
formula:

Common Mode Voltage Applied

ECMR (dB) = 20 log10 (

________________________________________

Change in Display Indication

SPECIFICATION
:
Effective Common Mode Rejection (I

κΩ

unbalance): > 80 dB.
RECOMMENDED TEST EQUIPMENT:

DC Standard, -hp- Model 740B
Resistor, I κΩ t 1% (resistance decade may be used for
this)

)

Figure 5-2. Effective Common Mode Rejection

Rev. C 5-3

Model 34702A PERFORMANCE TEST TM 11-6625-2809-14 & P

TEST PROCEDURE

a. Disconnect all previous connections to the

Model 34702A input and connect the equipment as

-2.

shown in Figure 5

Set the dc standard for a +10 V

output. Set the 34702A to the I V range.

b. Observe the voltmeter display. It should read
less than 10 counts (34740A Display) or 100 counts
(34750A Display). This verifies an effective common
mode rejection at dc of > 80 dB.

5-12. Normal Mode Rejection.

DESCRIPTION:
Normal Mode Rejection (NMR) is a measure of the ability
of the Model 34702A to reject ac signals applied to the
INPUT V terminals while the instrument is operating in
DCV function. NMR is measured in decibels (dB) and
can be calculated by the following formula:

Peak Normal Mode Voltage

____________________________________

NMR (dB) = 20 log

(

10

)

Peak Display Indication
SPECIFICATION:
Normal Mode Rejection: Greater than 60 dB (at 50 Hz

t 0.1%or 60 Hz ± 0.1%).
RECOMMENDED TEST EQUIPMENT:
AC Calibrator, -hp- Model 745A

Electronic Counter, -hp- Model 5300A/5302A
TEST PROCEDURE:

a. Disconnect all previous connections to the

34702A input and connect the equipment as
shown in Figure 5-3. Set the Model 34702A to
DCV and the 1 V range.

b. Adjust the ac calibrator output for .707 V rms (1V

peak).

c. Set the counter controls to meas ure period and
adjust the ac calibrator frequenc y for a counter indic ation
between 16.650 ms and 16.683 ms (19.980 ms to

20.020 ms for Option 050). The Display Module should
read <10 counts (34740A Display) or <100 counts
(34750A Display).

5-13. AC Accuracy.

DESCRIPTION:
This test verifies the ability of the Model 34702A to
measure ac voltage accurately to within the specification
tolerances.

SPECIFICATION:
34740A

Accuracy (+ 23°C ± 5°C, <95% RH)'

30 days

45 Hz to 20 kHz +(0.25% of reading +

.05% of range)

5%

20 kHz to 100 kHz +(0.7

of reading +

.05% of range)

90 days

45 Hz to 20 kHz +(0.30°c of reading +

.05% of range)

20 kHz to 100 kHz +(0.80% of reading +

.

05% of range)

6 mo.

45 Hz to 20 kHz +(0.35% of reading +

.05% of range)

20 kHz to 100 kHz +(0.85% of reading +

.05% of range)

I yr.

45 Hz to 20 kHz +(0.50% of reading +

0.05% of range)

20 kHz to 100 kHz +(1.0% of reading +

0.05% of range)

Figure 5-3. Normal Mode Rejection.

Rev. A 5-4

Model 34702A PERFORMANCE TEST TM 11-6625-2809-14 & P

34750A

Accuracy (+ 23

30 days

45 Hz to 20 kHz +(0.25% of reading +
20 kHz to 100 kHz +(.75% of reading +

90 days

45 Hz to 20 kHz ±(.3% of reading +
20 kHz to 100 kHz +(.8% of reading +

6 mo.

45 Hz to 20 kHz +(.35% of reading +
20 kHz to 100 kHz +(.85% of reading +

1 yr.

45 Hz to 20 kHz ±(0.50% of reading +
20 kHz to 100 kHz ±(1.0% of reading +

o

C + 5°C, < 95% RH):

.05% of range)
.05% of range)

.05% of range)
.05% of range)

.05% of range)
.05% of range)

0.05% of range)

0.05% of range)

AC Calibrator/High Voltage Amplifier, -hp- Model
745A/746A or equivalent.

TEST PROCEDURE:

a. Set the Model 34702A function switch to ACV
and select the I V range. Apply short to 34702A input
and check 0 V reading on all ranges.

b. Using an ac calibrator and a high voltage
amplifier (-hp- Model

745A/746A

recommended), check
the accuracy of the Model 34702A for inputs other than 0
V at 45 Hz and 20 kHz using Table 5-3(a). Also check
the accuracy for these inputs at 100 kHz using Table 5­3(b). All readings should be within the limits specified by
the tables.

514. Response Time.

DESCRIPTION:
This test verifies the ability of the Model 34702A to

respond quickly to changes in input voltage.

SPECIFICATION:
34740A

RECOMMENDED TEST EQUIPMENT:

Response time: < 2 s to within + 0.3% of final value or 20
counts, whichever is greater.

Table 5-3. (a). AC Accuracy (45Hz and 20 kHz).

Rev. B 5-5

Model 34702A PERFORMANCE TEST TM 11-6625-2809-14 & P

Table 5-3(b). AC Accuracy (100 kHz).

34750A
Response time: <2 s to within t 0.3% of final value or 200

counts, whichever is greater.
RECOMMENDED TEST EQUIPMENT:

AC Calibrator, -hp- Model 745A or equivalent
TEST PROCEDURE:

a. Set the ac calibrator output to 10 V at I k Hz. Set

the 34702A to ACV on the 10 V range.

b. Connect the output of the ac calibrator to the
34702A INPUT V terminals while observing the
34740A/34750A Display Module. The display indication
should read within 30 counts (34740A) or 300 counts
(34750A) of its final value within two seconds after the
34702A is connected to the ac calibrator.

5-15. Ohms Accuracy.

DESCRIPTION:
This test verifies the ability of the Model 34702A to

accurately measure resistance to within the limits of the
specification given below.
SPECIFICATION:

34740A

Accuracy (+ 23

o

C + 5°C, < 95% RH):

Rev. A 5-6

30 days

90 days

6 mo.

1 yr.

34750A

Accuracy (+ 23

30 days

10 ΜΩ range +(0.25% of reading +

0.02% of range)
All other +(0.05% of reading +
ranges 0.02% of range)

10 ΜΩ range +(0.30% of reading +

0.02% of range)
All other +(0.06% of reading +
ranges 0.02% of range)

10 ΜΩ range +(0.35% of reading +

0.03% of range)
All other ±(0.07% of reading +
ranges 0.03% of range)

10 ΜΩ range +(0.50% of reading +

0.03% of range)
All other +(0.1 1% of reading +
ranges 0.03% of range)

o

C + 5°C, <95% RH):

10 ΜΩ range +(0.25% of reading +

0.015% of range)
All other +(0.045% of reading +
ranges 0.015% of range)

Model 34702A PERFORMANCE TEST TM 11-6625-2809-14 & P

90 days

10 ΜΩ range +(0.3% of reading +

0.015% of range)

All other ±(0.055% of reading +

ranges 0.015% of range)

6 mo.

10 ΜΩ range +(0.35% of reading +

0.02% of range)
All other +(0.065% of reading +
ranges 0.02% of range)

1 yr.

10 ΜΩ range ±(0.50% of reading +

0.02% of range)
All other +(0.1 1% of reading +
ranges 0.02% of range)

RECOMMENDED TEST EQUIPMENT:

Resistance Decade, GR Model 1433-Z or equivalent.

Due to temperature change inside the
instrument between line and battery
operation, the voltage references in the
Display Module must be adjusted when
changing modes to achieve these
specifications.

TEST PROCEDURE:

a. Connect a resistance decade with 100 f through

ΜΩ

steps to the INPUT i2 terminals of the Model

34702A.

b. Refer to Table 5-4 and check the accuracy of the

34702A on the 100 Ω through 10 ΜΩ ranges.

Table 5-4. Ohms Accuracy Test.

NOTE

5-7