Fluke 732a User manual

NOTE
This manual documents the Model 732A and its assemblies at the revision levels shovwn in
Appendix 7A. If your instrument contains assemblies with different revision letters, it will
be necessary for you to either update or backdate this manual. Refer to the supplemental
change/errata sheet for newer assemblies, or to the backdating sheet In Appendix 7Afor
older assemblies.
For the benefit and convenience of its customers, Fluke
Corporation (Fluke) has reproduced this copy of amanual
which is no longer in production. This manual has not been
edited or updated since the revision date shown on the lower
left fiend corner of the ^rst pege. Fluke will not be liable for
any claims, losses or damages of any kind incurred by any
user arising from use of this manual.
732A
DC Reference
Standard
Instruction Manua
IFLUKE
P/N 645051
MAY 1983
«19S3, John Fluke Mfg. Co., Inc., all rights reserved. LUho in U.S.A.

732A
Table of Contents
SECTION TITLE PAGE
1INTRODUCTION AND SPECIFICATIONS 1-1
l-l. INTRODUCTION l-l
1-
8. SPECIFICATIONS M
2OPERATION 2-1
2-
1. INTRODUCTION 2-1
2-3. SHIPPING INFORMATION 2-1
2-7. INSTALLATION 2-1
2-9. FRONT AND REAR PANEL FEATURES 2-1
2-11. OPERATING NOTES 2-1
2-12. Introduction 2-1
2-14. Input Power Requirements 2-1
2-16. AC Line Voltage Selection 2-1
2-18. Fuse Replacement 2-1
2-20. Backup Operating Power 2-5
2-22. Battery Charging 2-5
2-25. IN CAL Indicator and RESET Terminal 2-5
2-27. Portability 2-5
2-29. Guarded Operation 2-5
2-33. Oven Temperature Thermistor 2-6
2-36. Minimizing Error Sources 2-6
2-
45. OPERATION 2-7
3THEORY OF OPERATION 3-1
3-
1INTRODUCTION 3-1
3-3. OVERALL FUNCTIONAL DESCRIPTION 3-1
3-8. CIRCUIT DESCRIPTION 3-1
3-10. Power Supply (A3 and A4) 3-1
3-14. Voltage Monitor 3-1
3-17. Reference Circuit, A5 3-2
3-20. Output Divider 3-2
3-22. Oven Controller .3-2
3-
25. Battery Charger 3-2
4MAINTENANCE 4-1
4-
1. INTRODUCTION 4-1
4-5. SERVICE INFORMATION 4-1
4-8. GENERAL MAINTENANCE 4-1
(continued on page it)

732A
TABLE OF CONTENTS, continued
SECTION TITLE PAGE
4-9. Access Procedure 4-i
4-19. Oven Disassembly ;.4-6
4-21. Front Panel Removal 4-6
4-23. Cleaning 4-6
4-26. Fuse Replacement 4-6
4-28. AC Line Voltage Change 4-6
4-30. ACCEPTANCE TEST 4-8
4-32. CALIBRATION 4-8
4-35. Null Verification 4-8
4-37. Procedure A; Calibrate to Certified 732A 4-9
4-39. Procedure B: Calibration to Standard Cells 4-10
4-41, SERVICE/ REPAIR PROCEDURES 4-14
4-42. Introduction 4-14
4-44. Battery Charger Adjustment Procedure 4-14
4-46. TROUBLESHOOTING 4-14
4-47. Introduction 4-14
4-49. External Symptom Troubleshooting 4-16
4-51. Internal Voltage Measurements 4-16
4-53. Oven Repair 4-16
5LIST OF REPLACEABLE PARTS 5-1
TABLE OF CONTENTS 5-1
6ACCESSORIES 6-1
INTRODUCTION 6-1
6-3. DUAL MOUNTING FASTENERS (MOO-800-5237) 6-1
6-5. HALF-WIDTH RACK MOUNT KIT (M07-203-601) 6-1
6-7. FULL-WIDTH RACK MOUNT KIT (M07-200-603) 6-1
6-9. LOW THERMAL EMF CABLE ASSEMBLY (5440A-7002) 6-1
6-11. BATTERY PACK (732A-7001) 6-1
6-13. TRANSIT CASE (732A-7002) 6-1
7GENERAL INFORMATION M
7A MANUAL CHANGE INFORMATION 7A-1
8SCHEMATIC DIAGRAMS 8-1
TABLE OF CONTENTS 8-1
INDEX 8-12
//

List of Tables
TABLE TITLE PAGE
i-I. 732A Accessories ]»}
1-
2, 732A Specificiations U2
2-
1, Front Panel Features 2-4
2-2. Rear Panel Features 2-4
4-1. Test Equipment Required 4-2
4-2. External System Troubleshooting 4-17
4-3, Internal Measurements *4-18

List of Illustrations
FIGURE TITLE PAGE
Frontispiece 732A DC Reference Standard vi
1-
1. 732A Outside Dimensions 1-4
2-
1. Front Panel Features 2-2
2-2. Rear Panel Features 2-3
2-3. Guard Connections 2-6
2-
4. 732A/ Precision Divider, Providing AStable, Adjustable Source 2-8
3-
1. Functional Block Diagram 3-3
4-
1. Cover and Front Panel Screw Locations 4-3
4-2. Rear Module Mounting Screw Locations 4-3
4-3. Regulator PCB Assembly Removal 4-4
4-4. Oven Assembly Removal 4-5
4-5. AC Line Voltage Conversion on A3 Pre-Regulator PCB Assembly 4-7
4-6. 732A lOV Calibration 4-16
4-7. Calibration of Point Ato lOV Using 732A 4-10
4-8. Calibration of 1.081V (and IV) to 732A 4-10
4-9. 732A lOV Calibration Using Standard Cells 4-12
4-10. 732AProcedure ‘B’ lOV Calibration 4-13
4-1 1. Calibration of 1.081V (and IV) to 732A Procedure ‘B’ 4-13
4-12. Battery Charger Test Points and Adjustments on
A3 Pre-Regulator PCB Assembly 4-15

732A DC Reference Standard

732A
Section 1
Introduction and Specifications
1-1. INTRODUCTION
1-2. The Fluke Model 732A is ahighly stable, rugged,
and transportable, solid stale, dc voltage reference
standard. The 732A has lOV, 1.018V and IV outputs.
These outputs are available on front panel binding posts.
The calibration adjustments for the lOV, L018V and IV
outputs are accessible through the front panel. Anon-
conducting adjustment tool is supplied with the unit for
this purpose.
1-3 .All outputs of the 732Acan be shorted indefinitely
without damage. Recovery occurs in less than 2minutes
after the short is removed, with no loss of stability.
I“4. The stability and accuracy of the 732A allow direct
substitution for saturated standard cells in many
applications. The stability specification of 0.5 ppm for 30
days is achieved by enclosing the reference amplifier and
output divider of the 732A in ahigh thermal gain oven.
Full accuracy is attained over the specified ambient
temperature range of 23 ±5^C (64.4 to 82.4"^ F).
Variations in oven temperature may be monitored
externally via the OVEN TEMP THERMISTOR
terminals on the front panel.
I“5. The 732 Amay be powered from ac line power, an
internal rechargeable battery, or an external low voltage
ac or dc source. The 732A is designed to be powered
continuously, including during storage or shipment. The
back-up battery will continue to operate the 732A for up
to 12 hours. Either line or battery power may be removed
without affecting the output. The battery is kept charged
by an internal battery charger when operating from ac
line power, or from the external low' voltage ac or dc
source.
1«6, Various front panel LEDs (indicators) provide a
continuous indication of the operating status of the 732A.
The AC PWR indicator illuminates in the presence of ac
line power. The BTRY CHG indicator is on steadily for
normal charging activity, and is off when the battery is
charged. The IN CAL indicator monitors the input
voltage to the Reference and Oven. Should this voltage
fall below that needed to keep the 732A operational, the
IN CAL indicator is latched off, indicating aloss of power
and standardization. Once power is restored and
standardization has been verified, the IN CAL indicator
can be reset.
1-7. The 732A may be used on the bench or rack
mounted. The 732A is ahalf-rack width instrument and
occupies 4standard 1.75 inch rack spaces. Accessories for
the 732A are listed in Table 1-1 and described in more
detail in Section 6of this manual There are no options
available for the 732A.
1-8* SPECIFICATIONS
I-9. Table I-2 lists the specifications for the 732A.
Table 1-1. Accessories
MODEL
NUMBER DESCRIPTION
MOO-800-523
M07-203-601
M07-200-601
5440A-7002
732A-7001
732A-7002
732A-7003
Dual Mounting Fastener
Half Width Rack Mount Kit
Full Width Rack Mount Kit
Low Thermal EMF Cable Assembly
Battery Pack
Transit Case
Battery Charger
1-1

732A
Table 1-2. 732A Specifications
OUTPUT VOLTAGE 10 volts. 1.018 volts, or 1volt
TRANSFER UNCERTAINTY @18“C to 28°C
Output Voltage Time Interval
30 Days 90 Days 6Months 1Year
10V 0.5 ppm 1.5 ppm 3.0 ppm 6.0 ppm
1.018V 1,5 ppm 4.0 ppm 8.0 ppm 12.0 ppm
1V 1.5 ppm 4.0 ppm 8.0 ppm 12.0 ppm
These specifications assume the unit has been continuously powered up with either ac or battery or both. The
specifications include effects due to line regulation.
TEMPERATURE COEFFICIENT OF OUTPUT
Range Temperature Coefficient (ppm/^C)
OX to 18X 28°C to AO^C
10V ±0.05 ±0.05
1.018V ±1.0 ±1.0
1V ±1,0 ±1.0
OUTPUT ADJUSTMENT AND RESOLUTION
Output Adj. Range AdJ. Resolution
10V ±50a/V <0.05 ppm
1.018V ±50 //V <0.25 ppm
1.0V ±5 /iV <0.10 ppm
OUTPUT IMPEDANCE
10V <5 milliohms
1.018V, IV «1 kilohm
OUTPUT CURRENT
10V 12 mA maximum
1.018V, IV Current limited by Ik Osource impedance
OUTPUT PROTECTION The output may be shorted indefinitely without damage to the
instrument. The instrument is protected against high voltage up to
1000V provided that the net current into the 732A does not exceed
30 mA.
OUTPUT NOISE ^1 A<V RMS at 10V output, 0.1-10 Hz.
LOAD REGULATION AT
0.12 mA OUTPUT CURRENT <6.0 ppm
LINE REGULATION <0.05 ppm of output for full ±10% power line variation.
LINE POWER REQUIREMENTS
Nominal Setting Voltage Limits Fuse
100V 90- 110V 0.375A/250V SLO-BLO
120V 108- 132V 0.375A/250V SLO-BLO
220V 198-242
V
0.250A/250V slO-BLO
240V 216-264V 0.250A/250V SLO-BLO
1-2

732A
1*2. 732A Specifications (cont)
Condition Temperature o/o Relative Humidity
(»C) (Non-condensing)
Non-operating -40 to +50 Not Controlled
Oto 50 95 ±5%
Operating Oto 30 95 ±5%
30 to 40 7±5%
VIBRATION
Frequency GForce Frequency Double AmpHlude
5-55 Hz 2@55 Hz 0.013 inch
1-3

732A
V4

static awareness
AMessage From
John Fluke Mfg. Co., Inc.
Some semiconductors and custom IC’s can be
damaged by electrostatic discharge during
handling. This notice explains how you can
minimize the chances of destroying such devices
by;
1. Knowing that there is aproblem.
2. Learning the guidelines for handling them.
3. Using the procedures, and packaging and
bench techniques that are recommended.
The Static Sensitive (S.S.) devices are identified in the Fluke technical manual parts list with the symbol
“(S>
The following practices should be followed to minimize damage to S.S. devices.
1. MINIMIZE HANDLING
2. KEEP PARTS IN ORIGINAL CONTAINERS
UNTIL READY FOR USE.
3. DISCHARGE PERSONAL STATIC
BEFORE HANDLING DEVICES
4. HANDLE S.S. DEVICES BY THE BODY
Page 1of 2

5. USE ANTI-STATIC CONTAINERS FOR
HANDLING AND TRANSPORT
WHEN REMOVING PLUG-IN ASSEMBLIES,
HANDLE ONLY BY NON-CONDUCTIVE
EDGES AND NEVER TOUCH OPEN EDGE
CONNECTOR EXCEPT AT STATIC-FREE
WORK STATION. PLACING SHORTING
STRIPS ON EDGE CONNECTOR USUALLY
PROVIDES COMPLETE PROTECTION TO
INSTALLED SS DEVICES.
AVOID PLASTIC. VINYL AND STYROFOAM®
IN WORK AREA
PORTIONS REPRINTED
WITH PERMISSION FROM TEKTRONIX, INC.
AND GENERAL DYNAMICS, POMONA DIV.
•Dow Chemical
10. ONLY ANTI-STATIC TYPE SOLDER-
SUCKERS SHOULD BE USED.
11. ONLY GROUNDED TIP SOLDERING
IRONS SHOULD BE USED.
Anti-static bags, for storing S.S. devices or pcbs
with these devices on them, can be ordered from the
John Fluke Mfg. Co., Inc.. See section 5 in any Fluke
technical manual for ordering instructions. Use the
following part numbers when ordering these special
bags. ..^
John Fluke Part No.
680892
680934
680942
680983
681023
Pink Poiy Sheet
30" X60" X60 Mil
P/N RC-AS-1200
$20.00
Description
5" X8" Bag
8" X10" Bag
8" X12" Bag
12" X16" Bag
18" X18" Bag
Wrist Strap
P/N TL6-60
$7.00
Page 2of 2J0089C-07U8412/SE EN Litho in U.S.A.

732A
Section 2
Operation
2-1. INTRODUCTION
2-2. The information in this section describes the
installation and operation of the Model 732A, It is
recommended that the contents of this section be read and
understood before any attempt is made to operate the
instrument. Should any difficulties arise during
operation, contact your nearest John Fluke Sales
Representative, or the factory. Our mailing address is:
John Fluke Mfg, Co., Inc.;P.O. Box C9090;Everett, WA
98206 (206) 347-^100
2-3. SHIPPING INFORMATION
2“4. The 732A is packaged and shipped in afoam-
packed container. Upon receipt of the instrument, a
thorough physical and electrical inspection should be
made to reveal any possible shipping damage. Special
instructions for inspection and claims are included on the
shipping carton.
2-5. If reshipment of the instrument is necessary, the
original container or equivalent should be used.
2-6. If the instrument is to be shipped with battery
power on, use the Transit Case accessory described in
Section 6. Alternatively, 24V to 40V dc or 24V to 30V ac
may be applied, via the rear panel connectors, to supply
power during shipment.
2-7. INSTALLATION
2-8. The 732A is designed for convenient operation as
either abench or arack-mount instrument. Rack
mounting accessories available for use with the 732A are
described in Section 6.
2-9. FRONT AND REAR PANEL FEATURES
2-iO. The Front and Rear panels are shown in Figures
2-i and 2-2. The various controls and connections are
listed and explained in Tables 2-1 and 2-2.
2-11. OPERATING NOTES
2-12, Introduction
2-13. The following paragraphs describe various
conditions that should be considered before operating the
732A. If the 732A is brand new, set the rear panel
BATTERY OPR switch to ON and perform the
acceptance test described in Section 4of this manual
2-14. Input Power Requirements
2-1 5. The 732A is designed to be powered continuously
(including storage or shipment) to maintain
standardization. Normally, power is continuously
applied, either to the ac line input connector or to the low
voltage ac or dc input connectors. The ac line power
requirements are: lOOV, 120V, 220V or 240V ac± 10%, at
50 or 60 Hz. Low voltage, 24-40V dc or 24-30V ac, 50-400
Hz may be connected to supply instrument power and
charge the internal backup battery through connectors on
the rear panel. The internal, rechargeable gell-cell (sealed,
gelled electrolyte lead-acid) battery provides
approximately 12 hours of continuous operation when ac
power is not available.
2-16. AC Line Voltage Selection
2-17. The Line Voltge Selector switches are located
inside the instrument. Their setting is marked on the rear
panel (See Figure 2-2). If the marked setting does not
agree w'ith the locally available ac power, the settings of
the internal Line Voltage Selector switches must be
changed. Refer this and all servicing to qualified
personnel. The procedure is described in Section 4,
2-18. Fuse Replacement
2-19. The ac line fuse is located on the rear panel of the
instrument. If the fuse requires replacement, replace it
w'ith one appropriate for the ac line voltage indicated on
the rear panel For ac line voltages from iOOV to 120V use
a3/ 8
A
Siow-Blow fuse. Forac line voltages from 220V to
240V use aI/4A Slow-Blow fuse.
2-1

732A
Figure 2>1. Front Panel Features
2-2

732A
Figure 2-2. Rear Panel Features
2-3

732A
Table 2-1, 732A Front Panel Controls and Adjustments
ITEM FEATURE NAME DESCRIPTION
11.018V Adjustment* Calibration tool adjustment. ±50 pV adjust for 1,018V output.
21V Adjustment* Calibration tool adjustment. ±5 adjust for IV output.
310V Adjustment* Calibration tool adjustment ±50 fj\/ adjust for 10V output.
4AC PWR Indicator LED that indicates the presence of ac power when illuminated.
5BTRY CHG Indicator LED that indicates battery charger operation when illuminated.
6IN CAL Indicator** LED that indicates out-of-calibration condition when not illuminated.
7RESET** Terminal behind front panel to reset the IN CAL indicator to ON condition.
8GUARD Terminal Binding post that connects to internal Guard circuit. Normally connected
to OUTPUT LO at some point in the measurement system. 60V is the
maximum differential allowed between GUARD and CHASSIS GROUND.
9CHASSIS GROUND Terminal Binding post connected to the chassis of the 732A.
10 IV HI Terminal Binding post on which the 1V output of 732A Is available.
11 LO Terminal Binding post which provides common connection for the 10V output.
12 LO Terminal Binding post which provides common connection for the IV and
1.018V outputs.
13 10V HI Terminal Binding post on which the 10V output of the 732A Is available.
14 1.018V HI Terminal Binding post on which the 1.018V output of the 732A is available.
15 OVEN TEMP THERMISTOR
terminals
3/4-inch spaced dual binding posts. Floating thermistor for monitoring
oven temperature.
*The 10V adjustment affects both the 1.018V and 1Voutputs. This adjustment should be made first when
calibrating the 732A. See Section 4.
“The IN CAL indicator detects an out-of-range condition within the power supply of the 732A. If not
illuminated, the 732A is not operating at its specified accuracy. Use the RESET terminal to restore the IN CAL
indicator after re-calibration. See Section 4.
Table 2-2. T32A Rear Panel Features and Controls
FEATURE NAME DESCRIPTION
1AC Module Rear panel module containing the A3, Pre-Regulator PCB Assembly.
2Battery Module Rear panel module containing the A6A1, Battery PCB Assembly.
3SUPPLY SETTING
(Ac power requirements)
Specifies the correct ac line voltage required to operate the instrument.
4^chassis terminal Binding post that provides adirect chassis connection.
5BATTERY OPR switch Slide switch that sets instrument back-up battery supply, on or off.
6POWER INPUT jacks Dual %-inch spaced banana jacks for connecting an external power
source (24-40V dc or 24-30V ac, 50-440 Hz). The internal back-up battery
voltage may also be measured at these jacks.
2-4

732A
Table 2“2. Rear Panel Features (cont)
ITEM FEATURE NAME DESCRIPTION
7Fuse holder AC line fuse holder.
8Power connector lEC 3-wire receptacle, for ac line power connection. See item 3for
specified ac line voltage.
2-20, Backup Operating Power
2-2\, If ac line power fails or drops more than 30%
below the nominal value, the internal battery
automatically maintains operation. Set the rear panel
BATTERY OPR switch to on to enable the internal
battery* When line power fails, the AC PWR indicator
goes out, but the IN CAL indicator remains on* The unit
will continue to operate normally, until the battery
discharges* When the battery is discharged, the IN CAL
indicator will go out. When ac power is restored, the
BTRY CHG indicator illuminates, until the battery is
fully charged, The IN CAL indicator will not illuminate.
This indicates that the standardization of the instrument
must be reverified before the 732A is used. The battery
voltage may be measured at the POWER INPUT jacks
with ahigh impedance multimeter, such as Multimeter A,
Table 4-1.
2-22. Battery Charging
CAUTION
PERMANENT BATTERY DAMAGE WILL
RESULT IF THE BATTERY IS ALLOWED TO
DISCHARGE BELOW 19 VOLTS. THE
DEGREE OF DAMAGE IS AFUNCTION OF
THE DEPTH OF OVER-DISCHARGE AND
THE BATTERY TEMPERATURE.
2-23. Under normal operation, battery life should
exceed 5years. For best battery life, minimize the number
of charge/ discharge cycles and avoid deep (<19V)
discharge*
2-24, if the battery is fully discharged, 24 hours is
required to fully recharge the battery when operating the
732A from ac line power, if the battery is not fully
discharged, the charging time will be less, but always in
excess of the discharge time. When the battery is
charging, the BTRY CHRG indicator glows to indicate
charging activity and turns off when the battery is fully
charged.
2-25. IN CAL Indicator and RESET Terminal
2-26. If the IN CAL indicator does not illuminate (ac
power lost, battery dead or turned off), the output of the
732 Amay not meet the specifications listed in Section I.
The RESET terminal, located behind the front panel, is
used to restore the IN CAL indicator to the ON condition.
See Section 4for the reset procedures. Before resetting the
indicator, apply power (ac line or low voltage external ac
or dc), allow' astabilization period of 24 hours, then check
the 732A to insure that the various outputs are within
specification.
2-27. Portability
2-28. The 732A is portable and operational at ambient
temperatures between Oand 40''C (32 to 104"^ F). Norma!
handling and transportation will not alter accuracy or
stability if power is maintained by the internal battery or
through the externa! power connections. The instrument
may be used immediately after transportation, provided
that the IN CAL indicator is illuminated and that the
instrument has not been exposed to ambient
temperatures beyond the normal operating range (23 ±
5^C).
2-29. Guarded Operation
WARNING
LETHAL VOLTAGES MAY BE PRESENT
WHEN OPERATING THE 732A WITH THE
GUARD AND CHASSIS GROUND CON-
NECTIONS SEPARATED. AMAXIMUM
POTENTIAL DIFFERENCE OF 60V RMS MAY
APPEAR BETWEEN ANY COMBINATION OF
THE GUARD TERMINAL, CHASSIS
GROUND, REFERENCE STANDARD
OUTPUT, OR OVEN TEMPERATURE
THERMISTOR OUTPUT. IF THIS LIMITA-
TION IS EXCEEDED, DAMAGE TO THE
INSTRUMENT MAY RESULT.
2-30. The 732A is equipped with aguard that isolates
the internal circuitry from chassis and earth ground, A
GUARD terminal is provided on the front panel. When
properly used the guard can greatly reduce errors caused
by common mode voltages. In general, guarded operation
will be necessary under the following conditions:
1. When apotential exists between equipment
powder line grounds.
2. When long connection leads are used to
connect ahigh impedance load.
3. When operating the instrument in the presence
of high level radiated noise.
2-5

732A
2-31. Apotential difference may exist between the
power line grounds of the 732A and an instrument to
which it is connected. This potential difference can cause
circulating ground currents which cause errors in the
output voltage.
2-32. To prevent these errors the 732A GUARD
terminal should be connected to the load in such amanner
as to provide aseparate path for the circulating currents.
Connect the GUARD terminal to the grounded side of
the load, at the load. Figure 2-3 illustrates the correct
GUARD terminal connection and the rerouted ground
currents. The circulating current path may also be broken
by operating the 732A on battery power as described later
in this section.
2-33. Oven Temperature Thermistor
2-34. AThermistor, mounted inside the Oven Assembly
senses changes in the internal oven temperature. Use the
Oven Temperature Thermistor in conjunction woth an
external ohmmeter to monitor the temperature stability
of the oven vs time. The thermistor terminals are on to the
front pane! of the 732A. Both leads of the thermistor are
isolated from all parts of the 732A circuitry. Amaximum
potential difference of 60V is allowed between either of
the thermistor terminals and any other front panel
terminal (Guard, Ground, Reference Standard Outputs).
2-35. The nominal value of the Oven Temperature
Thermistor is between 3kQ and 4kQ at the normal oven
operating temperature. The thermistor has atemperature
coefficient of 3.8%/°C. The actual operating value is
shipped with the instrument.
2-36. Minimizing Error Sources
2-37. The inherent accuracy and stability of the 732A
may be easily degraded if the effects of thermal emf, lead
resistance and other factors are not considered and
minimized.
2-38. THERMAL ERRORS
2-39. When parts of acircuit operate at different
temperatures, thermal voltages will normally be present
at the equipment connections. These thermal voltages can
exceed 10 uV. Use the following techniques to minimize
thermal errors:
i. Use the Fluke 5440-7002 Low Thermal EMF
Interconnecting Cable Assembly .See Section 6,
Accessories.
CASE{CHASSIS)
WHERE:
R1 Cl =Leakage Resistance &Capacitance From Guard to Chassis
Ec =Potential Difference Between Power Line Grounds
Rq =732A Output Resistance
Rl =Load Resistance
Figure 2-3. Guard Connection
2-6

732A
2. Use #24 AWG or larger^ bare copper^ Teflon
insulated connecting wires. It is preferable to use
shielded, twisted pair cable. Avoid splices.
3. Avoid the use of ordinary, nickeUpiated,
banana plugs for equipment interconnections. Use
of iow' thermal emf spade lugs is recommended.
Crimp the lug onto the wire before soldering.
Loosen the top of the binding post, insert the lug
and tighten the binding post on the lug.
2-40. OTHER ERROR SOURCES
2-41. The effects of the finite (though very low) output
impedance of the 732A, the lead wire resistance and the
loading caused by the reference divider can not be
ignored. Use the following procedure to minimize the
effects of test lead resistance and output loading:
1.Connect the equipment as shown in Figure 2-4.
2. Calibrate the 732A/ Reference Divider
combination at the divider input terminals.
3. When calibration is complete, treat the 732A
and the Reference Divider as asystem.
4. Do not disconnect the Reference Divider at any
time, even if it is not required in agiven procedure.
Since the 732A/ Reference Divider system was
calibrated at the divider input terminals,
disconnecting it will change the loading on the
732A, and affect the calibration.
2-42. LONG TERM STABILITY
2-43. The user can determine the long term stability of
the 732A by tracking (recording) the output voltage
before and after each calibration. Over aperiod of time,
the tracked data should allow the user to compensate for
systematic errors in accuracy and precision. (Accuracy is
defined as the error between the 732A output and a
known standard. Precision is defined as the measure of
repeatability of the 732A output voltage in astatistical
sample).
2-44. When the user has compensated for all systematic
errors, only random errors should remain. The
uncertainty of measurements will then beafunction of the
random errors and user errors.
2-45. OPERATION
2-46. Use the following procedure to prepare the 732A
for initial operation.
1.Check the rear panel for ac power requirements
and connect the 732A power cord to an appropriate
power source.
2. Set the BATTERY OPR switch to ON.
3. Verify that the AC PWR indicator is
illuminated. The BTRY CHG indicator is also
illuminated if the batteries are not fully charged.
4. Allow the unit to stabilize for a period of 24
hours if either of the following apply:
a. The IN CAL indicator is not illuminated.
b. If the instrument has been stored in or
exposed to ambient temperatures in excess of the
normal operating range (23 ±5^C). Allow the
unit to stabilize for 24 hours.
5. Insure that the 732A is calibrated according to
the procedures described in Section 4.
6. The instrument is now ready for use.
7. If the IN CAL indicator goes out, the output of
the 732A is not standardized. Notify the Calibration
department or person(s) responsible for
maintaining the 732A. Refer to Section 4.
2-7

732A
NOTE
Use low thermal emf connections between the 732A and the precision divider input terminals.
CALIBRATION OR DIVIDED 0-10V OUTPUT.
Figure 2-4. 732A/PreelsIon Divider, Providing aStable, Adjustable Source
2-8