Keithley 172A User manual

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INSTRUCTION MANUAL
Digltal Multlmster
Models 172A. 173A
INSTRUCTION MANUAL
Digital Multimeter
MODELS 172A/173A
COPYRIGHT 1978, KEITHLEY INSTRUMENTS, INC.
PRINTEU APRIL, 1981, CLEVELAND, OHIO, U.S.A.
DOCUMENT NO. 29662, REV. B

CONTENTS
INSTRUCTION MANUAL
DigItal Mulllmrtw
Mod.1~ 17ZA. 173A
,ction
Page
INTENTS ......................................
.LuSTRATIoNs ...................................
GENERAL INFORMATION .............................. I-l
l-l. INTROOUCTION. .............................. 1-I
l-2. FEATURES ................................. l-1
l-3. WARRANTY INFORMATION. .......................... l-l
I-4.
CHANGE NOTICE .............................. I-I
l-5.
OPTIONAL MODEL 1728 RECHARGEABLE BATTERY PACK .............. l-1
1-6. OPTIONAL MODEL 1722 DIGITAL INTERFACE .................. I-I
1-7. OPTIONAL MODEL 1723 IEEE STANDARD 488 BUS INTERFACE ........... I-1
IECIFiCATIONS. .................................. I-'
INITIAL PREPARATION .............................. 2-l
2-1. GENERAL ................................ .2-l
2-2. INSPECTION. ............................... 2-l
2-3. PREPARATION FOR USE ........................... 2-I
OPERATING INSTRUCTIONS. ............................ 3-l
3-l. GENERAL .............................. ..3- 1
3-2. HOWTO SELECT POWER ........................... 3-l
;I;' HOWTO SELECT FUNCTION. ......................... 3-2
3-5: HOWTO SELECT RANGE ........................... 3-3
HOWTO MEASURE VOLTAGE. ......................... 3-4
3-6. HOWTO MEASURE CURRENT. (MODEL 172A ONLY) ................ 3-5
3-7. HOWTO MEASURE CURRENT. (MODEL 173A ONLY) ................ 3-6
3-8. HOW TO MEASURE RESISTANCE ........................ 3-7
3-9. FURTHER MEASUREMENT CONSIDERATIONS. ................... 3-8
3-10. HOWTO USE MODEL 172A/l73A OFF-GROUND .................. 3-11
3-11. HOWTO USE OPTIONAL PROBES AND SHUNTS .................. 3-12
3-12. HOWTO USE THE MODEL 1722 DIGITAL INTERFACE ............... 3-13
3-13. COMMENTS RELATIVE TO THE MODEL 172A/l73A SPECIFICATIONS ......... 3-25
3-14.
MODEL 1728 OPERATING Tips
. ACCESSORIES. .. ..... .................................................. if:;5
4-1. GENERAL..................................4- I
4-2. POWEROPTIONS .............................. 4-l
4-3. ISOLATED DIGITAL OUTPUT ......................... 4-1
4-4. RACK MOUNTING .............................. 4-i
4-5. PROBE AND SHUNTS. ............................ 4-4
4-6. CABLES AND CONNECTORS .......................... 4-5
4-7. MISCELLANEOUS .............................. 4-5
THEORY OF OPERATION .............................. 5-l
. 5-l. GENERAL.................................5- I
5-2. OVERALL OPERATION ............................ 5-l
5-3. INPUT SIGNAL CONDITIONING ........................ 5-l
5-4. A/O CONVERTER AND DIGITAL CIRCUITS (SCHEMATIC 29145E, SHEET 2). ..... 5-15
5-5. DISPLAY BOARD, SCHEMATIC 274040 ..................... S-21
5-6. POWER SUPPLY, SCHEMATIC 29145E. ..................... 5-21
MODEL 1728 RECHARGEABLE BATTERY PACK, SCHEMATIC 26758C. ......... 5-23
MODEL 1722 DIGITAL INTERFACE. ...................... 5-25
I
ii

INSTRUCTION MANUAL
Digital MultImeter
Models 172A. 173A
CONTENTS (CON'S)
iect ion
Page
;. MAINTENANCE.
6-i. GENERAL................................................................... ;I;
6-2. REQUIRED TEST EQUIPMENT. ........................ 6-l
PERFORMANCE VERIFICATION ........................ 6-l
CALIBRATION REQUIREMENTS ........................ 6-7
6-5.
PREPARATION FOR CALIBRATION. ...................... 6-8
6-6.
CALIBRATION PROCEDURE. ......................... 6-Y
6-7.
TROUBLESHOOTING AND REPAIR ....................... 6-15
6-8.
FUSE REPLACEMENT ............................ 6-21/Z
7. REPLACEABLE PARTS. .............................. 7-1
7-l. GENERAL.................................7- 1
7-2.
ORDERING INFORMATION .......................... 7-I
7-3.
FACTORY SERVICE. ............................ 7-l
7-4. REPLACEABLE PARTS LIST ......................... 7-l
CROSS REFERENCE OF MANUFACTURERS .................... 7-2
COVERS AND PANELS. ........................... 7-2
COMPONENT DESIGNATIONS FOR ~~-446. ................... 7-2
7-a. SCHEMATICS ............................... 7-2
7-Y.
COMPONENT LAYOUTS. ........................... 7-2
7-10.
SPARE PARTS KIT. ............................ 7-5
iii

INSTRUCTION MANUAL
Digital MuItlm*ter
Mod&172A.l73A
ILLUSTRATIONS
GURE NO. TITLE PAGE
1-l
l-2
l-3
l-4
2-l
2-2
2-3
;::
::i
;:;
3-7
3-a
3-9
3-10
3-11
3-12
4-l
4-2
5-l
::;
5-4
5-5
5-6
5-J
5-a
5-9
5-10
5-11
5-12
;:;;
:I;;
::g
6-l
6-2
J-1
Model l73A Front Panel ....................... 1-3
Bottom View Showing Line Cord. ................... l-4
Tilt Bail Positions. ........................ l-5
Dimensional Data .......................... 1-6
Rear Panel Showing Current Fuse. .................. 2-2
Model 1728 Rechargeable Battery Pack ................ 2-4
Installation of Battery Pack .................... 2-5
Front Panel Pushbutton Selection .................. 3-3
Typical Model 172A Current Display (DCnA). ............. 3-5
Typical Model l73A Current Display (ACmA). ............. 3-6
Typical 2 WIRE Resistance Measurement. ............... 3-7
Typical 4 WIRE Resistance Measurement. ...............
3-V
Semiconductor Diode and Transistor Testing ............. 3-10
Use of Multimeter Off Ground .................... 3-11
Model 1722 Digital Output Interface. ................ 3-14
Installation of Model I722 ..................... 3-15
Connector Pin Identification For ~1006 and PllOl .......... 3-17
Card-Edge Connectors (Model 1727 Cable Set). ............ 3-17
Location of Jumpers and Pull-ups on Model 1722 ........... 3-18
Model 1010 Single Rack Mounting Kit. ................ 4-2
Model 1017 Dual Rack Mounting Kit ................. 4-4
Overall Block Diagram of Model 172A/l73A .............. 5-2
Simplified Block Diagram of Signal Conditioning Circuits
................ 5-2
Simplified Schematic of DC Attenuator. ..... 5-6
Simplified Schematic of AC/DC Converter.
.....................................
5-7
Simplified Schematic of 173A I/V Converter 5-8
Simplified Schematic of Model l72A I/V Converter 5-8
Simplified Ohms Converter, Two-Wire Ohms Configuration ....... 5-10
Four-Wire Ohms Measuring Technique ................. 5-10
Simplified Schematic of Clamp. ................... 5-12
Simplified Schematic of Active Filter. ............. ., . 5-12
Simplified Block Diagram of A/D Converter. ............. 5-14
A/D Converter System Timing ....................
5-15
Simplified Schematic of A/D Buffer 5-16
Simplified Schematic of the A/D Converter,
.............................. 5-17
Simplified Schematic of 669 kHz Oscillator ........................... 5-19
Simplified Schematic of Reference Supply 5-20
Digital Display Multiplex Scheme
....................................... 5-22
Model 1722 Block Diagram . 5-24
Location of Calibration fidjustments. ................ 6-10
Location of Connectors and Test Points ............... 6-14
TOD and Bottom Cover Assembly ................... 7-3
iv

INSTRUCTION MANUAL
Digital Multimeter
Models 172A. 173A
GENERAL INFORMATION
-~- SECTION 1. GENERAL INFORMATION.
I-l.
INTROOUCTION. Thk Models, l72A and 173A Digital Multimeters are wide-range, general-
purpose measuring instruments, capable of measuring ac/dc voltage, ac/dc current and
resistance. (See Table 1-I for Specifications, Page l-2).
l-2. FEATURES.
a. Automatic Ranging and Polarity.
b. Manual Range Selection and Range Hold.
c. HI and LO Ohms Capability.
d. Line Operation.
e. Optional Battery Operation, Model 1728.
f. Floating Capability to +14OOV peak.
9. Optional Isolated Digital Interface, Model 1722/1723.
1-3. WARRANTY INFORMATION. The warranty is stated on the inside Front cover of the
manual. If there is a need for service, contact your Keithley representative or author-
ized repair facility as given in our catalog.
l-4. CHANGE NOTICE. Improvements or changes to the instrument not incorporated into
the manual will be explained on a change notice sheet attached to the inside back cover
of the manual.
l-5. OPTIONAL MODEL
1728 RECHARGEABLE BATTERY PACK. The Model 1728 is an accessory
battery pack which enables either line or battery operation. The Model 1728 has built-
in recharging circuitry. The Model 1728 is field-installed on the Model 172A/l73A chasis.
l-6. OPTIONAL MODEL 1722 DIGITAL INTERFACE. The Model 1722 is a field-installable
digital output option. It provides isolated open-collector ECD outputs and control lines.
1-7. OPTIONAL MOOEL 1723 IEEE STANDARD 488 BUS INTERFACE. The Model 1723 is a field-
installable digital interface option that provides logic and control functions necessary
to make the Model 172A or l73A bus compatible in accordance with the IEEE Standard 48B-
1975. Refer to the Instruction Manual for Model 1723 for operation and service instruction!
for this option.
IMPORTANT
The A Symbol can be found in various places in this Instruction Manual. Care-
fully read the associated CAUTION statements with regard to proper use and handling
of the instrument. Damage to the instrument may occur if these precautions are
ignored.
The \ symbol can be found in various places in this Instruction Manual. This
symbol indicates those areas on the instrument which are potential shock hazards.
Carefully read the associated WARNING statements with regard to proper use and
handling of the instrument. Serious personal injury may result if these pre-
cautions are ignored.
l-l

GENERAL INFORMATION INSTRUCTION MANUAL
Digital Multimet*r
TABLE 1-1. Models 112A,.113A
SPECIFICATIONS

INSTRUCTION MANUAL
Digital Multimeter
Models 172A. 173A
GENERAL INFORMATION
FUNCTION AND UNITS DISPLAY (mV)
I INPUT HI AND LO. UPPER PAIR
--
FIGURE l-1. Model 173A Front Panel.
1-3

IN= I nub I I”N MANUAL
Digital Multimeter
Models 172A. 173A
r
TEST POINT “A”
FIGURE l-2. Bottom View Showing Line Cord.
1-4