Keithley 192 User manual

Model 192
Instruction Manual
Contains Operating and Servicing Information for
Model 192 Programmable DMM and Model 1910 AC Option
Publication Date: June 1984
Document Number: 30983 Rev. C

WARRANTY
Keithley instruments, Inc. warrants this product to be free from defects
in material and workmanship for a period of 1 year from date of ship-
ment. During the warranty period, we will, at our option, either repair
or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley represent-
ative, or contact Keithley headquarters in Cleveland, Ohio. You will be
given prompt assistance and return instructions. Send the instrument,
transportation prepaid, to the indicated service facility. Repairs will be
made and the instrument returned, transportation prepaid. Repaired
products are warranted for the balance of the original warranty period,
or at least 90 days.LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from unauthorized
modification or misuse of any product or part. This warranty also does
not apply to fuses, batteries, or damage from battery leakage.
This warranty is in lieu of all other warranties, expressed or implied, in-
cluding any implied warranty of merchantability or fitness for a par-
ticular use. Keithley Instruments, Inc. shall not be liable for any indirect,
special or consequential damages.
STATEMENT OF CALIBRATION
This instrument has been inspected and tested in accordance with
specifications published by Keithley Instruments, Inc.
The accuracy and calibration of this instrument are traceable to the
National Bureau of Standards through equipment which is calibrated at
planned intervals by comparison to certified standards maintained in
the Laboratories of Keithlev Instruments, Inc.
Keithley Instruments, Inc. I instruments Division
28775 Aurora Road i Cleveland, Ohio 44139 , “.‘%A
Phone: [phone] / Telex: 98.5469

Instruction Manual
Model 192
Programmable DMM
01982, Keithley Instruments, Inc.
Cleveland, Ohio, U.S.A.
Document Number: 30983

SPECIFICATIONS
DC VOLTS

TABLE OF CONTENTS
PARAGRAPH TITLE PAGE
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
2.1
2.2
2.2.1
2.2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
3.1
3.2
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
SECTION l-GENERAL INFORMATION
Introduction ...................................................................................
Features .......................................................................................
WarrantyInformation ...........................................................................
ManualAddenda ...............................................................................
SafetySymbolsandTerms .......................................................................
Unpackingandlnspection ........................................................................
Specifications. ................................................................................
Preparation for Use ............................................................................
Line Power ....................................................................................
Line Voltage Selection ..........................................................................
LineFrequencySelection ................................................................... .~,~
Repackingforshipment .........................................................................
SECTION Z-ACCESSORIES
Introduction ...................................................................................
RackMountingKits .............................................................................
Model1019ARackMountingKit ................................................................
Model1019SRackMountingKit ................................................................
Model1600AHighVoltageProbe .................................................................
Model1641KelvinTestLeadSet..............................................................~~
Model165150AmpereShunt................................................................~ ...
Model1681Clip-OnTestLeadSet.............................................................~
Model1682ARFProbe......................................................................~ ...
Model 1683 Universal Test Lead Kit. .......................................................... ..
Model 1685 Clamp-On AC Current Probe ........................................................
Model1901CurrentAdapter ......................................................................
Model1910ACVoltageOption...............................................................~ ..
Model1920TRMSACVoltOption ................................................................
Model19231EEE-488lnterface...............................................................~~~~
Modal1924RearlnputAdapter..............................................................~.~~
Model7008IEEE.488Cable.. ..................................................................
SECTION 3-FRONT AND REAR PANEL CONTROLS
Introduction ...................................................................................
Front Panel ....................................................................................
BenchModeofOperation ........................................................................
Bench Programming Mode of Operation. .........................................................
SystemModeofOperation .......................................................................
RearPanel .....................................................................................
SECTION 4-BASIC DMM OPERATION
Introduction ...................................................................................
Powerup....................................................................................~
Operating Instructions
...........................................................................
zero .........................................................................................
Overrangelndication ............................................................................
Filter .........................................................................................
DCVoltageMeasurement ........................................................................
ResistanceMeasurement ...................................................................... .,
Four-Wire Ohms Measurement ...................................................................
AC Voltage Measurement (1910AC Option). ........................................................
AC Voltage Measurement l192OTRMS Optionl, ....................................................
1-l
l-l
l-l
1-l
l-l
l-l
l-l
l-l
1-2
l-2
1.2
1-2
2-l
2-1
2-l
2-1
2-l
2-1
2-l
2-l
2-2
2-2
2-2
2-2
2~3
2-3
2-3
2-3
2-3
3-1
3-l
3-l
3-l
3-l
3-2
4-l
4-1
4-l
4-l
4-2
4-2
4-3
4-3
4-4
4-4
45

TABLE OF CONTENTS (CONT.1
PARAGRAPH TITLE PAGE
SECTION ‘&FRONT PANEL PROGRAMS
5.1 Introduction 5-1
5.2 ....................................................................................................................................................................Program Notes 5.,
5.3 P,og,a,“OC,~~, ................................................................................
5.4 Programl.Resolution ........................................................................... ;I;
5.5 ProgramZ.Filter .........................................................................................................................................................
5-4
5.6 Program3.Dffset/Scale 5-4
5.7 Program4. Percent Deviation.. ...................................................................
5.8 Program5,Min/Max ............................................................................ z:E
5.9 Program&HI/LO/PASS
;:;(: Program7.DataLogger .................................................................................................................................................
5-J
5-B
lEEEBufferOpmt,on ...........................................................................
5.12 ProgramB.ServiceProgram ...................................................................... ;I;
SECTION 6-PERFORMANCE VERIFICATION
6.1 Introduction ...................................................................................
6.2 Environmental Conditions ........................................................................ E:;
6.3 RecommendedTestEquipment
6.4 InitialConditions ................................................................................................................................................... E:i
6.5 Performanceverification ......................................................................... 6-l
6.5.1 DC Voltage Accuracy Check 12OV to 12OOV ranges) ............................................. 6-l
6.5.2 DC Voltage Accuracy Check (.2V to2V ranges1 ................................................. ..
6.5.3 AC Voltage Accuracy Check (With Model 1910 AC Voltage Option Installed) ........................... ;I:
6.5.4 Resistance(R)AccuracyCheck ................................................................. 6-2
SECTION 7-THEORY OF OPERATION
7.1 Introduction ................................................................................... 7-l
7.2 Overall Functional Description .................................................................... 7~1
7.3 Analog Circuit Description ....................................................................... 7-3
7.3.1 InputMultiplexer ............................................................................. 7-3
7.3.2
DCVoltage Measurement
7.3.3 ResistanceMeasurement ............................................................................................................................................ ;:;
7.3.4 ACVoltageMeasurement
7.3.5 InputBufferAmplifier ............................................................................................................................................... ;I:
7.3.6 AIDConverter ............................................................................... 7-7
7.4 Digital and Display Circuit Description ..............................................................
7.4.1 Microcomputer (Refer to Schematic 309750) ..................................................... ;:;
7.4.2 Memon/
7.4.3 ..............................................................................................................................................................
AddressDecoder.. ;:;;
7.4.4 Reset ......................................................................................
7.4.5 FrontPanelSwitchPort ....................................................................... ;:;;
7.4.6 LineFrequency .............................................................................. 7.11
7.5 AIDControl .................................................................................. 7.11
7.5.1 ClockCircuit
7.6 DisplayCircuit ................................................................................................................................................................. ;I;:
7.7 PowerSupply ................................................................................. 7.14
SECTION E-MAINTENANCE
6.1 Introduction ................................................................................... B-l
6.2 Calibration ..................................................................................... 8.1
6.2.1 RecommendedTestEquipment ................................................................. B-l
8.2.2 Environmental Conditions ...................................................................... B-1
ii

TABLE OF CONTENTS (CONT.)
PARAGRAPH TITLE PAGE
8.2.3 Warmup ................................................
8.2.4 Calibration Adjustments ...................................
8.3 Troubleshooting Set-Up Procedures
...........................
8.3.1 Line Power Fuse iFlO1) Replacement ........................
8.3.2 Line Voltage Selection .....................................
8.3.3 Disassembly .............................................
8.3.4 Special Handling of Static Sensitive Devices ..................
8.4 Troubleshooting Procedure ...................................
8.4.1 Line Power ..............................................
8.4.2 A/D Converter and Display .................................
8.4.3 ACConverter ............................................
8.4.4 DC Attenuator and Ohms Sources and Resistors. ..............
8.4.5 DigitalBoard .............................................
9.1
9.2
9.3
9.4
9.5
SECTION B-REPLACEABLE PARTS
lntrodution ................................................
Parts List ..................................................
Ordering Information ........................................
Factory Service .............................................
Schematic Diagrams and Component Location Drawings .........
.....................
......................
......................
......................
.... .... ..... ......
......
......
......
......
......
......
......
8-l
ai
8-2
8-2
8-4
8.4
8-5
8-5
8-6
8-6
86
86
86
9-1
9-1
9-1
9-l
9- 1
iii

LIST OF ILLUSTRATIONS
FIGURE TITLE PAGE
l-l
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2.11
2-12
2-13
2.14
3-l
3-2
4-1
4-2
4-3
4-4
4-5
4-6
5-1
6-l
7~1
7-2
7-3
J-4
7-5
7-6
J-7
J-8
7-9
7-10
7-11
7-12
7.13
7-14
7.15
7-16
7.Ii
J-18
7-19
7-20
8-l
9-1
9-2
9-3
9-4
9-5
l-2
2-1
2-l
2-1
2-1
2-2
2-2
2-2
2~2
Instrument Packaging ...........................................................................
Model1019RackMountingKit ....................................................................
Model1600AHighVoltageProbe .................................................................
Model 1641 Kelvin Test Lead Set ..................................................................
Model165150AmpereShunt ....................................................................
Model1681Clip-OnTestLeadSet .................................................................
Model1682ARFProbe..........................................................~......~ ........
Model 1683 Universal Test Lead Kit ................................................................
Clamp-OnACCurrentProbe ......................................................................
Model1901CurrentAdapter.............................................................~ ........
Model1910ACVoltageOption ....................................................................
Model 1920 TRMS AC Voltage Option .............................................................
Model 1923 IEEE-488 Interface ..................................................... ..... .....
IEEE-488Connector....................................................................~..~ .....
Model1924RearlnputAdapter .................................................................
Modell92FrontPanel.............................~.............................~.~ .............
Model192RearPanel ..........................................................................
Effect of Zero Function on Dynamic Range of Measurements ....................... ................
InputFilterFiesponseGraph ......................................................................
DCVoltageMeasurements .....................................................................
ResistanceMsasurements................~..........................~............~......~...~ ..
Four-Wire Resistance Measurement .............................................. ..
ACVoltage Measurements ........................................................... ~, ...
Front Panel Program Buttons ................. .................... ....... .. ..
TestCircuit,2mVand2V............~ .........................................................
Basic Block Diagram .................................................................... ,.,
Simplified Multiplexer Schematic. .................................. ........... .....
DCVoltage Measurement .................................................... ., ., .....
FET Switching Sequence for DC Voltage Measurement (Bench Mode of Operation) .. ...... .. ..
DC Voltage Measurement FET Switching Sequence (System Mode of Operation1 ..... .. .. .. .. ..
Resistance Measurement Simplified Circuit ....... ~, .................. ...... .... ...
FETSwitchingSequenceforOhmsMeasurement ................................
Affect of Lead Resistance in 2.Terminal Ohms Measurements. ................ ..
Affect of Lead Resistance in 4.Terminal Ohms Measurements. .......................... .... .. ....
Block Diagram AC Volts Operation ...... ..... ............... ... ..........
ACVoltsOperationFlowChart..~ .................................... ~,.,~ ...... ~.~.~,, .....
Simplified Input Buffer Schematic .............. .....................
Simplified A/D Converter Schematic ............. ...................... ... .. .... ..... ....
AID Converter Integrator Output Waveform ....... .................................... ... ..
Microcomputer Block Diagram ..................................................................
ChargeBalanceTimming .....................................................................
SingleSlopePhase.........~.........................................................~ ........
Simplified Schematic of Latch .............................................................. ....
Simplified Oscillator/Divider Diagram .................................. ..........................
Display Schematic ................................................................. ...........
Adjustment Locations .............................................. ................. ..........
Exploded View With Mechanical Parts .............................................................
AC Converter, Component Location Drawing ......................................................
MotherBoard,ComponentLocationDrawing ......................................................
Analog Board, Component Location Drawing ......................................................
Display Board, Component Location Drawing ......................................................
2-3
2-3
2~3
2-3
2~3
2-J
3~:~
3-2
4~’
4~2
4~3
44
4~i
4~4
52
6-2
7~1
7~2
7~3
7-4
7~4
7~5
‘~6
M
7Yz
J-7
7~8
7-9
7-9
7.10
7~12
7~:3
7-14
7-15
7-15
7-16
8-3
9-2
9.11
9-13
9-17
9-21
iv

LIST OF ILLUSTRATIONS (CONT.)
FIGURE TITLE PAGE
9-6 AC Converter, Schematic Diagram g-23
9-7 MotharBoard.SchematicDiagram............................................................... 9.25
9-a Analog Board, Schematic Diagram g-29
9-9 Display Board, Schematic Diagram g-33
LIST OF TABLES
TABLE TITLE PAGE
4-l
4-2
4-3
4-4
5-l
52
6-l
6-Z
6-3
6-4
6-5
7-1
7-2
7-3
7-4
6-l
6-2
8-3
9-4
86
6-5
a-7
a8
a-9
a10
6-11
6-12
El3
6-14
9-1
9-2
9-3
9-4
9-5
LineVoltagaSalection ........................................................................... 4-l
MaximumInput ............................................................................... 4-1
ResistanceRanges ............................................................................. 4-3
Maximum Four-Wire Test Lead Resistance. ............................................ ..... 4-4
FrontPanalProgramSummary ................................................................... 5-l
Data Point Times .................................................................. ....... 5-9
Recommended Test Equipment for Performance Verification ...................................... .. 6-l
DC Voltage Performance Check (2OV to 12OOV Rangel ......................................... .. 6-2
ACVoltageAccuracyChack ..................................................................... 62
ZeroReading .................................................................................. 6-3
ResistanceAccuracyChack ..................................................................... 6-3
SenlingDelays.SNontoTurnonoflntegrator.. ......................................... ........ 7-8
MamoryByteLocations...............................................................~..~ .... 7-10
FunctionsofLatchOutputs .................................................................... 7-13
Power Supply Component Identification. .............................................. ..... 7-15
Recommended Test Equipment for Calibration .................................................... 6-l
CalibrationProcaduras.................................................................~~~ ...... a-2
Fuse Replacement ............................................................................. 6-4
LineVoltagaSalaction................................................................~~~~ ..... 6-4
TestNumberSummarization ..................................................................... 6-6
Static Sensitive Devices ......................................................................... 8-5
Program 8 A/D Test-FET Switching Sequence ......................................... ....... ... 6.7
LinePowarChecks................................................................~...~ ....... a-a
AIDConvarterChacks ..................................................................... .~~ 6.6
Display Checks.. ............................................................................. 6.9
ACConvartarCheckslModel1910) ................................................................ 6.9
DCAnanuatorChacks.....................................................................~ .... 6.10
Ohms Source and Resistors Checks. .............................................................. 9-l 1
DigitalBoardChecks....................................................................~..~.~ 6-11
Modal192DrawingPackage..............................................................~..~..~ 9-1
AC Converter PC-496, Parts List ............................................................ ..... 9-3
MotharBoardPC-559,PartsList........................................................~~ ...... 9.4
Analog Board PC-560. PartsList ............................................................ .. 9.6
Display Board PC-530, Parts List ................................................................ 9-9
v/vi

SECTION 1
GENERAL INFORMATION
1.1 INTRODUCTION
This instruction manual contains complete operating in-
structions for the Keithley Model 192. Detailed descriptions
of the available options for the Model 192 are provided
lseperate instruction manuals are supplied with the Model
1920 and Model 19231, along with a theory of operation,
calibration and service instructions for maintaining the in-
strument. A complete parts list with schematics and compo-
nent layouts is also provided at the end of this manual.
The Model 192 is a 6’h digit, 2,000,OOO count, fast
autoranging DMM. With the IEEE-468 interface option
(Model 1923). the Model 192 becomes fully programmable.
DC Volts and Ohms functions are standard. Measurements
of l&V to 12OOV are attainable on 5 voltage ranges, and
Z-and 4-terminal messurements of 1mD to ZOMR are at-
tainable on 6 resistance ranges. With the addition of the
Model 1910 AC Voltage Option, the Model 192 will provide
readings from 1OrV to 1OOOVAC on 4 ranges. True Root
Mean Square ITRMS) AC voltages can also be attained with
the use of the Model 1920 TRMS ACV Option. Because the
Models 1910, 1920, and 1923 are easily field installed, these
options can be added at any time.
1.2 FEATURES
The Model 192 includes the following features:
Front Panel Programs-The internal programs in the
Model 192 are accessible from the front panel. Descrip-
tions of these programs can be found in the detailed spe-
cifications which precede this Section and in Section 5.
Data Storage- Registers for storing 100 readings are pro-
vided in the basic Model 192. These storage registers are
utilized by Front Panel Program 7. Data Logger (see
Section 51.
Multiple Inputs-Multiple inputs provide access to DCV.
ACV, and Ohms terminals simultaneously. This enables
systems designers to optimize their switching matricies
for the parameter being measured. In addition, in some
simple systems, switching can be eliminated altogether.
For systems that require only one input, the Model 1924
Rear Panel Input Adapter is available as an option.
One Button Zero-The front panel zero is activated by
pushing one button. The zero offset is automatically scal-
ed when a new range is selected. Unique offset settings
are saved for each function.
1.3 WARRANTY INFORMATION
Warranty information is given on the inside front cover of
this manual. If there is a need to exercise the warranty, con-
tact the Keithley representative in your area to determine
the proper action to be taken. Keithley maintains service
facilities in the United States, West Germany, Greet Britain,
France, the Netherlands, Switzerland, and Austria. Informa-
tion concerning the application, operation or service of your
instrument may be directed to the applications Engineer at
any of the above locations. Check the inside Front Cover of
this manual for addresses.
1.4 MANUAL ADDENDA
Improvements or changes to this manual will be explained
on an addemdum attached to the inside back cover.
1.5 SAFEN SYMBOLS AND TERMS
Safety symbols used are as follows:
The symbol A on the instrument denotes that
the user should refer to the operating instructions.
The symbol i, on the instrument denotes that
1OOOV or more may be present on the terminal(sl.
The WARNING used in this manual explains dangers that
could result in personal injuy or death.
The CAUTION used in this manual explains hazards that
could damage the instrument.
1.6 UNPACKIrdG AND INSPECTION
The Model 192 was carefully inspected both mechanically
and electrically before shipment. Upon receiving the Model
192, unpack all items from the shipping container and check
for any obvious damage that may have occurred during
transit. Report any damage to the shipping agent. Retain
and use the original packaging materials if reshipment is
necessan/. The following items are shipped with all Model
192 orders:
l Model 192 Programmable DMM
l A Model 192 instruction Manual
l Installed or separate optional accessories, as ordered
1.7 SPECIFICATIONS
For Model 192 detailed specifications, refer to the specifica-
tions that precede this section.
1.8 PREPARATION FOR USE
The Model 192 is shipped ready for use on the line voltage
marked on its rear panel. The line frequency 150 to 400Hzl is
selected automatically by the Model 192 during power up. If
l-l

the Model 1923 IEEE Interface is installed it will be set to the
Addressable mode and et Address 8.
1.9 LINE POWER
The Model 192 is provided with a J-wire line cord which
mates with a third wire earth grounded receptacle. The in-
strument will operate on two of four voltage ranges listed in
Table B-4. These ranges may be selected by positioning an
internal slide switch and installing the appropriate fuse for
that range. An optional line voltage range of SO to 110 volts
is available by special order. Instruments with this range use
a different transformer.
1.10 LINE VOLTAGE SELECTION
Refer to Section 6 Maintenance to select the proper line
voltage settings.
1.11 LINE FREQUENCY SELECTION
Line frequency is sensed automatically by the Model 192
during power up. The instrument will operate at 50 to 400Hz
end will display F60 at 60Hz or F50 at either 50Hz or 400Hz.
1.12 REPACKING FOR SHIPMENT
The Model 192 should be packed in its original carton using
the packaging method shown in Figure l-l. Before packag-
ing, wrap the instrument in plastic. After it is placed in the
box, surround the instrument with styrofoam packaging
material.
If the Modal 192 is to be returned to Keithley Instruments for
calibration or rapair, include the following:
l AlTENTION REPAIR DEPARTMENT on the address label
l Warranty status of the instrument
l Completed service form
CARDBOARD STRIP
NSTRUCTION MANUAL
MODEL 192
PROTECTIVE
CARDBOARD
BOTTOM
ARDBOARD STRlP
PACKAGING MATERIAL
L 1
Figure l-l. Instrument Packaging
1-2

SECTION 2
ACCESSORIES
2.1 INTRODUCTION
This section describes the various accessories and options
available for use with the Model 192 OMM.
2.2 RACK MOUNTING KITS
2.2.1 Model 1019A Rack Mounting Kit
The Model 1019A is a universal rack mounting kit for the
Model 192. Two different front panels &weprovided to allow
left, right, or dual Iside-by-side) installation. ISee Figure
2-1.1
Figure 2-1. Model 1019 Rack Mounting Kit
2.2.2 Model 1019s Rack Mounting Kit
Model 1019s slide rack mounting kit enables one or two half
rack size instruments to be rack mounted with the added
feature of sliding the instrumentls) for easy access. The
dimensions are 133mm x 463mm (5% x 19 inl.
2.3 MODEL WOOA HIGH VOLTAGE PROBE
The Model 1600A (Figure 2-2) extends the DMM measure-
ment capabilities to 40kV. It has a 1M)O:l division ratio I1
lolt on the DMM corresponds to 1 kilovolt).
Figure 2-2. Model 16OOA High Voltage Probe
2.4 MODEL 1641 KELVIN TEST LEAD SR
The Model 1641 test leads (Figure 2.3) are used in making
4-terminal measurements. The test leads I1 pair1 are twin-
lead cables 1.2m 146 inches1 long. Each cable is terminated
by a twin-banana plug and a spring-clip Kelvin contact. Plug
the twin banana plugs into the DMM horizontallv (HI to HI
and LO to LO).
Figure 2-3. Model 1641 Kelvin Test Lead Set
2.6 MODEL 1661 66 AMPERE SHUNT
The Model 1651 (Figure 2-4) allows current measurements
to be made from 0 to 50 amperes DC and up to 50 amperes
AC with AC Voltage option. It is a 0.001 ohm + 1%
4-terminal shunt. A 50 ampere current will correspond to
50mV.
Figure 24. Model 1661 M Ampere Shunt
2.6 MODEL 1681 CLIP-ON TEST LEA0 SET
The Model 1661 (Figure 2-6) contains two leads 1.2117146in. I
long, terminated with banana plug and spring-action clip-on
probe.
2-l

Figure 2-6. Model 1661 Clip-On Test Lead Set
2.7 Model 1682A RF Probe
The Model 1662A is en RF probe that permits measure-
ments of AC voltages at frequencies from 1OOkHz to
250kHz. Connect the probe to the input terminals of the
DMM. Select the DCV function and the appropriate range.
The Model 1662A will give en output of one volt for an input
of one volt rms when usad with instruments having an input
impedance of 10MlI. ISee figure 2-6.)
Figure 2-6. Model 1662A RF Probe
2.6 MODEL 1663 UNIVERSAL TEST LEA0 KIT
The Model 1663 consists of two test leads 1.2m (48in. l long
with 12 screw-in tips, 2 banana plugs, 2 spade lugs, 2
alligator clips with boots, 2 needle tips with chucks, and 4
heavy-duty tip plugs. (See Figure 2-7.)
Figure 2-7. Model 1663 Universal Test Lead Kit
2.9 MODEL 1666 CLAMP-ON AC CURRENT PROBE
The Model 1666 (Figure 2-8) measures 60Hz and 60Hz AC
current by clamping onto a single conductor. Interruption of
the current path is unnecessary. The Model 1685 detects
current by sensing magnetic field produced by current.
Figure 24. Clamp-On AC Current Probe
2.10 MODEL 1901 CURRENT ADAPTER
The Model 1901 (Figure 2-91 allows the DMM to read DC
current from lnA/digit to 2000mA. With the Modal 1910
AC voltage option it reads from lOnA/digit to 2000mA. The
Model 1901 plugs into the INPUT terminals of the Model
192. Maximum allowable continuous voltage drop (full scale
input voltage burden) is 200mV. Shunt resistors are con-
nected to eliminate contact resistance errors. Use the Model
192 200mVDC range and 2VAC range for DC current and
AC current respectively. Input voltage burden can be reduc-
ed by selecting the lowest shunt that provides the necessary
resolution.
2-2

2.11 MODEL 1910 AC VOLTAGE OPTION
The Model 1910 (Figure 2-10) is a factory or field installable
option which allows the DMM to read AC volts from
lO@/digit to 1OOOV. The Model 1910 is internally installed
in the Modal 192. It is important to note that field installation
or removal/replacement of the Modal 1910 requires
recalibration of the Model 1910. Refer to the instructions ac-
information.
Figure 2-10. Model 1910 AC Voltage Option
2.12 MODEL 1920 TRMS AC VOLT OPTION
The Model 1920 is a True Root Mean Square ITRMSI AC
plug-in option for the Model 192 (Figure Z-11). The Model
1920 enables the Model 192 to measure the TRMS value of
an AC signal. When the Model 1920 is installed, an AC + DC
function is available. The Model 1920 has four ranges on
which an AC signal can be measured. It is field installable.
Refer to the instructions accompanying this option for
operation and installation information. It is important to
note that field installation or removal/replacement of the
Model 1920 requires recalibration of the Model 1920.
Figure 2-11. Model 1920 TRMS AC Voltage Option
2.13 MODEL 1923 IEEE-466 INTERFACE
The Model 1923 is a microprocessor-based IEEE Standard
466-1976 interface that provides the logic and control
necessary to interface the Model 192. In the Talk Only mode
the Model 192 can send data to one or more listeners with-
out the use of a controller. In the Talk/Listen mode the
Model 192 can send or receive data over the IEEE Bus when
addressed by a systems controller. (See Figures 2-12 and
2-13.) Also provides status output and external trigger con
nector to rear panel.
Figure 2-12. Model 1923 IEEE-466 lnterfsce
Refer to the Model 1923 IEEE-468 Interface Instruction
Manual for operation and installation procedures.
Figure 2-13. IEEE-466 Connector
2.14 MODEL 1924 REAR INPUT ADAPTER
The basic Model 192 has multiple inputs on the front panel.
The Model 1924 Rear Input Adapter provides multiple rear
inputs without the Model 1923 IEEE option. (See Figure
2-14.1 The IEEE option must be installed with the Model
1924 to use the single rear input on the Model 1924.
Necessav switching signals for the Model 1924 Input op-
tion are obtained through the status port connector which is
located on the rear panel. The status port is an integral part
of the IEEE ootion.
2.15 Model 7008 IEEE-466 CABLE
The Model 7008 is a 6ft l2m) IEEE-488 Digits Cable. The
cable has 24 stranded wire conductors and is terminated
with IEEE Standard 488 connectors.
2-3

STATUSPORT
CONNECTOR
FRONT PANEL
INPUT CONNECTOR
WHITE W,RE
Figure Z-14. Model 1924 Rear Input Adapter
2-4

SECTION 3
FRONT AND REAR PANEL CONTROLS
3.1 INTRODUCTION
This section describes the Model 192 front and rear panel
controls. Refer to Figures 3-1 and 3-2.
3.2 FRONT PANEL
The Front panel features are explained under the following
modes of operation:
l Bench Mode of Operation
l Bench Programming Mode of Operation
l System Mode of Operation
3.3 BENCH MODE OF OPERATION
Power ON/OFF Button-Power is ON with button IN;
power is OFF with button OUT.
Display-Display is direct reading in AC and DC volts. Ohms
is read in kfl, except the 20MR range which is read in
megohms. 5’h digits of resolution is standard in the Bench
mode.
IEEE-488 Bus Indicator-The indicators (Talk, Listen and
Remote1 are used during remote operation of the Model
192. They can be disregarded during the Bench mode of
operation.
Input Terminals-There are separate connections for DCV,
ACV, and Ohms with the use of five-way binding posts.
Range Push Buttons-These seven momentary switches
are used to select range. The annunciators indicate which
range the instrument is in, and if it is in Manual or Auto
ranging.
Function Push Buttons-These three push buttons select
either DCV, ACV lif the option is installed), or kR.
Zero Push Buttons-This button controls the internal Zero
program (See paragraph 4-41. An illuminated annunciator
indicates Zero function is enabled.
Programming Push Buttons-These two momentary swit-
ches are used during tha Bench Programming mode of
operation. They can be disregarded during the Bench mode.
Tilt Bail-The tilt bail is used as a handle and also to elevate
the front of the instrument for better Viewing.
3.4 BENCH PROGRAMMING MODE OF OPERATION
Power ON/OFF Button-Power is ON with button IN:
power is OFF with button OUT.
Display-The utilization of Front Panel PROGRAM 1 in-
creases resolution to 6% digits (see paragraph 5.41.
IEEE-466 Bus Indicator-The indicators (Talk, Listen and
Remote) are used during remote operation of the Model
192. They can be disregarded during the Bench mode of
operation.
Input Terminals-There are separate connections for DCV.
ACV, and Ohms with the use of five-way bindinq posts.
PROGRAM $ through PROGRAM 5-The number 0
.through 5 and the sign I-l to the left of the Range push but-
tons are used to select their corresponding programs or
enter data.
PROGRAM 7 through PROGRAM g--The number 7,8. and
9 at the left of the Function push buttons are “sed to select
their corresponding program or enter data,
PROGRAM 6-The number 6 at the left of the Zero push
button is used to select front panel PROGRAM 6 or enter
data.
Programming Push Buttons-PRGM-This button enables
the selection of front panel programs. RECALL-This butt
ton has three function levels or uses. The first function level
(RECALL) displays the currant program along with data, if
any. The second function level (ENTI is used to enter pro-
gramming data. The third function level is a trigger for the
System mode.
3.5 SYSTEM MODE OF OPERATION
Power ON/OFF Switch-Power is ON with button IN;
power is OFF with button OUT.
Display-In the System mode, the Model 192’s resolution is
determined by the conversion rata. Refer to IEEE-469 Bus
Operator Manual.
IEEE-466 Bus Indicator-These indicators (Talk. Listen and
Remote) identify the present status of the IEEE Bus.
Input Terminal-There are separate connections for DCV.
ACV, and Ohms with the use of five-way binding posts.
Range Push Buttons-These seven momentary switches
are used to select range. The annunciators indicate which
range the instrument is in, and if it is in Manual or Auto
Range.
Function Push Buttons-These three push buttons select
either DCV, ACV lif the option is installed), or k0.
3-1

Zero Push Buttons-This button controls the internal Zero
program ISee paragraph 4.4). An illuminated annunciator
indicates Zero function is enabled.
3.6 REAR PANEL
HIGH which are used with the internal program
HI/LO/PASS. The function outputs are continuously
active, the PASS, LOW, HIGH outputs are active only when
utilizing the HI/LO/PASS program. The external trigger re-
quires a 0 to 5V logic signal and is recognized only when in
The following information describes Model 192 rear panel
controls.
system mode.
IEEE-488 Interface Connector’-This is the IEEE-488 con-
Power Connector-The instrument will operate on four “action to the Modal 192.
voltage ranges of 50 to 400Hz AC power Isee paragraph 1.9
and 1.10). Address Switches*-These switches are used to set up the
Model 1923 IEEE-488 interface.
Fuse-See paragraph 8.5.1 for the proper fuse replacement.
Status Output’ and External Trigger-Six active low out- Accessory Mounting Holes-These are threaded mounting
puts and the external trigger input are available through the holes for the rear input adapter,
Status Output Connector. Three of the outputs are funtion
(ACV, DCV, kR). The remaining outputs are PASS, LOW,
l These functions are present when the Model 1923 option
is installed.
\ - \‘IWU. 1m1*.. I”“*Y) i- ,i
. 1 / \
Figure 3-1. Model 192 Front panel 1
Figure 3-2. Model 192 Rear Panel
3-2

SECTION 4
BASIC DMM OPERATION
4.1 INTRODUCTION
This section contains procedures for connecting and
operating the Model 192.
4.2 POWER UP
Plug the instrument into the proper power receptacle in ac-
cordance with Table 4-l.
Table 4-l. Line Voltage Selection
Input Switch Setting
Voltage s102
105-125VAC 115VAC
210-250VAC 230VAC
90-IlOVAC’ 115VAC
195235VAC’ 230VAC
‘For instruments equipped with a low voltage transformer,
lmmediatley after turning on the Model 192 via the POWER
switch, the Display will indicate the following:
rlzKm?q
1. This is a display test. The operator can note inoperative
display segments by comparing the Model 192’s display
with the figure above.
2. In addition, the push button and GPIB annunciators will
illuminate. All annunciators will illuminate simultaneously
if operating correctly.
After the display test is completed the Model 192 will display
the integration period and software level. For example;
when the following is displayed:
-1-6
1. The Model 192 senses the power line frequency and sets
the A/D conversion rate.
2. The F60 indicates that the integration time has been set
for 16.6 milliseconds.
3. The C4 is a code that identifies the software revision that
is installed in the Model 192.
4. If the following is displayed the F50 indicates that the in-
tegration time has been set for 20 milliseconds.
-1-5
4.3 OPERATING INSTRUCTIONS
Basic operation of the Modal 192 is presented in the follow-
ing paragraphs. The upper three binding posts are used for
voltage input connections. The lower four binding posts are
used for ohms connections. The LO binding posts for
ACV, DCV and 0 are wired together.
CAUTION
Do not apply voltages between the LO
binding posts. Instrument damage may
OCC”r.
WARNING
Maximum floating voltage is 1400VDC
or peak AC at <5 x 106V.H~. Do not ex-
ceed the maximum floating voltage
ratings. Destruction of insulation could
present e shock hazard.
The LO inputs may be floated at voltages up to 1.4kV at
5x 106V*Hz. with reference to chassis ground. Chassis
ground is connected to earth ground with the line power
cord and an appropriately grounded three-wire receptacle.
WARNING
Hazardous voltages may be present on
the LO input terminals. Any voltage that
is applied to LO will also be present at
the DLO terminals.
CAUTION
Do not exceed maximum input limits
given in Table 4-2.
DC voltage sources. AC voltage sources, and Resistance
values may be connected to the input termtnals
simultaneously with consideration for possible ground loops
and noise. Refer to Table 4-2.
Table 4-2. Maximum Input
Function [ Ranga
4.4 ZERO
Maximum Input
1200VDC or Peak AC
1OOOV rms sins or DC,
2x 10’V’Hz
360V peak or 250V rms
The Zero control serves as a baseline suppression subtract-
ing a stored offset or measured value from a subsequent
measurement. When the Zero control is enabled, the Zero
LED will light. All readings displayed while in the Zero mode
are the difference between the stored baseline and the
actual voltage level. The baseline obtained while the Zero
control is enabled represents a specific level or quantity of
volts or ohms. For example, if 1OOmV is zeroed. then,
1OOmVDC represents the specific level of the Zero baseline.
One hundred millovolts will then be automatically sub-
tracted from readings on any DCV range. The value for the
4-l

baseline can be as little as a few microvolts or as large as
999 volts. This capacity enables the user to zero a wide
range of voltages. For example:
Displayed Push Apply Displayed
offset Zero Input Result
Example #l 1.23000 .ooooo 1.ooooo - .23000
Example #2 .23000 .ooooo 1.ooooo .77000
Note
Setting range lower than the zero baseline
value, will overrange display.
WARNING
The voltage present on the input may be
measured
greater than the displayed reading when
SOV = displayed reading
the instrument is Zeroed.
One baseline can be stored for each of the functions (DC
Example: 1OOV = stored baseline
lSOV=actual voltage to be
Volts, AC Volts, and Ohms). For example, 20mVDC can be
stored for DC volts, 1OVAC volts and 50 can be stored for
4.6 OVERRANGE INDICATION
Overrange is indicated by the following display:
If the overflow is negative then a minus I-) prefix will
precede the displayed OFLO.
\
Figure 4-l. Effect Of Zero Function on Dynamic Range
/
9
of Measurement
,HPllTO”~lWCPAHW
4.6 FILTER
ohms. Proceed as follows:
1. To store a zero value for DC volts, select the DC Volts
function. Press the ZERO Button. The reading on the
Model 192 display will be stored as the zero value. The
zero control can be disabled by pressing the ZERO button
again.
2. To store a zero value for AC volts, select the AC volts
function. Press the Zero button. The reading on the
Model 192 display will be stored as the zaro value. The
zero control can be disabled by pressing the ZERO button
again.
3. To store a zero value for Ohms, select the Ohms func-
tion. Press the ZERO button. The readina on the Model
192 display will be stored as the zero value. The zero con-
trol can be disabled by pressing the ZERO button again.
4. The Model 192 will retain these zero values. If the func-
tion is changed the Model 192 will recall the value of zero
that was set for that function. To replace an earlier stored
zero value, simply press the ZERO button twice. The
reading that was on the Model 192 will be stored as the
new zero value.
The Model 192 employs digital filtering techniques. There
are three internal filter routines. Figure 42 shows the filter
response curves. In the Bench mode of operation, the inter-
nal computer automatically selects the filter. Filter 1 is
selected on 5’S digit readings and filter 2 on 6% digit
readings.
An exception to this is a 20 digit window selected on the
20MIl range in the 5H digit mode of operation. In the 6%
mode a 60 digit window (filter 2) is selected, similar to other
6% digit modes.
When a large input change is sensed, the microprocessor
disables the digital filter. This permits a fast response to the
input (as noted by A in Figure 4-2). When the reading nears
its final value, the filter is turned on (as noted by 6 in Figure
4.2). This permits low noise senling to the final value.
A third filter, filter 3, is available through the front panel pro-
gram number two. Filter routines 1, 2, and 3 can be pro-
grammed through the IEEE programming option. Refer to
the IEEE-466 Instruction Manual for Bus operation.
It is important to note that the use of zero reduces the
dynamic range of measurement. For instance, if
+ l.OOOOOVDC is the zeroed value, input voltages greater
than 2V would still overload the AID converter (200,000
counts). even though overrange would occur at approxi-
mately 100,000 counts displayed. Readings less than -lV
would cause overrange (2V less than + 1Vl because of the
maximum display reading of 199,999 counts. This reduction
in the dynamic range of the measurement is illustrated in
Figure 4-1. In DCV function, both the Displav dvnamic
range and the Input dynamic range can be &wed& and
thus, both can limit the dynamic range of the measurement. Figure 4-2. Input Filter Response Graph
4-2