Keithley 1910, 192 Service manual

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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

material and workmanship for a period of 1 year from date of shipment. 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, including any implied warranty of merchantability or fitness for a particular 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: (216) 248-0400 / Telex: 98.5469

Instruction Manual

Model 192

Programmable DMM

01982, Keithley Instruments, Inc.

Cleveland, Ohio, U.S.A.

Document Number: 30983

SPECIFICATIONS

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

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..

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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-l 2-2 2-2 2-2 2-2 2~3 2-3 2-3 2-3 2-3

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 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,

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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

SECTION ‘&FRONT PANEL PROGRAMS

5.1

5.2

5.3

5.4

5.5

5.6

5.7

5.8

Introduction

.................................................................................................................................................................... Program Notes

P,og,a,“OC,~~, ................................................................................

Programl.Resolution ProgramZ.Filter

Program3.Dffset/Scale

Program4. Percent Deviation.. ...................................................................

Program5,Min/Max

5.9 ;:;(: Program7.DataLogger

5.12 ProgramB.ServiceProgram

6.1

6.2

Program&HI/LO/PASS lEEEBufferOpmt,on

SECTION 6-PERFORMANCE VERIFICATION

Introduction ...................................................................................

Environmental Conditions ........................................................................

6.3

6.4

6.5

6.5.1

6.5.2

6.5.3

6.5.4

7.1

7.2

7.3

7.3.1

7.3.2

7.3.3

RecommendedTestEquipment InitialConditions Performanceverification

DC Voltage Accuracy Check 12OV to 12OOV ranges) DC Voltage Accuracy Check (.2V to2V ranges1 AC Voltage Accuracy Check (With Model 1910 AC Voltage Option Installed) Resistance(R)AccuracyCheck

SECTION 7-THEORY OF OPERATION Introduction Overall Functional Description Analog Circuit Description

InputMultiplexer .............................................................................

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DCVoltage Measurement

ResistanceMeasurement

7.3.4 ACVoltageMeasurement

7.3.5

7.3.6

7.4

7.4.1

7.4.2

7.4.3

7.4.4

7.4.5

7.4.6

7.5 AIDControl ..................................................................................

7.5.1 ClockCircuit

7.6 DisplayCircuit

7.7

InputBufferAmplifier

AIDConverter ...............................................................................

Digital and Display Circuit Description

Microcomputer (Refer to Schematic 309750) Memon/ AddressDecoder..

Reset ......................................................................................

FrontPanelSwitchPort LineFrequency

PowerSupply

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TITLE

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PAGE

5-1

5., ;I;

5-4

5-4 z:E

5-J 5-B

;I;

E:; E:i

;:;; ;:;;

7.11

7.11 ;I;:

7.14

6-l 6-l

;I:

6-2

7-l 7~1 7-3 7-3 ;:;

;I: 7-7

;:;

SECTION E-MAINTENANCE

6.1 Introduction ...................................................................................

6.2 Calibration

6.2.1 RecommendedTestEquipment

8.2.2 Environmental Conditions

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

B-l

8.1 B-l

TABLE OF CONTENTS (CONT.)

PARAGRAPH

8.2.3

8.2.4

8.3

8.3.1

8.3.2

8.3.3

8.3.4

8.4

8.4.1

8.4.2

8.4.3

8.4.4

8.4.5

9.1

9.2

9.3

9.4

9.5

Warmup ................................................

Calibration Adjustments ...................................

Troubleshooting Set-Up Procedures

Line Power Fuse iFlO1) Replacement

Line Voltage Selection .....................................

Disassembly .............................................

Special Handling of Static Sensitive Devices

Troubleshooting Procedure ...................................

Line Power ..............................................

A/D Converter and Display .................................

ACConverter ............................................

DC Attenuator and Ohms Sources and Resistors. DigitalBoard

SECTION B-REPLACEABLE PARTS

lntrodution ................................................

Parts List ..................................................

Ordering Information ........................................

Factory Service

Schematic Diagrams and Component Location Drawings

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TITLE

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PAGE

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

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

TITLE

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

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PAGE

l-2 2-1 2-l 2-1 2-1 2-2 2-2 2-2 2~2 2-3 2-3

2~3

2-3

2~3

2-J

3~:~

3-2

4~’

4~2

4~3

4~i

4~4

6-2

7~1 7~2

7~3 7-4 7~4

7~5 ‘~6

7Yz

J-7

7~8

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

LIST OF ILLUSTRATIONS (CONT.)

FIGURE

9-6

9-7 MotharBoard.SchematicDiagram............................................................... 9.25

9-a 9-9

AC Converter, Schematic Diagram g-23 Analog Board, Schematic Diagram

Display Board, Schematic Diagram

TITLE

PAGE

g-29 g-33

LIST OF TABLES

TABLE 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

TITLE

LineVoltagaSalection MaximumInput

ResistanceRanges .............................................................................

Maximum Four-Wire Test Lead Resistance. FrontPanalProgramSummary Data Point Times Recommended Test Equipment for Performance Verification

DC Voltage Performance Check (2OV to 12OOV Rangel ACVoltageAccuracyChack

ZeroReading ..................................................................................

ResistanceAccuracyChack .....................................................................

SenlingDelays.SNontoTurnonoflntegrator..

MamoryByteLocations...............................................................~..~

FunctionsofLatchOutputs ....................................................................

Power Supply Component Identification.

Recommended Test Equipment for Calibration

CalibrationProcaduras.................................................................~~~

Fuse Replacement .............................................................................

LineVoltagaSalaction................................................................~~~~

TestNumberSummarization .....................................................................

Static Sensitive Devices .........................................................................

Program 8 A/D Test-FET Switching Sequence

LinePowarChecks................................................................~...~

AIDConvarterChacks .....................................................................

Display Checks..

ACConvartarCheckslModel1910) ................................................................

DCAnanuatorChacks.....................................................................~

Ohms Source and Resistors Checks. ..............................................................

DigitalBoardChecks....................................................................~..~.~

Modal192DrawingPackage..............................................................~..~..~

AC Converter PC-496, Parts List

MotharBoardPC-559,PartsList........................................................~~

Analog Board PC-560. PartsList

Display Board PC-530, Parts List

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PAGE

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.~~ 6.6

.... 6.10

.....

4-l 4-1 4-3 4-4 5-l

6-l 6-2

6-3 6-3 7-8

7-10 7-13

7-15

6-l a-2 6-4

6-4 6-6 8-5

6.7

a-a

6.9

9-l 1 6-11

9-1

9-3

9.4

9.6

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 instrument. A complete parts list with schematics and component 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 attainable 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. Descriptions of these programs can be found in the detailed specifications which precede this Section and in Section 5.

Data Storage- Registers for storing 100 readings are provided 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 scaled when a new range is selected. Unique offset settings are saved for each function.

the proper action to be taken. Keithley maintains service facilities in the United States, West Germany, Greet Britain,

France, the Netherlands, Switzerland, and Austria. Information 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

on the instrument denotes that

the user should refer to the operating instructions.

The symbol

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:

Model 192 Programmable DMM

A Model 192 instruction Manual

Installed or separate optional accessories, as ordered

1.7 SPECIFICATIONS

For Model 192 detailed specifications, refer to the specifications that precede this section.

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, contact the Keithley representative in your area to determine

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 instrument 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.

CARDBOARD STRIP

NSTRUCTION MANUAL

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:

AlTENTION REPAIR DEPARTMENT on the address label

Warranty status of the instrument

Completed service form

MODEL 192

PROTECTIVE

CARDBOARD

BOTTOM

ARDBOARD STRlP

1-2

PACKAGING MATERIAL

Figure l-l. Instrument Packaging

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 &we provided to allow left, right, or dual Iside-by-side) installation. ISee Figure 2-1.1

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 2-1. 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 2-3. 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 1.2117 146in. I

long, terminated with banana plug and spring-action clip-on probe.

2-l

Figure 2-7. Model 1663 Universal Test Lead Kit

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.)

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 connected 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.

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 2-10. 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

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

FRONT PANEL

INPUT CONNECTOR

Figure Z-14. Model 1924 Rear Input Adapter

STATUSPORT

CONNECTOR

WHITE W,RE

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:

Bench Mode of Operation

Bench Programming Mode of Operation

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 switches 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

Display-The utilization of Front Panel PROGRAM 1 increases 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 buttons 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 programming 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.

Power ON/OFF Button-Power is ON with button IN: power is OFF with button OUT.

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 The following information describes Model 192 rear panel

controls.

Power Connector-The instrument will operate on four voltage ranges of 50 to 400Hz AC power Isee paragraph 1.9 and 1.10).

Fuse-See paragraph 8.5.1 for the proper fuse replacement. Status Output’ and External Trigger-Six active low out-

puts and the external trigger input are available through the

Status Output Connector. Three of the outputs are funtion

(ACV, DCV, kR). The remaining outputs are PASS, LOW,

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 requires a 0 to 5V logic signal and is recognized only when in system mode.

IEEE-488 Interface Connector’-This is the IEEE-488 con“action to the Modal 192.

Address Switches*-These switches are used to set up the Model 1923 IEEE-488 interface.

Accessory Mounting Holes-These are threaded mounting holes for the rear input adapter,

These functions are present when the Model 1923 option is installed.

\ - \‘IWU. 1m1*.. .

1 /

Figure 3-1. Model 192 Front panel

Figure 3-2. Model 192 Rear Panel

I”“*Y) i-

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

Voltage

105-125VAC

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:

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. 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 integration time has been set for 20 milliseconds.

4.3 OPERATING INSTRUCTIONS

Basic operation of the Modal 192 is presented in the following 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.

Switch Setting

s102

115VAC

rlzKm?q

-1-6

-1-5

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 exceed 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

4.4 ZERO 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

[ Ranga

Maximum Input 1200VDC or Peak AC

1OOOV rms sins or DC,

2x 10’V’Hz 360V peak or 250V rms

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:

4.6 OVERRANGE INDICATION Overrange is indicated by the following display:

Displayed Push

offset Zero Input Result

Example #l 1.23000 .ooooo Example #2 .23000 .ooooo

Note

Setting range lower than the zero baseline

value, will overrange display.

WARNING

The voltage present on the input may be

greater than the displayed reading when

the instrument is Zeroed.

Example: 1OOV = stored baseline

lSOV=actual voltage to be

measured

SOV = displayed reading

One baseline can be stored for each of the functions (DC Volts, AC Volts, and Ohms). For example, 20mVDC can be stored for DC volts, 1OVAC volts and 50 can be stored for 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 function. 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.

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 approximately 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.

Apply

1 .ooooo - .23000 1 .ooooo .77000

Displayed

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

of Measurement

4.6 FILTER 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 internal 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 programmed through the IEEE programming option. Refer to

the IEEE-466 Instruction Manual for Bus operation.

Figure 4-2. Input Filter Response Graph

,HPllT O”~lWC PAHW

4-2

4.7 DC VOLTAGE MEASUREMENT The Model 192 reads DC voltage from 1aV to 1200V. DC

volts are measured as follows:

CAUTION

Do not exceed the 1ZOOVDC maximum

allowable input voltage rating. Instru-

ment damage may occur.

1. Turn power ON by pressing the POWER ON/OFF button. If the instrumc?t is within 0°C to 50°C. it is useable immediately, but a two hour warmup is required to obtain rated accuracy.

2. Press DCV button. The Model 192 will enter the DCV mode automatically at power up.

3. Zero instrument on the .2V range. Zero must be set with the Zero function for rated accuracy. Zeroing is necessary to compensate for thermal EMFs generated by the connections to the circuit to be measured. These voltages may be only a few microwIts or several tens of microvolts. Set Zero as follows: A. Set the output of test circuit for zero volts or discon-

nect the test leads at the circuit and short them.

B. Set the Model 192 on the .2V range.

C. Press the ZERO button.

D. Select range from the five ranges available. The

decimal point is positioned by the Range button. The 1200V range is selected by the 2000 button. If the

20MR is inadvertently pressed when in the DCV function, the Model 192 will set the range to 1200V.

4. Connect input between the DCV and LO (see figure 43). The binding posts accept wires, spade lugs, or banana plugs for ease of connecting the potential to be measured. Low thermal cabling atid connections are recommended for measurements on the .2V range.

CAUTION

Do not exceed the 1200VDC maximum allowable input voltage rating; Instrument damage may occur.

5. Take readings by observing the displayed digits and decimal Point locations. All ranges are direct reading in volts.

4.6 RESISTANCE MEASUREMENTS The Model 192 DMM measures resistance from lm$figit to

20Mn. The Model 192 provides automatic 2.wire or 4.wire ohms operation (see paragraph 4.9 for d-wire ohms measurements). Measure resistance as follows:

1. Turn on power by pressing the POWER ON/OFF button.

2. Press kR button.

3. Select range from the six ranges available lor autorangei. The decimal point is positioned by the Range button.

4. Connect input between n and LO Isee Figure 4-4).

5. Accomplish Zero for a 2.wire or 4.wire measurement on the .2kQ range. Zero must be set with the Zero function

to obtain rated accuracy. Zeroing is necessav to cornpensate for test lead resistance on 2.wire measurements and for thermal EMFs on 2. and 4.wire measurementS. set zero as follows: A. Disconnect the test leadsat the circuit to be measured

and short them. B. Press the “ZERO” button. C. Reconnect the test leads.

6. Take reading. CAUTION

Maximum allowable input voltage lall ohms rangesl: 38OV peek, 250V rms. Do not exceed maximum voltage. Instrument damage may occur. Table 4-3

lists the maximum outputs for all the resistance ranges.

Table 4-3. Resistance Ranges

INPUT IMPEDANCE:

Figure 4-3. DC

1OOOMD on 2V-20V ranges 1OMn on 2OOV-1200V ranges

Voltage Measurements

Range

Setting I (Shorted1

* HI binding post Ired) is negative. ** Zero must be set to obtain rated accuracy~

Maximum Outputs*

v IOpen) ~

4-3

Figure 4-4. Resistance Measurements

Figure 4-5. Four-Wire Resistance Measurement

4.10 AC VOLTAGE MEASUREMENT II910 AC Option)

4.9 FOUR-WIRE OHMS MEASUREMENT For 4-wire measurements. connect the sense leads to the

circuit to be measured and to the fi SENSE terminals on the

Model 192 (see Figure 4-5). This arrangement eliminates the error due to the voltage drop ecross the current-carrying leads. Accurate, high resolution ohms measurements are obtained using 4wire connections.

Four-wire ohms measurements are recommended when

utilizing the .2k. 2k. or 20k0 range. Maximum test lead

resistance for 4-wire ohms measurement is given in table

4-4.

Table 4-4. Maximum Four-Wire Test Lead Resistance

Lead

Range

.2k 2k 20k 200k 2000k 20M

Resistance+

70 220 700

2200 7oon

22000

“Maximum resistance per lead for en additional 1 digit error et 6K digits.

With the Model 1910 option, the Model 192 reads AC volteges from 1OpV digit to 1OOOV. The instrument is average responding and is calibrated to the root mean sauare value of e sine weve. with a freauencv span of 20Hz

to 100kHz.

INPUT IMPEDANCE: 2MR shunted

by less than

5OpF

Figure 4-6. AC Voltage Measurements

CAUTION

Do not exceed maximum allowable input voltage. Instrument damage may occur. Maximum input is both the

voltage and voltage hertz product. If

maximum ratings ara exceeded, instrument damage will occur.

It is recommended that measurements greater than 150

volts and 2OkHz be made in the Manual ranging mode to

pravant autoranging to an incorrect range. This is due to the

decreased accuracy specified above 20kHz.

Accuracy is specified for 1000 counts and above. The maximum reading is 199999 at 5’h digits. Overrange is indicated

by OFLO. Maximum allowable input is 1OOOV rms or DC; 2x lOW*Hz. Measure AC voltage as follows:

1. Turn power ON by pressing POWER ON/OFF button.

2. Press ACV button. NOTE

The Model 192 will display “NO AC” if AC is selected without an AC option installed.

3. Select range from the four ranges available. The decimal point is positioned by the Range button. The 1OOOV

range l75OV range if the Model 1920 is intalledj is selected with the 2000 button. If the 20MQ button is inadvertently pressed when in ACV function, the Model

192 will set the range to 1OOOV.

4. Zero OFF unless measurements are to be made as deviations from a preset value.

NOTE

Do not use the ZERO button to zero the AC

function. A small residual voltage is normal

lapproxiamtely 200rV). If ZERO is used, the reading will be low by the amplitude of the zeroed residual voltage.

5. Connect input to be measured between the ACV and LO binding posts (see Figure 4-61.

6. Take reading.

4.11 AC VOLTAGE MEASUREMENT (1920 TRMS Option)

A separate manual is provided with the Model 1920 containing installation, operation and calibration instructions.

6514.6

SECTION 5

FRONT PANEL PROGRAMS

5.1 INTRODUCTION

This section contains information and instructions

necessary for operating the nine internal programs of the Model 192. These programs are run by depressing the front panel PRGM button, along with the button representing the

appropriate program number. Some of the programs require

numerical constants that must be entered from the front panel by using the numbered buttons. Other programs will display appropriate messages. Program examples are provided when necessary to instruct the operator in practical applications. For basic operation of the front panel buttons,

refer to Section 4. The programs, which are summarized in Table 5-l. are explained in detail in the following paragraphs. Refer to Figure 5-1 for front panel details.

5.2 PROGRAM NOTES

1. Most of the front panel buttons serve a dual purpose. The Range, Function, end Zero buttons are numbered in sequence. These numbered buttons are used when a

program number or numerical constant is to be entered.

2. Each program is entered by depressing the PRGM but-

ton followed by the desired program number.

3. PROGRAM$is used to cancel all other programs except

PROGRAMS 1 end 2. An appropriate clear message is

displayed when this program is entered.

4. PROGRAM 1, which controls the display resolution, and PROGRAM 2, which controls the internal filter, may both be used with any other program.

5. PROGRAMS 3 through 7 are mutually exclusive; only one of these programs may be used at any one time.

6. New programs may be entered without clearing a program that is presently running. To do so, depress the PRGM button, followed by the desired program number.

7. Anempting to enter an invalid program number will result in the following error message:

B. The numerical constants used for each program are

stored separately and will not change unless entered at the appropriate point in each program. Constant values

will be lost if the power is turned off.

9. Constants are to be entered when the operator is

prompted to do so by the instrument. When entering a numerical constant:

A. The constant is entered by depressing the numoereo

buttons in the desired sequence.

B. The decimal point is automatically placed in accor-

dance with the allowable range of the constant.

C. Data is entered into the digit whose “c” segment is

fleshing by pressing the desired numbered button. The “c” segment of a display digit is shown below:

E-8, ,,

c segment

As each digit is entered, the blinking segment will move one place to the right until all the necessary digits have been entered.

D. Only a 0 or 1 may be entered as the first digit for any

of the constants.

Table 6-l. Front Panel Program Summary

Program Number Operation

1 2 3

4 :

7 B

‘The Service Program is intended for use only by qualified personnel. See Section 8 of this manual for complete details.

Clears PROGRAMS 3-7 Display Resolution Filter Mode Offset/Scale

Percent Deviation Min/Max High/Low/Pass

Data Logger

Service’

Required Constant

None None None S (scaling factor) b (offset) n (comparison constant1 None LOL (low limit) HIL (high limit) r (time interval1 None

6-l

192 PROGRAMMABLE DMM

Y--c71 n n 17 17

DCV AC”

6-2

MINUS 1-l

NUMBERS 0 THROUGH 5

NUMBERS 6 THROUGH 9

PRGM

E ENT/RECALL

Figure 6-l. Front Panel Program Buttons

E. Only es many significant digits es necessary need to

be entered. The Model 192 will complete the constant with trailing zeroes where necessary.

F. Invalid keys will be ignored. If an invalid key is

depressed, the blinking “c” segment will remain at the current digit.

G. If an incorrect digit is entered, the complete constant

must be reentered. The new value may be entered by cycling the display around to the beginning by repeatedly depressing one of the number buttons.

H. A neoative constant mev be entered bv deoressina

I~ I

the front panel minus (-I button. The display will the; show a negative number. This mey be done at any point in the numeric input sequence. Depressing the

minus button a second time will restore the constant

to s positive value.

If too many digits are entered, the display will begin

again et the first digit on the left. All the digits in the constant must then be entered again.

Once all the digits of the desired constant are shown on the display, the constant is entered into the program by depressing the front panel ENT button.

The number of significant digits to be entered for s constant will depend on the display resolution mode in use. In the 5 H digit mode, only five digits after the

leadingfi or 1 may be entered. In the 6 !4 mode, up to

six digits in addition to the leading 0 or 1 may be entered.

10. PROGRAMS 3 through 7 will be terminated if the Model 192 receives a Remote Enable command over the IEEE-488 bus. PROGRAM&through 2 are not affected by the Remote Enable command.

Note

If it becomes necessary to exit a program in

progress (for example, to change resolution with PROGRAM 1, or change the filter mode with PROGRAM 21, readings will be missed while the instrument waits for the operator

to enter the desired program number.

11. When the front panel PRGM button is pressed, the instrument will prompt the operator to enter the desired program number by displaying the following message:

Note that the question mark on the display will blink

until a program number is entered. Depressing en invalid button at this point will result in the following message, which will be displayed for K second:

[no]

gram, the following message will be displayed for H second:

j-z-T-q

13. While PROGRAMS 3 through 7 era being run, the front panel PRGM indicator light will be on. This light will go off if the program is cancelled. either by using PROGRAM 8: or if the Remote Enable command is received over the IEEE-488 bus.

14. The front panel PRGM button will be inoperative if the IEEE REMOTE indicator light is on. Once the instrument is in the Remote mode, the following IEEE command

sequence must be sent to restore front panel program-

ming operation: GTL (Go to Local); DCL (Device Clear). For more information on IEEE commands. refer to the Model 1923 Instruction Manual. Alternately. the instrument may be turned off and then powered-up again to restore programming operation. Of course. any con-

stants previously stored will be lost, and the instrument will return to the power-on default conditions.

15. When PROGRAMS 3 through 7 are entered, the AUTO

range will be cancelled. The instrument will stay on the present range when one of these programs is entered

6.3 PROGRAM 0. CLEAR PROGRAMtimey be used to cancel PROGRAMS 3 through

7. This program is entered by depressing the PRGM switch

followed by the 0 button es follows:

1. Press PRGM. The instrument will display the following, indicating it is waiting for s program number:

r-Fzi-71

2. Press 0. The following message will be displayed for approximately % second:

[ml

3. Immediately following the program number indication. the following message will be displayed for Ih second:

4. PROGRAMS 3 through 7 will be cancelled. and the

Model 192 will return to the normal operating mode by displaying readings. The operation of the Function.

Range, and Zero buttons will be restored after PRO-

GRAM 0 is entered.

5. Depressing the RECALL button after PROGRAM fi has been run will cuese the following message to be dis-

played for H second:

12. The Range, Function, and Zero buttons are locked out while PROGRAMS 3 through 7 sre in progress. The operator must exit the program if these parameters are to

be changed. If en invalid key is pressed durinp a pro-

6-3

5.4 PROGRAM 1. RESOLUTION The display resolution of the Model 192 may be changed to

5’h or 8% digits by running PROGRAM 1. If has no effect on the date transmitted over the IEEE-488 bus, and may be used with PROGRAMS 3 through 7. Each time PROGRAM 1 is entered. the instrument will change display resolution modes. Upon power-up, the instrument is in the 5H digit display mode. To change the resolution. PROGRAM 1 may be entered as follows:

1, Press PRGM. The Model 192 will respond with the usual

prompt for a program number as follows:

-1

normally enabled for the 6H digit mode. For a more complete description of these routines, refer to paragraph 4.6.

PROGRAM 2 controls operation of a third available filter, filter 3. Each time PROGRAM 2 is entered, the state of filter

3 is changed. If filter 3 was previously enabled, entering

PROGRAM 2 will turn filter 3 off, If the filter was previously

disabled, PROGRAM 2 will turn the filter on. Upon power-

up, filter 3 is disabled. The mode of filter~3 may be changed by entering PROGRAM 2 as follows:

1. Press PRGM. The instrument will respond with the usual prompt for a program number:

r-?z-7-\

2. Press 1. The unit will indicate it has entered PROGRAM 1 by displaying the following message for H second:

3. If the instrument was previously in the 5!4 digit mode, it will change to the 6H digit mode as indicated by the following message, which will be displayed for approx-

imately W second:

[s.;

Readings made in the 6H digit mode are made at a slower rata, es indicated by the flashing rate of the decimal point.

4. If the instrument was previously in the 6H digit mode, it will change to the 5% digit mode and display the follow-

ing message for ‘h second:

[s.s

5. After PROGRAM 1 has been run, the Model 192 will continue to display normal readings. PROGRAMS 3 through

7 may be entered et this time without effecting display

resolution.

6. Example: Assume the Model 192 is connected to a DC voltage source and is in the 5K digit mode on the 20V range. A tYpical 5H digit display reading might be:

r-i-Gmq

After entering PROGRAM 1, the display reading might change to:

Note that the lest digit was roundedoff when the instrument was in the 5% digit display mode.

5.5 PROGRAM 2. FILTER

The Model 192 has a digital filter that is useful for minimiz-

ing the effects of noise on the readings. Normally, filter 1 is enabled for the 5’h digit resolution mode, while filter 2 is

2. Press 2. The program will be entered es indicated by the following message which will be displayed for % second:

p.YG-iq

3. If the filter was previously turned off, the filter will be enabled, and the following message will be displayed for

H second:

4. If the filter was on, it will be disabled. end the following

message will be displayed for approximately ‘/2 second:

NOTE

If the filter is not in the desired mode, it may be chenged by running PROGRAM 2 again. To do this, simply depress the PRGM end 2 buttons in sequence a second time. Each time PROGRAM 2 is entered, the filter mode changes to the alternate state.

5. Once PROGRAM 2 has been entered, the Model 192 continues normal operation by displaying readings. Other programs may then be entered as desired.

6. As an example of PROGRAM 2 operation, assume that readings on the 0.2VDC range are being made. If the displayed readings continuously or intermittently hop around, the filter should be turned on to minimize these effects. Note that operating the Model 192 with the filter on will increase the response time to sudden changes in input level: if short settling times are required, the operator should use PROGRAM 2 to disable the filter. See figure 4-2 for the response graph of filter 3.

5.6 PROGRAM 3. OFFSET/SCALE

PROGRAM 3 allows the operator to automatically multiply normal display readings IX) by a constant (St and add an offset (b). The result (YI will be displayed in accordance with the formula, Y = SX + b. Upon power up, S = 1, and

b=O, but these constants may be changed at the appropriate point in the program. Note that Range, Function, end Zero buttons are inoperative during the course of the program. If one of these buttons is depressed while PROGRAM 3 is running, an “in Pro” message will be displayed. PRO-

GRAM 3 is useful when slope calculations are required for a

series of measurements. Operating instructions for PRO-

GRAM 3 are as follows:

1. Select the Function and Range, and enable the Zero, if desired, before PROGRAM 3 is entered. These operating controls cannot be used once the program is run.

2. Press PRGM. The Model 192 will respond with the program prompt message 8s follows:

3. Press 3. The program number will be displayed for K second es follows:

The instrument will now prompt the operator to enter the

S constant by displaying the following message for ‘h second:

[]

The old value of S will then be displayed: the most signifi-

cant digit will show a blinking “c” segment to indicate that en operator entry is required. If no changes in the displayed value are desired. the constant may be entered by depressing the ENT button.

A new value for S may be entered by depressing the numbered buttons in the desired sequence. Note that S must be in the range -1.999999 L S L +1.999999. After the desired value of S is shown on the display, the constant must be entered into the program by depressing the front panel ENT button.

After the S constant is entered, the Modal 192 will prompt the operator to enter the b constant by displaying the following message for % second:

The display will then show the presently stored value of

b. In addition, the first digit “c” segment will blink, indicating the instrument is waiting for an input. At this point, the old value of b may be entered simply by depressing the ENT button.

A new value for b may be entered by depressing the

numbered buttons in the desired sequence. Note that the b must be in the range of -1999999 (b ( + 1999999 with the decimal point automatically placed according

to range. For a given range, the value of b cannot exceed the maximum that can be measured on that particular range. For example, the maximum value of b on the 20VDC range is f 19.99989. Once the desired constant is shown on the display, it may be entered into the

program with the ENT button.

10. Once the ENT button has been depressed, the Model 192 will show the value of Y. If the value of Y is larger then can be handled by the particular range, an “DFLO” message will be displayed, indicating the instrument must be switched to a higher range. Note that PROGRAM 3 must be cancelled with PROGRAM 6 before the range can be changed.

11. While still in PROGRAM 3, new values for S and b may be entered by using the RECALL button. The following message will be displeyed.for X second:

? r ,I, 3

The Model 192 will then prompt for new values of S and b es previously described. To enter new values. follow the procedure in steps 5 through 9 of paragraph 5.6.

12. The values for S end b will be stored within the Model

192 until the power is turned off. These constants may be used in future runs of PROGRAM 3. Note, however, that the value of b is scaled according to the range in use. If, for example, s value of 19.00000 was entered for b with the instrument on the 20V range. the value of b will be changed to 190.0000 if the program is entered with the instrument on the 200V range.

13. An example of readings that will be obtained when PRO. GRAM 3 is run is shown in the following. Each of the obtained values for Y assumes the following constants:

S = + 1.5; b= +5. Also, the instrument is on the 20 IDCV, ACV. kfll range.

Normal Reading

+8 VDC

-5 VDC

PROGRAM 3 Reading IY = SX + bl

+ 17 VDC

-2.5 VDC

6.3 VAC’ 14.45 VAC AkR

11 kR

‘Requires AC Option

NOTE

The display resolution mode determines the number of digits required for the b and S constants. The range end example values given assumes the Model 192 is being operated in the 6X digit mode. One less digit is required for these constants when in the 5K digit mode.

5.7 PROGRAM 4. PERCENT DEVIATION This program allows the user to determine how much a par-

ticular reading differs from some desired value. The percent deviation is internally computed according to the following formula:

Y=X-n xl00

where X is the normal reading, Y is the percent deviation, end n is the constant to which the reading is to be com-

pared. Upon power-up, n = 0 and must be changed by the operator or the instrument will go into overflow when the program is run. Note that the Range, Function, and Zero buttons are inoperative when in this program; the program

must be cancelled if these parameters must be changed.

The basic procedure for using PROGRAM 4 is as follows:

1, Select the Function and Range, and Zero the instrument,

if desired, before entering the program.

2. Press PRGM. The instrument will display: (i’

3. Press 4. The program message will be displayed for K second as follows:

The instrument will prompt the operator to enter the con-

stant n for ‘h second es follows:

The present value of n will then be displayed. At this

point, some constant must be entered if the present value of n = 0, or an overflow will occur. If the present value of n is not zero, the ENT button may be used to enter the presently displayed value of n into the program.

If a new value of n is desired, enter the number one digit

6. at a time into the display. The value of n must lie in the range of -1999999Ln < + 1999999. Note that the decimal point will automatically be placed according to range. The value of n cannot be greater then the range currently being used. For example, the maximum value of n on the ZOOVAC renge is 199.9999. Also, the

number of digits in the constant depends on the display resolution. In the 5% digit mode, one less digit will

appear in the constant.

Once the desired constant is in the display, the value

may be entered into the program with the ENT button. Once n is entered, the display will show the per-

cent

-199.9999yY c +199.9999. Once again, the actual number of dig& will depend on the display resolution; the least significant digit will be rounded off in the 5% digit mode.

If the range of the instrument is exceeded on the per-

9. cent deviation computation, the Model 192 will display

its “OFLO” message’.

10. A new value for n may be entered without exiting the program by pressing the RECALL button. The instrument will respond with:

for ‘h second, followed by:

deviation

within the range of

r?zTTl

h I 41’

for ‘/ second. The current value of n is then displayed; the user may then enter some other value es described in

paragraph

11. As an example of how the Model 192 computes percent deviation, assume that the display shows e reading of

+ 150V IX) on the 200VDC range and the value for com-

parison (n) is + 125V. The percent deviation Y will be

automatically computed by the instrument when PRO-

GRAM 4 is entered after the value of n lin this case

+ 125) is entered, es follows:

In this example, the percent deviation is positive because the measured voltage (XI is more positive than the comparison standard (nl. If the percent deviation shown in the display should have e negative value, then the measured voltage is more negative than the programmed constant.

5.8 PROGRAM 6. MINIMAX PROGRAM 5 allows the operator to automatically store the

minimum and maximum readings that occur while the pro-

gram is being run. An example of an application for this program might be to monitor the output voltage of a new power supply design to see how much it drifts over a given period of time.

Operating instructions for PROGRAM 5 are as follows:

1. Select the Function and Range, and Zero the instru-

ment, if desired, before entering the program. These

paremetere cannot be changed once the program has

been entered.

2. Press PRGM to obtain the following prompt:

3. Press 5. The instrument will display the program number

for ‘h second es follows:

4. Immediately following the program number, the follow-

ing message will be displayed for ‘h second:

5. The display will continue to show the present reading.

Minimum and maximum readings are automatically stored for recall. The stored date always contains 6% digits even if the storage was made while the unit is in

5.7 steps 5 through 7.

X-n

Y=-x100

”

Y=FE!x,oo

125

Y=20%

F’ I- c, ‘5

5-6

the 5% digit mode. Thus, 6% digit resolution may be obtained for the high and low readings regardless of the display resolution. To obtain 6’% digit resolution for

recalled readings, the instrument must be in the 6%

digit mode.

6. To display the high and low readings, depress the RECALL button: the instrument will display the follow. ing for K second:

7. Following the program number, the following will be displayed for % second:

[:31

This message will be followed by the low reading itself.

8. To obtain the high reading, depress the RECALL button again. The instrument will respond with:

Elapsed

Time

1 hr. 2 hr. 3 hr. 4 hr.

5 hr. 6 hr. 7 hr. 8 hr.

Actual

Voltage

+ 12.006V

+ 12.01v

+ 12v

+11.99v

+ 11.987V

+11.95v

+ 12v + 12.OOlV + 12.005V

At the end of the prescribed time period, the operator could check for low and high values by depressing the

RECALL button. The low value. which will be displayed immediately after the “LO” message, is + 11.95V while the high value for this example is + 12.01OV. To cons tinue the test with the existing high and low values. the operator must press the ENT button. To enter new high and low values, the program must be started from

rhe

beginning.

[h’l

for a period of % second, after which the display will show the highest reading obtained during the current PROGRAM 5 run.

NOTE

The low or high reading sequences will be cancelled if the operator attempts to run

PROGRAM 1 or 2 while reading back low

and high values.

9. To continue the program with the current high and low values, press ENT. The instrument will begin at step 5.

paragraph 5.8.

10. To continue with new high and low values, the program must be entered from the beginning at step 2 of paragraph 5.8.

11. As an example of PROGRAM 5 operation, assume the Model 192 is to be used to monitor the drift of a

+12VDC (nominal1 power supply over an eight hour period. Once the instrument is connected to the supply, the operator would then set the unit for 20VDC operation with the appropriate front panel buttons. The filter, resolution, and Zero modes, may be selected as desired.

To begin the program, the user depresses the PRGM and 5 buttons in sequence; the Model 192 then begins storing maximum and minimum vslues. Assume the power supply voltage actually drifted as shown in the following:

5.9 PROGRAM 6. HI/LO/PASS PROGRAM 6 allows the operator to set low and high

reading limits into memory. Once the limits are sat. the

Model 192 will indicate whether or not a specific reading

falls within the prescribed range. This feature is especiallv useful for component evaluation, where certain component tolerances must be observed. Once the limits are programmed into the instrument. the operator need only watch for the appropriate message on the display to determine if a particular component is within tolerance. With the optional

Model 1923 IEEE-488 interface installed. the Model 192 may

be used to control sorting and handling equipment with suitable relays. Operating instructions for PROGRAM 6 are as follows:

1. Select the desired Function and Range, and Zero the I”strumant. if desired. before entering the program. These parameters cannot be changed once the program is run.

2. Press PRGM. The following message should be displayed:

I:-]

3. Press 6. The instrument will display the program number for % second:

4. Immediately following the program number. the instrument will prompt for the low reading limit with the following message for X second:

At this point, the display will show the old value. If the displayed value is to be used, press the ENT button.

If a new value is to be entered. press the numbered but-

tons in sequence. The low value must be in the range

-lSSSSSS~LDL= ‘+ 1999999; the decimal point will be placed according fo range. Note that the low value cannot be numerically larger than the limits of the range being used.

Once the desired value is shown on the display, press

ENT to enter the low limit.

The instrument will now prompt for the high limit by

8. displaying the following message for ‘h second:

The old high limif will be displayed, and may be entered

9. by simply pressing the ENT button at this point. Note that the high limit must be more positive than the low limit, or the program will not run.

To enter a new high limit, use the numbered buttons in

the desired sequence. The value must be in the range of

-19999993 tilLi + 1999999, with the decimal point placed according fo range. As with the LOL constant, the high limit constant cannof have a value larger than the limits of the range in use. Once the desired value is

in the display, press the ENT bunon to enter the constant.

At this point, the instrument will run the program. No numeric readings will be displayed. bur the instrument will show one of the following messages, depending on the measurment.

A. If the measured value is less than the low limit, then

“LO” will be displayed.

8. If the measured value is greater than the high limit, then “HI” will be displayed.

C. If the measured value falls within the low and high

limits, then “PASS” will be displayed.

To enter new low and high values, press the RECALL

button and begin at step 4 of paragraph 5.9.

As an example of PROGRAM 6 operation, assume that a batch of 10kR. 10% resistors must be checked for tolerance. Before running the program, the operator would place the Model 192 on the 20kR range to make the necessary measurements. Then PROGRAM 6 is run

by depressing the PRGM and 6 buttons in sequence. When the instrument prompts for the low value, the operator would key in 9.000 (lOk0 -10%). When the high limit is asked for, a value of 11.000 is entered (10kR

+ 10%). When the program is run, the instrument will show the “PASS” message for all resistors thaf fall within the 10% tolerance range. For those resistors with values under SkR. the intrument will show a “LO”

message, while resistors greater than 11 k0, will cause

the “HI” message to be displayed.

Three open collector outputs for HI. LO, and PASS, are available on the IEEE card. These outputs may be used

with relays to control other equipment. For further details, consult the Model 1923 Instruction Manual.

5.10 PROGRAM 7. DATA LOGGER PROGRAM 7 is designed to allow the operator to store up to

100 readings in an internal buffer. The reading intervals may be sef to specific values between 0.11 seconds and one hour. At any point in the program. readings may be recalled from the front panel. This program is useful for such applications as the long farm monitoring of the operation of a system. Once the data points are stored, the readings may be recalled to determine if the system operated in the HI/LO limits over the specified period. The operation of PRO-

GRAM 7 is ss follows:

Select the Function and Range. and Zero the insfrument, if desired. These parameters cannot be changed once the program is entered.

Press PRGM. The following message will be displayed:

Press 7. The program number will be displayed for ‘/

second:

The instrument will now prompt the operator to input the time interval constant r. by displaying the following message for K second:

The display will then show the current value of r. Each digit corresponds to a given time interval as listed in Table 5-2. Also shown is the total time required to store

100 readings. Upon power-up, r= 0, corresponding to a

time interval of 0.11 seconds for 60Hz operation.

To enter the old value of r, press the ENT button.

A new value r may be entered by depressing the appropriate number button. Once the desired digit is shown in rhe display, the value will be entered into the program by pressing the ENT bunon.

At this point, the Model 192 will not yet begin to store

8. readings: instead, present readings will be displayed, with the following message appearing every few seconds.

To actually begin storing readings, press the ENT button again. The instrument will respond by logging data

points at a time interval determined by the previously programmed value of r.

The readings may be retrieved at any time during the

logging process by pressing the RECALL bunon. The

number of the reading will be indicated by the following message:

The asterisk represents the number of the reading, which will be displayed for !4 second, followed by the reading itself. Note that the decimal point stops flashing when the display shows a recalled reading.

11. After all 100 data points have been logged, the instrument will respond with the following message:

12. Pressing the RECALL button at this point, will display the last reading in the buffer.

13. To continue recalling readings, press the RECALL button momentarily. After the number of each reading is

briefly displayed, the reading itself will be shown. If the RECALL button is held in, the reading numbers

automatically increment in sequence.

14. To decrement the reading numbers rather than in-

crement them, press the minus l-1 button before depressing the RECALL button. The reading number will continue to decrement with each operation of the RECALL button until the minus button is pressed a second time.

15. Logging may be continued if previously interrupted by

pressing the 0 and ENT buttons in sequence. The decimal point will again flash. To change the reading time intewal or start the program over, exit the program by using the PRGM button and begin at step 3 of

paragraph 5.10.

16. As an example of PROGRAM 7 operation, assume it is

desired to monitor the power line voltage for a computer system over a given period of time. To do so, the

operator would switch the Model 192 to the 200VAC’ range and connect the instrument to the power line.

Once the program is entered, the operator may choose any time interval listed in Table 5-2. For this example, assume that a time interval of 10 minutes is desired. When prompted to do so, the operator should key in a

value of 7 for the constant r. Once the program has run. the Model 192 will log the power line voltage at 10 minute intervals. The instrument may be interrupted at any time to display stored readings. Once all 100

readings are stored the “b FULL” message will be displayed. and the operator may display the readings in

sequence with the RECALL button, as previously described.

Table 5-2. Data Point Times

Total Time For

(

1 2 3 4 5 6

; 9

tFastest reading rate of each function IDCV. KR or ACVI.

5.11 IEEE BUFFER OPERATION”

If desired, the data in the buffer may be read by commands given over the IEEE-466 bus. However, controller must not send the IEEE-486 REN (Remote Enable) command, or the Model 192 will exit PROGRAM 7.

If desired, data in the buffer may be fed to an IEEE listener such as a printer. For more complete information on accessing the buffer through the IEEE bus, refer to the Model 1923 Instruction Manual.

5.12 PROGRAM 6. SERVICE PROGRAM

As the name implies, this program is designed to aid in servicing the Model 192. It is not intended for operator use: qualified service personnel should refer to section 6. paragraph 6.4. for a complete description of PROGRAM 6 operation. Should the operator inadvertently enter this program, operation of the instrument may be restored by depressing any front panel button (except POWER1 four times in succession.

.ll sec.1

,126 sec. .5 sec. 1 sec.

5 sec. 10 sec. 1 min. 5 min.

10 min.

30 min.

1 hr.

For software level E7 use Program 0 for the set-

vice program.

100 Data Points 11 sec. at 60Hz/

12.6 sec. at 50Hz 50 sec.

1 min. 40 sec.

8 min. 20 sec.

16 min. 40 sec. 1 hr. 40 min.

8 hr. 20 min.

16 hr. 40 min. 2 days 2 hr. 4 days 4 hr.

NOTE

* Requires AC option.

** Requires Model 1923 IEEE-466 option

5-s/5-10

SECTION 6

PERFORMANCE VERIFICATION

6.1 INTRODUCTION Performance verification is recommended upon receipt of

the instrument, to ensure that no damage or misadjustment

has occurred during transit. Verification may also be per-

formed whenever the instrument’s accuracy is questioned

or following calibration.

NOTE

For instruments that are still under warranty

(less than 12 months since date of shipment), whose performance falls outside specifications at any point, contact your

Keithley representative or factory

immediately.

6.2 ENVIRONMENTAL CONDITIONS All measurements should be made at an ambient tempera-

ture within the range of la0 to 20°C 165O to 62OF) and a mletive humidity of less than 80%.

6.3 RECOMMENDED TEST EQUIPMENT Recommended test equipment for performance verification

is listed in Table 6-l. Alternate test equipment may be used.

However, if the accuracy of the alternate test equipment is not at least four times better than the instrument’s specifica-

tions, additional allowance must be made in the reading’s obtained. Some of the equipment listed in Table 6-l is not four times better than the Model 192 specifications because such equipment is not readily available. In these instances.

the verification procedures indicate the equipment manu-

facturer’s specified uncertainty in determining the allowable

reading for the Model 192.

Table 6-l. Recommended Test Equipment for Performance Verification

6.4 INITIAL CONDITIONS Before beginning the verification procedures, ensure that

the instrument meets the following conditions:

1. If the instrument has been subjected to extremes of temperature, allow sufficient time for internal temperatures to reach normal operating conditions specified in paragraph 6.2. Typically, it takes one hour to stabilize a unit that is 10°C IlWF) out of the specified temperature range.

2. Turn the Model 192 on and allow it to warmp up for IWO hours.

WARNING

This procedure requires high voltage and Is intended for “se by qualified teat

personnel only. Take care to prevent contact with live circuits which could CBUI)B electrical shock resulting in injury or death.

6.5 PERFORMANCE VERIFICATION

6.6.1 DC Voltage Accuracy Check l2OV to 12OOV ranges)

1. Select the DC Volts function.

2. Connect the DC calibrator (Item A. Table 61) to the

Model 192’s DCV terminal.

3. Select the 20 range.

4. Apply a positive lO.OOOOVDC to the Model 192. The

reading must be within the limits specified in Table 6-2.

5. Select the 200 range.

ITEM

A DC Calibrator

9 AC Calibrator

D Decade Resistor

DESCRIPTION

High Voltage Amplifier 1ooov lUsed with Model 745A)

Kelvin-Varley Voltage Divider IUsed with Model 343Al

SPECIFICATION

1ov. 1oov. 1ooov

*o.ooz% or zopv

O.lV. 1v. 1ov. toov

* 0.022%

* 0.04%

190ll. 1.9kfl. 19kg.

190kn. 1.9MR. 1OMn

iO.Ol%

.19V. l.SV with Fluke .Zppm Terminal

Linsariw

MFR. MODEL

Fluke 343A

H-P 745A

H-P

ESI RS725

746A

720A

6-1

6. Apply a positive lOO.OOVDC to the Model 192. The reading must be within the limits specified in Table 6-2.

7. Select the 1200 range.

WARNING

The 1200 range will overrange at vcltages war 1200V. As specified on the front panel beneath the DCV button,

1.2kV is the maximum allowable voltage that can be applied without damaging the instrument.

8. Apply a positive lOOO.OOVDC to the Model 192. The

reading must be within ths specified limits in Table 6-2.

9. Repeat all checks with negative voltage. Table 6-Z. DC Voltage Performance Check IZOV to

1200v Range

6.6.2 DC Voltage Accuracy Check L2V to 2V ranges)

1. Select the DC Volts function.

2. Select the .2 range.

3. Connect the DC calibrator (Item A, Table 6-11, KelvinVarley voltage divider (El and Modal 192 as shown in

Figure 8-l.

4. Set the DC calibrator to an output of + lO.OOOOV. Sat the Kelvin-Varlev to .019000 lfor an output voltage of .190000 Wltsl.

5. Dial the Kelvin-Varlay voltage divider to zsro. Than press the Model 192 ZERO button for a display indication of

00.0000 f 1 digit.

6. Verify that the Model 192 reading is between .189975 and .190025. Note that the allowable reading includes a

i6 digit allowance for the uncertainty of the DC

calibrator and Kelvin-Varley voltage divider.

7. Repeat steps 4 through 6 with a negative voltage, and be sure to rezero.

8. Select the 2 range. Set the Kelvin-Varley voltage divider to .lSOOOO output. Be sure to rezero.

9. Verify that the Model 192 reading is between 1.89981 and 1.90019. Note that the allowable reading includes

*4 digits for DC calibrator uncertainty.

10. Repeat Step 9 with negative voltage. Be sure to rezsro.

Figure 6-l. Test Circuit .2mV and 2V

6.5.3 AC Voltage Accuracy Check (With Model 1910 AC Voltage Option Installed1

1. Select the AC Voltage function.

2. Connect the AC calibrator (Item 8, Table 6-l) to the

Model 192 ACV terminals. Sat the AC calibrator to 1kHz.

3. Set the Model 192 to the 2 range. Apply l.OOOOOVAC to

the Modal 192. Verify that the reading is within the limits specified in Table 6-3.

4. Repeat steps 2 and 3 for the 20V range and then 200V range. Apply the required voltages listed in Table 6-3 and

verify that the readings are within the limits specified.

5. To check the 1OOOV range, connect the High Voltage Amplifier (Item C) to the output of the AC calibrator per

the manufacturer’s instructions. Select the 1OOOV range

by prassing the 2000 button of the front panel. Connect the amplifier output to the Model 192 ACV terminals. Set the AC calibrator for an amplifier output of lOOO.OOV at

1kHz. Verify that the Model 192 reading is within the

specified limits in Table 6-3.

6. To check accuracy at 50Hz. 2OkHz. and 100kHz. select the 20 range, apply the voltage specified in Table 6-3 at 50Hz, then repeat at 20kHz and 1OOkHz. Verify that the

Model 192 readings am within the limits specified.

Table 6-3. AC Voltage Accurscy Check

I T Range

Applied Voltage

Allowable Readings

at 160 to 26OC

at 1kHz

2ov

2oov

1ooov

1 .ooov 1o.ooov 1oo.oov 1ooo.ov

.99868 to 1.00132V

9.9868 to 10.0132V

99.868 to 100.132V

998.00 to 1002.OOV

at 50Hz

2ov

1o.ooov

9.9868 to 10.0132V

at 20kHz

2ov

1o.ooov

9.9868 to 10.0132V

at lOOkliz

2ov

1o.ooov

9.90 to lO.lOV

For performance verification of TRMS AC volts, refer to the Model 1920 Instruction Manual.

6.5.4 Resistance (!I) Accuracy Check

1. Select rasistancs In) function NOTE

The .2kO and 20kR range performance

verification will be done on four-terminal

ohms, that is, utilizing the fl terminal as well as the fl sense terminal. For four-terminal measurements, connect the 0 sense leads to

6-2

the circuit to be measured and the 0 sense terminals to the Model 192. This arrangement eliminates the error clue to the voltage drop across the current-carrying leads. The

ZERO button also accomplishes this. It is

recommended that both be used to compen-

sate for lead resistance.

2. Perform Zero function as follows: A. Connect the Dls) terminals together (short them)

with a low thermal shorting plug.

B. Press the ZERO button and verify each We) range as

specified in Table 6-4.

Table 6.4 Zero Readings

Range

.2 kR

2 kR

20 kn

200 kR

2000 kR

20MR

3. Select the .2kR range.

4. Connect the decade resistor (Item D, Table 6-l) to the R terminal and the R sense terminals.

5. Set the decade resistor lltem D, Table 6-l) to zero and compensate for any residual lead resistance by pressing the ZERO button for a display indication of .OOOOOO

* .OOOOOl flashing.

Allowable Reading

.OOOOO * 10 digits

0.0000 f 2 digits

00.000 * 2 digits

000.00 i 2 digits

0000.0 * 2 digits

00.000 * 2 digits

Sat the decade resistor to O.lSOOOOkR. Verify that the reading for the .2kR range is within the limits specified in Table 6-5.

Select the 2k0 range.

Set the decade resistor to 1.90000kR. Verify that the reading is within the limits specified in Table 6-5.

Select the 20kQ range. Set the decade resistor to zero

and reset the ZERO button.

10,

Set the decade resistor to lS.OOOOkQ. Verify that rhe

reading is within the limits specified in Table 6-5.

Select the 200kfl range and remove R sense leads. Set the decade resistor to zero and reset the ZERO button.

12.

Set the decade resistor to lSO.OOOkR. Verity that the reading is within the limits specified in Table 6.5.

13. Select the 2000kn range. Set the decade resistor to zero and reset the ZERO button.

14. Set the decade resistor to 1900.00kR. Verity that the reading is within the limits specified in Table 6-5.

15. Select the 20MR range. Set the decade resistor to zero and reset the ZERO button.

16. Set the decade resistor to lO.OOOOMR. Verity that the reading is within the limits specified in Table 6-5.

Table 6-5 Resistance Accuracy Check

Range

.2 kg

2 kn

20 k0

200 kg

2000 kn

20Mfl

‘Manufacturer’s specified uncertainty of the decade resistor (DI in

digits, This uncertaino, has been added to the specified accurscv Of the Model 192 to obtain the allowable reading.

Resistance

.190000k0 .I99960 to

1.90000kQ 1.69960 to lS.OOOOkR 19.9960 to

190.000kR 199.960 to lSOO.OOkR 1899.60 to

10.0000MR 9.9949 to

Allowable Readings

at 18” to 2E°C

.190040 t 19 digits

1.90040 * 19 digits

19.0040 f 19 digits

190.040 * 19 digits

1900.40 * 19 digits

10.0051 f 10 digits

63%.4

SECTION 7

THEORY OF OPERATION

7.1 INTRODUCTION This section contains circuit descriptions for the Model 192.

Descriptions are also included for the Model 1910 AC Option. A separate instruction manual is available for the Model 1920 TRMS option. The information is arranged

provide a description of individual functional circuit blocks. To facilitate understanding, the descriptions are keyed to accompany simplified block diagrams and schematics. Detailed schematics of the Model 192 and Model 1910 are located at the end of this manual.

7.2 OVERALL FUNCTIONAL DESCRIPTION

The Model 192 isa 6X digit, ~2.000.000 counts DMM with five DC voltage and six resistance ranges Istandard). The

unit has l@ and 1mR sensitivity with 0.00005% resolution.

When the Model 1910 AC Voltage Option is installed, AC

voltages from lo@ to 1OOOV can be measured. The most unique feature of the Model 192 is its’ hybrid Analog-to-

Digital converter which uses both charge balance and single slope conversion techniques. A microcomputer located within the Model 192 controls the Analog-to-Digital conversion process. The charge balance/single slope convsrter feature, along with the internal microcomputer, provides

many enhancements to the DMM’s performance. These enhanced features include:

Extremely High Accuracy

High Conversion Speeds

Quick Settling Times

Reduction in the number of component parts

Non-Linear Digital Filtering

Push button nulling of any on-scale input signal

Automatic 2/4 Terminal Ohms Measurements

These items will be described in more detail in the latter part of this section. Refer to Figure 7-1 for a simplified signal flow block diagram of the Model 192.

The Model 192 is partitioned into two electrically isolated sections, digital and analog. These sections are isolated by opt0 isolators and by isolated secondary windings on the power transformer. Partitioning and isolating the unit allows the LO or common input of the DMM’s analog section to be placed at any potential (between + 12OOV1. Simultaneously, the LO or common side of the digital circuitry can be maintained at voltage potentials within 30V of chaws ground. This isolation simplifies interfacing of the Model 192 with external digital equipment.

Operation of the Model 192 is centered around the AID converter. The converter requires a conditioned analog input for the wide range of DC inputs used, and the conversion of ohms and AC voltages to DC voltages. The A/D

Figure 7-1. Basic Block Diagram

7-l

MULTIPLEXER OUTPUT

) INPUT AMP

BOOTSTRAP AMP

100~1 DIVIDER

+2V CALIBRATION REFERENCE

TH’

nSENSE LO

BOOTSTRAP

VOLTAGE

em--------

+5V

(DIGITAL LOGIC1

L ---------- -I

ONE OF 9 DRIVERS FOR 9 MULTIPLEXING SWITCHING FETS I

7-2

MULTIPLEXING SWITCHING

FETS

Figure 7-2. Simplified Multiplexer Schematic (Refer to Figure 7-l. Block Al

converter also requires various control signals and data pro-

cessing capabilities to perform the A/D ConverSion process and to compute the results. Inputs applied to the Model 192 are switched by the multiplexer. These input signals along with zero and full scale references are systematically switched by the Model 192. Only one signal at a time is allowed to pass through the multiplexer which is then routed to the

Input Amplifier, this amplifier acts as a buffer and is capable of multiplying the output of the multiplier by a gain of one or ten.

The digital output of the AID converter inputs to the microcomputer. Here the results of the AID conversion are computed. and this information is sent to the display circuits of the Model 192. If the Model 1923 remote programming

option is installed, the results of the A/D conversion are sent to this option and will be placed on the IEEE general purpose interface bus.

7.3 ANALOG CIRCUIT DESCRIPTION

7.3.1 Input Multiplexer The Input Multiplexer connects one of nine signals to the

Input Amplifier. (Refer to Schematic 30976Dl. A volts or

Ohms measurement requires several inputs to be connected to the input amplifier. Each input is connected in sequential order. The microcomputer of the Model 192 controls the switching sequence and determines the length of time that sach multiplexer switch is turned on.

Switching of the various inputs and reference signals is acTomplished with nine J-FET transistors (0310. 0311, 0312, D327, 0328, Cl334. 0339, and 0341). A problem is encountered when using J-FET transistors as switches. When the J-FET is turned on, the low to high transistion of the switching voltage causes charge coupling into the analog signal the FET is switching. The effects of these transients

were eliminated by the use of software generated delays.

;lowever, it is necessary to drive the gate of each FET switching transistor with the input signal voltage to turn it on. That is accomplished with a bootstrap amplifier which

operates as a voltage follower. Its input is connected to all

the FET switches; therefore, its output follows the voltage that is selected by whichever FET switch is selected bv the microcomputer.

Gate drives for these FETs are controlled by differential comparators IU321, lJ304. and U3051. The comparators convert logic level signals to voltage levels suitable for turn-

ing off and on the J-FET transistor. To turn a J-FET transistor off, the comparator output transistor pulls the J-FET gate to -2SV (see the equivalent circuit of Figure 7-2). To turn on the same transistor, the comparator’s open collector output transistor turns off. This allows the gate to be pulled to the bootstrap voltage. The bootstrap voltage is virtually the same as the drain voltage of the switching FET. For further information about the bootstrapping process, see paragraph 7.3.5. The following paragraphs discuss the operation of the Input Multiplexer during DC volts, AC volts, and ohms measurements.

1OO:l DlVlDER

c2V CALli3RATlON REFERENCE

- 3ov RANGE

IFULL SCALE)

.2V

cl329

@12OOV INPUT A

Figure 7-3. DC Voltage Measurement

2ov

2oov

2ooov

FRONT

PANEL

SIGNAL

IFULL SCALE1

.zv

2ov

12v

7-3

7.3.2 DC Voltage Measurement In DC volts operation, as shown in Figure 7-3. the input

signal either goes directly to the Input Amplifier or is con-

nected across a 1OO:l attenuator with a total resistance Of

10MO. The attenuation of the DC input signal is determined by the range selected. Three input signals to the A/D con‘verter are required for DC volts operation Le. V,,,, V,,,, ,and V

measu%j’for 16.6 msec (See A/D Converter, paragraph

‘7.3.6). Each digitized value is stored in memory and then

used to calculate a reading by the formula:

It can be seen that the zero error is subtracted from both the signal and the reference, and then the ratio is taken. Multiplication by two is needed because the reference is 2V. In taking a DC reading on the bench, the voltage seen at the high DC voltage input terminal is switched by the associated

FET to the isolating input amplifier. The amplifier then passes the voltage to the converter. which digitizes it and passes it on to the processor which stores it. Next, the zero input FET is turned on and a zero input is processed and stored in the same way. Then the output of the 2V reference

) Each signal is required to the A/D input and

SIGNAL INPUT

0328 “ON”

2V REFERENCE

Figure 7-4. FET Switching Sequence for DC Voltage

Measurement (Bench Mode of Operation)

Figure 7-6. DC Voltage Measurement FET Switching

Sequence (System Mode of Operation)

circuit is processed and stored, and finally, another zero input is similarly processed. The lest zero is necessaw because the gain in the input amplifier is switched resulting in a different offset voltage. When all four inputs have been obtained, the processor calculates a reading, and displays it.

Each switching FET is allowed to stay on for a period of time and then turned off before proceeding to the next step in the flow chart (Figure 7-41. The “ON” time for each FET is

controlled by the Model 192’s microcomputer.

Range switching of the input signal from the 200mV, 2V or 20V range to the 200V and 1kV range is accomplished via

relay K301. The relay is controlled by a 3 to 8 decoder

(U3221. Decoding is a function of the Shift Registers of the

Al D control logic. The relay decoder is also used to select

ranges for the AC Voltage option.

In system operation, a DC voltage reading is obtained in a slightly diierent manner to get faster results. In the OneShot mode, the meter continuously multiplexes, digitizes. and stores zero and calibration inputs until a measurement triggers Occurs and the input from the high terminal is

digitized. The processor can then produce a reading much faster then it would using the bench method.

During system operation a WAIT command can be used. A “Wl” command programs the Model 192 to turn on 0328

for 14ms (Default condition). A “WB” command turn on Cl328 for 4ms. The modes are only recommended for AC voltage source resistances of less than 100kR.

7.3.3 Resistance Measurement For resistance measurements, four inputs are required so

the Model 192 can obtain a reading by means of a ratiometric technique. The required inputs are:

Ohms Reference HI

Ohms Reference LO

Ohms Sense HI

Ohms Sense LO

The ratiometric technique is a mathematical process that compares numbers and then derives a ratio from them. In the Model 192 the ratio is a voltage ratio that is created by a common current flowing through two resistors in series. The current passes through both a known reference resistor and the unknown resistance. The current through both resistors can then be determined by measuring the voltage drop across the known resistor and then calculating the current. Once the current through the unknown value resistor is calculated and the voltage drop across it is measured, the unknown resistor’s value can then be calculated

Five FET switches lC1301, Q302, D303, Cl306. and Q3081

select one of five known value resistors (see Figure 7-6).

Each of the resistors is associated with a specific ohms range. The resistor selected by the FET switches is equal to one half of the full scale range. For example, a 10k known value resistor is used on the 20k range. and a 1OOk resistor is used on the 200k range.

The voltage across the selected range resistor appears at

0310 #lEF HI) and Cl333 IREF LO). The voltage across the unknown resistor appears at Q334 (SENSE HII and Cl339 (SENSE LO). An ohms source voltage of -4OOmV is used on the .2k ohm range, and -4V is used for all other ohms ranges. As mentioned earlier, four input signals are required for ohms measurements. Each signal is measured for

16.6msec. The signals are converted to a digital number and stored in the microcomputer of the Model 192. The microcomputer then calculates the measured value using the formula:

It can be seen that IReEF &(RREF LoI is the voltage across the known resistance and that IQ,,,,, “,I - (RSENsL Lo1 is the voltage across the unknown resistor.

KNOWN

Figure 7-6. Resistance Measurement Simplified Circuit

7-5

Switching for Ohms operation is shown in the flow chart

(Figure 7-7). In taking an ohms reading, the voltage seen at the OSENsE.H,, !erminal is switched by 0334 to the input amplifier, dIgItwed, and stored in memory. Next, the ohms

SENSE LO FET (0339) is turned on in the same manner. Then the voltage at the ohms REF LO terminal is processed and stored, and finally the ohms FIEF HI input is similarly

processed. When all four voltage inputs have been obtained, the processor retrieves the stored values. performs a calculation for the precise reading, and displays the value.

II SENSE HI

Q334 “ON”

R SENSE LO

(1339 “ON”

i, REFERENCE LO

(1333 “ON”

R REFERENCE HI

Q-310 “ON”

“II

FRONT PANEL CONN.

Figure 7-8. Affect of Lead Resistance in Z-Terminal

Ohms Measurements

For 4-terminal measurements, the R SENSE leads are connected to R, and the effect of lead resistance can be

calculated as shown in Figure 7-9. It can be readily seen why the stated accuracy for the 200kR range requires that the effect of lead resistance be cancelled with the ZERO push button for both Z-terminal and 4-terminal measurements.

FRONT

PANEL

CON.

“RI

RI HI

“Cl

AiD INPUTS

“1) REF HI

A/D INPUTS

V,,REF HI

Figure 7-7. FET Switching Sequence for Ohms

MeeSUrement

Up to this point, the effect of lead resistance on the resistance measurement has not been considered. As shown in Figure 7-8, lead resistance can affect the display ohms reading in both Z-terminal or 4-terminal measurements. For this explanation, resistance of the test leads have been designated as Rl-174. If SENSE HI and LO terminals are not connected to R,. the sensing occurs at the HI and LO input terminals through resistors R, and the displayed reading includes the resistance of Rl and R4 added to the unknown (R,I.

7-6

“RX MEASURED= “x ACTUAL

x “RI x 4

R,+Rs

‘b4SE x x ‘4

with R, = 10, snd ~~ z 1OOkR

Figure 7-9. Affect of Lead Resistance in 4-Terminal

Ohms Measurements

7.3.4 AC Voltage Measurement

7.3.5 Input Buffer Amplifier

In AC Volts operation, the Model 1910 AC Voltage Option is installed between the AC input terminal and the Input Amplifier (see Figure 7-10). The Model 1910 converts the AC input voltage to a DC voltage between zero and -2”. On other than the 2V range, the input signal is divided by 10,

100, or 1000 depending on the range selected. For AC voltage measurements, four input signals to the AID converter are required. Each signal is measured for 16Bmsec and ita digitized value is stored in memory.The microcom-

puter then calculates a reading using the formula:

“,, = 2lV,,HI -V,,AUTO ZERO1

~“REF-“mlo)

Where V,,HI is the Model 1910 ouput, V,,AUTO ZERO is its DC offset, V ground. The 2 YErequired because of the 2v reference.

Since AC volts is a four phase measurement, the maximum

conversion rate for AC volts is two readings/second.

Switching for AC volts operation is shown in the following flow chart (Figure 7-111. In taking so AC reading, the voltage seen at AC HI is switched by Cl311 to the input amplifier. The voltage is then processed and stored in the same manner as described for DC Volts and Ohms operation. Next, the AC auto zero FET 10312l is turned on and the voltage seen there is processed and stored. The processor then retrieves the stored voltages, calculates a reading, and displays it.

is the 2V reference, and V eO is signal

The Input Buffer (Figure 7-12) is a non-inverting low noise,

high input impedance amplifier which looks at each input with either Xl or X10 gain. Its output is capable of voltage swings of *ZOVDC. These parameters era beyond the cap-

abilities of a single op amp. Two op amps, one having high

input impedance/low noise characteristics IU301 I and the

other having a wide output voltage swing (U303). were

combined to produce the desired characteristics. A third

operational amplifier, U302, operates at unity gain. Its sup-

plies are bootstrapped to the input to *6V via zener diodes

VR301 and VR302 and emitter followers 0314 and D315.

This bootstrapping technique centers the 2 V8 supplies

around the input potential of U301. U301 can then handle

input signals up to f 20” while providing linear operating

characteristics.

If the input amplifier had to provide only unity gain. this arrangement would be adequate; however, on the 0.2” and 2V ranges a gain of ten’s required. Operational amplifier

U303 supplies the outer capability for the 120” output swing.

7.3.6 AID Converter A simplified schematic of the A/D converter is given in

Figure 7-13 and its waveform is shown in Figure 7-14. In

operation, the output of the input buffer is applied to the

Transconductance Amplifier. This amplifier provides two functions. It converts the input voltage to a current, which

Figure 7-10. Block Diagram AC Volts Operation

7-7

ACAUTOZERO

and D, is enabled by C+ going low again. fq goes high and

removes the clear from U314A.j Up to this point, Its was

turned on for one clock cycle lZ*ec) and then turned off.

The earliest it can be turned on again is one clock cycle

later. Each time Its is turned on, a counter is incremented by an inverted V-F PULSE from 4. The flip-flops divide the clock frequency by two, limiting the maximum number Of

charge balance integrations and output counts to one half of the clock frequency (240kHzl. In the precise 18,6msec charge balance period, the maximum number of times that E2 can go

16.6msec x 240kHz = 4000 counts. Table 7-1. Settling Delays, SN on to Turn On of

high

Integrator

and be

counted is

2V REFERENCE

Figure 7-11. AC Volts Operation Flow Chart

goes to the integrator when requested, and also provides an

offset current so that its bipolar input voltages are converted to unipolar output currents.

The A/D converter operates first in a charge balance (CBI

phase, and then in a single slope ISS) phase. A 18.6msec interval at 60Hz and 20msec interval at 50Hz were selected to sample each input as the best compromise to achieve good line rejection and relatively fast conversion speed.

A C8 phase is begun when INPUT DISABLE goes low. This occurs at the completion of a delay period that allows the signal to settle after turning on the appropriate input MUX switch. The delay is software generated and is dependent

on the function selected, as given in Table 7-l. When INPUT DISABLE is removed, IIN is connected to the integrator, and V, ramps positive. The D flip-flop then acts as a comparator, providing timing and control. After V, exceeds the D threshold of U314, Q, goes high at the next positive going clock edge. At the next clock edge (negative going), I& goes high and connects Its to the integrator. IcB is greater than Zl,, maximum, and thus, V, immediately ramps negative.

q is also low at this time which resets and holds 0, low. At

the next negative clock edge (1 cycle later). Ice is turned off

JFET

Switch

s2 53 s4

At the end of the charge balance phase, the output of the integrator is resting at some positive voltage. The single slope comparator output is also positive and will not switch

until the integrator output crosses zero. The comparator output is ANDed with a one millisecond pulse in the digital section to produce SINGLE SLOPE ENABLE. This allows Iss to flow into the integrator. A 3.84MHz clock is counted from the time SINGLE SLOPE ENABLE went high until the single slope comparator changes state W, crosses zero).

When this occurs, Iss is shut off and the counting is StOP-

pad. The amount of charge quantized by lss is equal to

111024 of the charge quantized by Its. The microcomputer multiplies the C9 counts by 1024 and adds the SS counts to it to obtain the composite count (4.1 million maximum).

7.4 DIGITAL AND DISPLAY CIRCUIT DESCRIPTIONS

7.4.1 Microcomputer (Refer to Schematic 309750) The microcomputer and its associated logic circuitry provide

timing and control of the Angalog-to-Digital conversion pro-

cess. Additional functions provided by the microcomputer include operation of the Front Panel Display, implementation of Front Panel Programs, and the control of data through the Model 1923 IEEE-188 option.

The microcomputer includes a 6808 microprocessing unit (MPUI, a 6522 versatile interface adapter (VIA), two 2732 read only memories IROMsl, two 2114 access memories (RAMS), an address decoder, a data bus driver (front panel interfecal, and the necessary reset logic. (See Figure 7-15.) The total memory utilized in this system consists of: 8K x 8 bytes of ROM ltwo 4K x 8 PROMs/U129 and U130) for program control, qAM’slU123 and U124) for temporary storage: 8K x 8 bytes

Delays

DC”

1 1

lKx8 bytes of RAM (two lKx4

IlllSfll

AC\

1 1 1 100 1 1

7-a

Figure 7.12. Simplified Input Buffer Schematic (Refer to Figure 7-l. Block B)

Figure 7.13. Simplified A/D Converter Schematic (Refer to Figure 7-1. Block

7-9

- 1e.smsec DELAY’

‘For readout Of UP prB-scB1B counter.

Figure 7-14. AID Converter Integrator Output Waveform

for the IEEE-488 option, end 16 bytes for the VIA lU132) to

control peripherals. Provisions have been made for future memory expansion by including an additional socket on the

mother board to accomodate an additional 4K x 8 bytes of ROM (PROMIU134).

7.4.2 Memory Note that the total memory used I8K of ROM, 1K or RAM,

8K of IEEE-488, and 16K of VIA) is a small portion of the entire addressing capabilities of the 6808 MPU IlJ131 I. The

microprocessor is capable of handling 64Kx8 bytes (precisely, 65,538/E bit words). Memory locations for the

64K addresses are assigned the values 0000,, through

FFFF,,. The ROMs. RAMS, VIA, and Data Bus Drivers (u1281 are each allotted 8K bytes of memory. An 8K byte is reserved for the IEEE-488 option. For example: although

SINGLE SLOPE PHASE

- -

0.5msec

INTEGRATOR INPUT DISABLED -

only 1K of RAM is utilized, an 8K portion or “chunk” of memory is reserved or dedicated for the RAM function. In a similar manner, 8K bytes are reserved for each PROM even though each PROM can store only 4K. 8 bit words. An additional 8K bytes are dedicated to the VIA while only 16 bytes are used. Another 8K memory is reserved for front panel

control (Data Bus Driver, U128l however, these memory locations are never addressed. This will beexplained in the following paragraphs. Finally, an 8K x 8 byte in memory is

reserved for the IEEE-488 option (the option only requires

4K of memory). Refer to Table 7-2 for specific address loca-

tions reserved for the various functions. Note that an 8K

byte Of memory is not assigned (680&7FFFl.

DELAY

- MEASUREMENT PHASE

7-10

Table 7-2. Memorv Byte Locations

Device

Selected RAM IU123, U1241

VIA W132) Buffer (U128)

IEEE-488

PROM W1291

Socket (U134)

PROM W1301

* Dedicated/not necessarily all utilized.

** Not assigned.

I** For future PROM expansion.

*** Never accessed.

MPU Memory

Byte Locations

0000-l FFF

2000.3FFF 4000-5FFF 6000-7FFF

EOOO-9FFF AOOO-BFFF COOO-DFFF

EOOO-FFFF

hItput

Oil

01 Y2 yo

05 Yl

7.43 Address Decoder Interfacing of the microprocessor with the RAMS, ROMS,

Front Panel, VIA or the IEEE-488 option is controlled by the

Address Decoder IU1211. Partial address decoding is used in this system. The 3 to 8 Address Decoder selects one of the seven devices CV, isnot used) listed in the Table 7-2 vis “pper three most slgmfacant lines; A13. A14, and A15. (The Al2 address line of the MPU is not used.1 The seven addresses determine which of the two PROMS are selected: the upper 8K @0& through FFFF,,/U130) or another 8K byte in memory IA000,, through 8FFF,,/U129). Remember, the ROMs memory capacities are only half (4Kl of the addresses allocated for them. Also selected are the two 1 K x 4 RAMS (connected together to provide 1 K x 81. the front panel input, the VIA, the IEEE-488 option bus, and

third PROM, are provided for expansion.

As mentioned in the preceding paragraph, the function

selected is determined by the state of the addresses A13,

A14, and A15.These address lines determine which output is selected at the decoder (U121l in accordance with Table

7-2.0nly one of the devices will have accesa to the DATA

BUS at any time. The address decoder selects one of the devices only after a valid memory address has been asserted at the decoders input IE3). The valid memory address (VMA signal) is generated by the MPU approximstely 200nsec after 02 time. (02 is the MPU’s 1MHz output clock.) This is sufficient time to allow for the address lines to settle. The accuracy of this main timing signal (02) is controlled by a 4MHz external crystal, YlOl; the microprocessor then divides this signal by four.

7.4.4 Reset

U125, U126 and U122 form a “reset” network which

together resets the MPU, VIA, and the IEEE-488 option in

the event the front panel display is not updated after a

specific period of time has elapsed due to a lost program or

power line transient.

The 1MHz timing signal from the MPU (*I?), clocks a 214

(16.3841 stage counter (U1251 whose output conditions a

second counter (U126) to enter a count down mode after a

period of 16.6msec. (lMHz-16,384=60Hz= 16.6msecl. After the 16.6msec A/D integration period has elapsed and display update data is not present at the output of the VIA

lPB5) because of a possible system malfunction, U126 will

continue to count down until Q3 goes low and resets the

system. As long as update data is present at PB5, the VIA

clocks this data into the Display. This same clock pulse

(CA2) inhibits the reset condition. The lead edge of CA2 is

detected at the lead-edge-detector lone-shot/U122A,

U122b, and Cl261 and presets or “loads” a 15 count into U126. It can be seen then, that as long as data is present, a reset will never be generated because the data pulse will continually reload the counter back to 1111 (151 before it has

a chance to count down to 0111 171. Note that 8 CO”nt down

pulses would have to occur for a “reset” which is equivalent t0 eight 133msec AID integration periods with no data pre-

sent. If update display data is not present within this

16.6msec period, 03 of U126 will go low and reset the MPU.

VIA and IEEE-48-w lif present). The system will re-

main reset until RESET returns high.

7.4.6 Front Panel Switch Port Information from the Front Panel function and mode select

tion switches is placed on the Data 8”s (lines D$ through

D4 and D7) through the Data 8”s Driver IU128). The four

inputs to this tri-state buffer (switch port) are routed from the front panel switches. Note that there are only four switch inputs (SW&SW4). The switches are connected in a matrix configuration such that each switch input serves more that one function or range. Although the address decoder has resewed an 8k byte in memory for this device the memory loCations are not accessed or addressed by the

Bus driver. A f&h input to the Data Bus Driver is from the line frequency 50/60Hz detector (0102).

7.4.6 Line Frequency Detector

Q102 and associated components form the 5016OHz detec-

tor. The base of Cl102 monitors the power linelfreqency “IS

R120 which is connected to the secondan, of a power s”p~

ply transformer. The 50 or 60 Hertz signal is squared off and

placed on the data bus. The MPU then determines whether

the line frequency is 50 or 60 Hertz to establish the basic i’l-

tegration period (16.6msec at 60Hzl20ms at 50Hzl. The “no will perform as though the line frequency is operating at 50Hz if the line source is actually 400Hz. This is necessary since 400Hz is sn even multiple of 50Hz; therefore. 8 line

pulses are required to establish the basic integration period at a line frequency of 400Hz (the A/D cannot operate at this speed).

7.4.7 Isolation There is 1500 Volts isolation between the microcomputer

and the AID control logic. Isolation is achieved with fhe “se

of opto isolators AT101 through AT104. AID output data is

isolated from microcomputer by opto isolator AT104.

ATlOl, AT102, and AT103 provide isolation between the

microcomputer outputs P87, C81, CB2, and the A/D con-

trol logic.

7.5 A/D CONTROL The conversion from analog data to digital data begins with

the integration cycle. An integration cycle begins with the appropriate signals to the analog circuiti enabled by one or

more of the Sl through 527 lines going high. These are the

output lines of shift registers, U103/H3 and U104/E5, and

the binary-to-decimal decoder, U105/H4. The three devices serve as output latches. Latch functions are listed in Table 7-3.

7.11

7-12

z: ifi E? z:

SlO Sll s12 s13 s14 s15 S16 s17 S18 s19 s20 s21 s22 S23 S24

525 S26 s27

Table 7-3. Functions of Latch Outputs

Function Pin A input of 4 to 10 Decoder

Pin B input of 4 to 10 Decoder Pin C input of 4 to 10 Decoder

200k Ohms range select

2k Ohms range select

2V REFERENCE multiplex control

Input buffer 1OOOV range control

DC HI multiplex control AC HI multiplex control AC AUTO ZERO multiplex control ZERO multiplex control OHMS SENSE LO multiplex control OHMS SENSE HI multiplex control OHMS REFERENCE HI multiplex control OHMS REFERENCE LO multiplex control

Input buffer Xl control Transconductance amplifier range control

Input buffer X10 control

0.2k OHMS range selectl0HM.s so”rce range select Transconductance amplifier range control

The microprocessor waits for the inputs to settle before

clocking the shift registers. The charge balance phase is initiated when the first stage ICllj of the shift register (UllOl goes high ICB START signal). (See Figure 7.16.) When CB START is “true” the “D” input of the charge balance flipflop, UlOB, and the input of gate U107B are et the logic “1” state. This logic high is gated through and clears the 4 bit divide-by-16 counter (UlOlBl. The next rising edge of the

2.4kHz clock signal sets the flip-flop whose 0 output goes low and enables the integrator by forcing INPUT DISABLE low. The microprocessor waits 16.66msec (the integration period for 60Hz; 20msec or 50Hzi and the charge balance

line returns to.0. At the next rising edge of the 2.4kHz clock,

the0 output of the flip-flop goes high again and disables the

input to the integrator, ending the exact 16.66msec integra-

tion period. Notice that the clock frequencies are crystal

controlled; however, the entire process is actually under microprocessor control at all times.

While the integration period is taking place, pulses (V-F

PULSES) are inputted into the4 bit counter IUlOlBl. When the cwnter overflows after 16 ccwnts occur, clock pulses are generated at its 2Q output which the VIA counts in an internal counter lPBGl.?hese clock pulses become the most significant bits of the result. At the end of a charge balance phase, 4 bits of data are left on the counter. This data is obtained by setting the remainder line to”1” 03 of the shift

IPB7) to pass through gates UlOZl3. U107C to ultimately clock the 4 bit counter. By strobing the counter in this way and waiting for the counter to overflow, the remainder may

be determined. The number left in the counter is equal to 16

minus the number of strobe pulses. This data now becomes the next significant 4 bits of the 24 bit result.

Figure 7-16. Charge Balance Timing

The single slope phase begins when the SS START line (Q2

output of the shift register, UllOl goes high. (Refer to Figure 7.17.) The SS START signal controls the D input of the single slope flip-flop, UlOBB IG21. On the next rising edge of the 3.64MHz clock, the single slope flip-flop is set

7-13

and its Q output is ANDed with the COMPARATOR OUT-

PUT at U107D to generate the SINGLE SLOPE ENABLE signal. In addition, gate U102A is enabled and the 3.84MHz clock pulses are counted et UlOlB in the same manner the V-F pulses were counted in the charge balance phase. The single slope phase ends when the comparator goes to a “‘fl” and gates off the 3.84MHz clock to the counter. The re-

mainder left on the counter is again read es in the charge balance phase. The result is added to the charge balance phase and single slope phase. The result is broken down as follows:

24 BIT RESULT

6 Bits-These 6 most significant bits are accumulated in the

VIA each time the 4 bit counter overflows during the charge balance phase.

4 Bits-This is the remainder left on the 4 bit counter during

the CB phase.

6 Bits-The B most significant bits are accumulated in the

VIA each time the 4 bit counter overflows during a

single slope phase.

4 Bits-This is a remainder left in the 4 bit counter during

the single slope phase.

buffered TTL compatible 3.64MHz clock to UlOlA which

runs the charge balance circuitry within the AID at a 460kHz rate. The 2.4kHz clock is obtained by further dividing the 3.84MHz clock with UlOlA and U106 (see

Figure 7-191. This clock is used to provide en exact

16.68msec (60Hzl or 20msec (50Hzl window and also pro-

vides the interruptions for the microprocessor.

7.6 Display Circuit The display information is outputted on PA43 through PA6

on the VIA (1101 bus. The information is updated at a

1.2kHz rate which means each digit is ON for 633 microseconds. Each update begins by presenting nevv segment information on the VIA (l/O) bus (PA@PAGl and outputting a clock pulse on CA2. The clock pulse inputs to U203 Snd shifts a digit enable bit to the next digit to be

enabled. Every eight times the display is updated, a digit enable bit is generated at PB5 and goes to the enable data

input of the shift register. Refer to Figure 7.20.

The first four digit drivers drive the rows of the switch

matrix. The switches are arranged in a 4 by 4 matrix, thirteen of which are used. The columns of the switch matrix go to Bits N-3 of the front panel switch port described in

paragraph 7.4.5. The segment drivers are 0201-0208. In addition to driving the various segments, they also activate the appropriate LED’s,

Figure 7-17. Single Slope Phase

One of the many functions of the VIA is to transfer data from the digital side to the analog side of the optical

isolators. With the strobe line (PB7) HI, a data transfer starts. One byte of data is stored in the serial register ISR) of the VIA and is automatically clocked through the optical isolators using the clock (CBl) end data (CB2) lines of the serial port. Another 6 bits are clocked out of the VIA. The strobe line (PB71 is brought LO then HI again to shift the 24 bits of data which are shifted into the latches (U103, UllO, U1041. Four of the bits are used to address the binary to decimal decoder (U1051. Refer to Figure 7-16.

7.5.1 Clock Circuit

The 3.84MHz clock is a Pierce oscillator using QlOl as the

gain element and a 3.64MHz crystal YlOl es the feedback

element. LlOl and Cl08 act as a parallel load. RllO, Rlll,

and Cl10 provide appropriate level-shifting compatible with

the TTL input of U107A. The output of U107A provides a

7.7 POWER SUPPLY The power supply for the Model 192 contains the line

voltage fuse (FlOl), switching components, and a discrete current driver. Because of the simplicity of the design, a block diagram is not required (refer to page 2 of Schematic 30975Dl.

The components mentioned in the preceeding paragraph generate the six voltages required for proper operation of the Model 192. St01 is the front panel main power switch. When this switch is in the “ON” position, AC line voltage is applied to the primary of TlOl. 5102 (internally located) conditions the Model 192 for 1lOVAC or 220VAC operation by placing the two primaries in parallel or series,

respectively. Closer observation of the schematic will note that within the

four bridge rectifiers, there are actually six rectifier circuits. CR103 and CR104 are full-wave bridge rectifiers utilizing their own secondaw transformer windings. CR101 and CR102 are dual full wave rectifiers sharing a common center-tapped transformer (e.g. The two diodes at the right in CR101 perform the full-wave rectifier for the +30VDC while the two at the left rectify the AC input for the

-3OVDCI. Notice the similarity in all stages. The components used in the six circuits are listed in Table 7-4 for convenience. All circuits have filters at the outputs of the rectifiers. The raw DC voltages are regulated and then

7-14

bypassed. The + 15V Wllll, the -15V. the +3OV, and the

-30V are developed solely for the Analog circuits. In addition, the Analog circuits have their own + 5V supply (U127J.

The + 5V supply for the Digital Logic has a series pass transistorlhigh current gain network (0103 and Q1041 at the

Table 7-l. Power Supply Component Identification

output of its regulator W133l. CR106 compensates for the

base to emitter voltage drop across (1103. CR105 provides short circuit limiting. Note that this is the stage where the signal tapped off for the 50/60Hz Detector of the Digital

Logic.

Cirrent Amp.

a1031

a104

Figure 7.16. Simplified Schematic of Latch (Refer toFigure 7-1, Block El

Figure 7.19. Simplified Oscillator/Divider Diagam IRefer to Figure 7-l. Block FI

7.15

FROM U-126

0 s209 1 0 s2101 0 s2111 0

s212 1

AUTO ,20m

5 4

FROM U-132

u201

DRIVER

200 200

-4

R203 l-

2000 2000

3 2

SWFT REGISTER

I.-

i-1

PAO-PA7 A

‘Bl

II!

Figure 7-20. Display Schematic (Refer to Figure 7-1, Block Gl

SECTION 8

MAINTENANCE

6.1 INTRODUCTION This section contains information necessary to maintain the

Model 192 DMM and the Model 1910 AC voltage option. Adjustment/calibration, troubleshooting, and fuse replacement procedures are provided. Calibration should be performed yearly (every 12 months), or whenever performances verification (see Section 61 indicates that the Model

192 is out of specification. If any step in the calibration procedure cannot be performed properly. refer to troubleshooting information in this section or contact your Keithley representative or the factory. Complete calibration and

maintenance information for the Model 1920 and the Model

1923 is provided in the instruction manual supplied with the option.

8.2 CALIBRATION The following paragraphs explain the calibration procedure

for the Model 192.

WARNING

This procedure requires the use of high

voltage end is Intended for qualified test personnel only. Take care to prevent contact with live circuits which could ceuse electrical shock resulting in injury or death.

8.2.1 RECOMMENDED TEST EQUIPMENT

Recommended test equipment for calibration is listed in Table 6-l. Alternate test equipment may be used, However, the accuracy of the alternate test equipment must be equal to the specifications in Table 8-1,

8.2.2 ENVIRONMENTAL CONDITIONS

Calibration should be performed under laboratory condotions having an ambient temperature of 23’X + l°C. and a relative humidity of less than 70%. If the instrument has been subjected to temperatures outside of this range, or to higher humidity, allow one hour minimum for the instrument to stabilize st the specified environmental conditions before beginning the calibration procedure.

6.2.3 Warm Up Connect the line cord to an appropriate power source lsee

paragraph 6.3.21 and depress OFF/ON push button to ON. Allow two hours for warm up before beginning the calibration adjustments.

8.2.4 Calibration Adjustments

WARNING

Some procedures require the use of high voltage. Take cere to prevent contact with live circuits which could cause electrical shock resulting in injury or death. Use an insulated tool when making adjustments.

To make calibration adjustments:

1. Apply the appropriate input.

2. Lift off the top cover MOMENTARILY to make the adjustment.

3. When the adjustment is made reinstall the top cover.

ITEM

Table El. Recommended Test Equipment for Calibration

DESCRIPTION DC Calibrator

AC Calibrator

High Voltage Amplifier (Used with Model 745Al

Decade Resistor

Kelvin-Varley Voltage Divider (Used with Model 343A)

SPECIFICATION

19v. 19ov. 1ooov

@20oom

iv, ibv, ioov

220ppm

1OOOV. 400ppm

190fl. l.SkQ, 190k0

1.9Mg. 1OMR

Certified to 50ppm O.lSV, l.SV

with 2ppm Terminal Linearity

MFR. Fluke

H-P

ESI

Fluke

MODEL

343A

745A

746A

RS725

720A

6-l

A. Refer to Table 8-2 and perform the listed adjustments

in the sequence indicated. See Figure 8-l for adjust-

ment locations. Perform steps 1 through 11 to calibrate the basic Model 192. If the Model 1910 AC

voltage Option is installed, also perform steps 12

through 19. If the Model 1920 AC voltage option is installed refer to the Modal 1920 Instruction Manual for calibration instructions.

6. To insure that all functions and ranges ara operating properly following calibration, utilize the performance verification procedure in Section 6.

C. If calibration cannot be accomplished or the perfor-

mance verification procedure indicates a problem, proceed to troubleshooting paragraph 8.3.

8.3 TROUBLESHOOTING SET-UP PROCEDURES The troubleshooting instructions contained in this section

are intended for qualified personnel having a basic understanding of analog and digital circuitry used in a precision electronic test instrument. Instructions have been written to

Table 8-2. Calibration Procedures

itep Function Range Applied Input

1 I R 1 20M 110MKl

n ZOOOk 1900kR

n 200k 190kR n 20k 19kR

R 2k l.SkR n .2k .lSkR

DCV 2v 1.900000v

DCV 2v 0.00000”’

** Coarse Adjustment

*** Connect the DC Calibrator to the Model 192 so that it supplies negative voltage to the Model 132. Set the DC Calibrator

Steps 4 through 6 are to be made with 4.terminals ohm measurement. The instrument must re rezeroed using the 4.terminal low thermal short to establish baseline before gain adjust.

Steps 12 through 19 require the Model 1910 ACV option to be installed in the Model 192. There is no need 10 proceed further than Step 11 if the Model 1910 is not installed.

DCV 2v - 1.90000v DCV 2ov 19.ooooov DCV 2oov 19o.oooov DCV 2ooov 1ooo.ooov ACV 200V 1OOV at 5OkHz ACV 2000V 1OOOV at lkliz ACV 2V 1V at 1kHz ACV 20V 1OV at lkliz ACV 200V 1OOV at 1kHz ACV 200V 1OOV at 50kHz ACV 2V 1V at 50kHz ACV 20V 1OV at 5OkHz

* Steps 8A and 86 must be performed for Rev. D and above Analog Boards IPC-560)

for 0.00000 Volts.

2V Dial Kelvin-Varley Divider

to o.oooooov Depress Zero

Press Zero 0.00000 * 1 digit

assist in isolating the defective circuit or subcircuit. Isolation

of the specific defective component has been left to the technician.

NOTE

If the instrument’s performance does not meet specifications within 12 months of purchase date, contact your Keithley representative or the factory before attempting any troubleshooting or repair other than fuse replacement.

8.3.1 Line Power Fuse (FlOl) Replacement If power fails, first verify that the main fuse (FlOll is not

defective before disassembling the Model 192. (If the Line

Voltage Setting is changed (S102) the fuse must be re-

placed.) The fuse is accessible from the Model 192 rear panel. To replace. proceed as follows:

Test Equipment

Decade Resistor

1900.00 -t .5 digits

190.000 k .5 digits

19.0000 f .5 digits

1.90000 * .5 digits .190000 + .5 digits

.OOOOO * 2 digits

1.90000 * .5 digits

R381 - 1 .soooo R307

R353 R308

C412 R401 R410 R411 R409 C412 c411 C408

19.0000 -t .5 digits

190.000 * .5 digits

1000.00 f 2 digits

100.000 f 50 digits”

1000.00 * 4 digits

1.00000 f 4 digits

10.0000 c 4 digits

10.0000 * 4 digits

100.000 f 9 digits

1.00000 * 9 digits

Decade Resistor Decade Resistor

Decade Resistor Decade Resistor Decade Resistor

DC Calibrator (with Kelvin-

Varley Voltage Divider

DC Calibrator (with Kelvin-

Varley Voltage Divider)

DC Calibrator DC Calibrator DC Calibrator DC Calibrator DC Calibrator 745 AC Calibrator 745 AC CalibratoriAmplifie 745 AC Calibrator 745 AC Calibrator 745 AC Calibrator 745 AC Calibrator 745 AC Calibrator 745 AC Calibrator

8-2

LIN ADJ.

200k ---..

,nnnl, -

y* R307

R306

-a305 A304

303

Figure 8-1. Adjustment Locations

8-3

1. Turn power off by depressing the Model 192 POWER button, and disconnect the line cord.

2. The fuse carrier is spring loaded. Using a slotted screwdriver, push the fuse carrier in and rotate % turn

counterclockwise. The carrier and fuse will eject from the holder.

3. Remove the fuse from the carrier and replace par Table

8.3.

CAUTION

Do not install fuse with higher rating then specified. Instrument damage may occur.

4. To install the fuse and carrier into the holder, reverse the procedure in step 2.

Table 8-3. Fuse Replacement

Line

Voltage FlOl

90-125V 1/4A, 25OV, 3AG. SLO BLO

210-250V 1/8A, 25OV. 3AG. SLO BLO

Fuse

Keithley Part No.

FU-17 FU-20

8.3.2 Line Voltage Selection

Set up the Model 192 to operate on the available AC line

voltage 8s follows:

WARNING

Turn off power and disconnect the line cord before removing the case cover.

1. Remove the top covar.

2. Refer to Table 8-4 and sat switch 5102 accordingly.

3. install proper fuse per paragraph 8.3.1. NOTE

The line voltage setting of the instrument is

marked on the rear panel. The following procedure can be used either to confirm the factory setting, or to set up the instrument for

operating on another voltage range, If the

line voltage range is changed, the box next

to the selected line voltage should be appro-

priately marked as an external reminder of

the setting. Use a water soluble marking

pen.

Table 8-4. Line Voltage Selection

Input Line

Switch

Voltage Frequency SlM

105V-125V 50.400Hz 115v

21OV-250V 50-400Hz 230V

‘SOV-1lOV 50.400Hz 115v

‘195V-235v 50-400Hz 230v

‘Requires special factory installed transformer.

8.3.3 Disassembly If it is necessary to remove or replace a component, use the

followinq disassemblv procedure.

Remove the top cover as follows:

WARNING

Turn off power and disconnect the line

cord before removing the case cover.

A. Remove the two retaining screws located at the rear of

the instrument.

B. Grasping the top cover at the rear, carefully lift it off

the instrument.

C. When installing the top cover, make sure that the

three tabs located at the front of the cover engage in the front panel assembly.

Remove the top shield from the Analog board by firmly

lifting it off the four retaining slips. Refer to Figure S-l. When replacing the top shield, do not pinch any wires in the retaining clips.

If the AC option is installed, disconnect the brown and blue wires IP1014 and P1016) at the AC input and procede as follows:

A. Unplug the option from the analog board (PC-560). B. Detach shields from PC Board by removing the two re-

taining screws.

C. Refrain from any unnecessary touching of circuit com-

ponents; handle the board by its edges.

4. Remove the Analog board as follows:

A. Disconnect the input wires (white, green, gray. black

and red1 from the analog board fPC56OJ.

B. Remove the four screws retaining the analog board.

Lift the analog board up end place it on the side of the Model 192.

NOTE

A fifth screw may be located at the rear of the analog board. This screw must also be removed to saparate the analog board from the chassis.

5. If the Model 1923 IEEE option is installed, proceed as follows:

A. Unplug the Model 1923 ribbon cable from the mother-

board (PC-5591.

B. Remove the two screws holding the rear panel to the

chassis.

C. Remove the two screws that hold the rear panel to

the chassis (located under the Model 19231.

D. Lift the rear panel slightly and gently tap downward

on the chassis until the rear panel is dislodged from the chassis. The Model 1923 will still be attached to the rear panel.

E. Carefully remove the display board (PC-5301 ribbon

cable from the display board.

F. Remove the mother board from the chassis by pulling

the mother board toward the rear fawav from the front

8-l

panel) being careful not to damage the power ON switch. For reassembly, perform steps A through G in reverse

order.

NOTE

Recalibration of the Model 1910 AC Voltage Option may be necessary if any of the following occurs:

1. Removal/replacement of the 1910.

2. Disturbing position of the 1910 in the con-

nector.

3. Removallreplacement of shields on the

1910.

Refer to paragraph 6.5.3 to check AC voltage accuracy. lf calibration is necessary perform steps 12 through 19 in Table

6-Z.

6.3.4 Special Handling of Static Sensitive Devices CMOS devices are designed to function at very high impe-

dence levels for low power consumption. For this reason, a normal static charge build up on your person or clothing can be sufficient to destroy these devices. Table 6-5 lists the static sensitive devices in the Model 192 and the following steps provide instruction on how to avoid damaging them when they must be removed/replaced.

1. The integrated circuits listed in Table 6-5 should be handled and transported only in protected containers.

Typically they will be received in static protected containers of plastic or foam. Keep the devices in their

original containers until ready for use.

2. Remove the devices from their protective containers only at a properly grounded work bench or table, and only after grounding yourself by using a wrist strap.

3. Handle the devices only by the body. Do not touch the pins.

4. Any printed circuit board into which a device is to be inserted must also be grounded to the bench or table.

5. Use only anti-static type solder suckers.

Table B-5. Static Sensitive Devices

:hematic

Designation

u103. u104

U106

U123, U124

U125 U126 u129 u130

u131 U132 U322

a304, a307 0329-0332

Q335Xl336

Keithlay

Pert Number

IC-261 IC-135 LSI-15 IC-197 IC-250

PRO-113-E5

PRO-105, E5

LSI-27 LSI-26

IC-166 TG-139 TG-139 TG-139

6. Use only grounded tip soldering iron.

7. After soldering the device into the board, or properly inserting it into the mating receptacle, the device is adequately protected and normal handling can be resumed.

8.4 TROUBLESHOOTING PROCEDURE

This section contains tables listing step-by-step checks of the major DMM circuits described in Section 7. Theow of Operation. The following paragraphs provide instructions for using these tables. Read this information carefully before troubleshooting.

The Model 192 has a unique self-test feature upon power up. This feature enables the operator or technician to make a better judgement in isolating the problem to the Analog or

Digital portion of the DMM. Upon power up. all segments

will be displayed momentarily es follows:

[:ssasss]

Immediately following, the operator will note on the display:

Where F60 is the line frequency (basic integration period1

F60 = 6OHz F50 = 50Hz

C4 = Software Revision Level. (This number may differ

with different instrumentsI

When this initial indication is satisfactory. it is reasonable to assume the display and the microcomputer PROM memoi?’

are operating properly. This test enables the technician to isolate the problem within the Analog section of the Model

192. All ranges and functions can be tested via Program 8. When a specific range and function is selected, the program will step the Model 192 through a four sequence test which

is the same step sequence the Model 192 uses to make a measurementThe maior advantage of this program is that it

allows the technician to control the stepping sequence in

order to locate the problem. It also tests the display RAM and ROM circuitry.

To use Program 6. perform the following steps:

1. Press PRGM. The instrument will prompt for a program

number as follows:

j Pro IJ

The question mark will flesh.

2. Prea 6. The instrument will display the program number for K second es follows:

[Pro El

3. After the program number, the instrument will perform a display, RAM, and ROM test for a few seconds. A proper-

ly operating display will appear as follows:

~maaf388:

6-5

All front panel LED6 will also turn on.

4. If the RAM and ROM pass their respective tests, the instrument will briefly display the following message:

If the RAM teat fails. the followina rnessaqe will be

displayed:

If the ROM test fails, the instrument will disolav the follow-

ing:

rOE

5. Regardless of the outcome of the preceding tests, the instrument till continue with Program 8 operation and

prompt for a test number with the following message:

The question mark will flesh.

6. A test number, l-7. may be entered et this point by pressing the appropriate button. These tests are summarized in Table 8-6; note that tests 1 through 4 correspond to the N modes listed in Table 8-7 of the manual.

7. If en invalid test number is entered (-, 0, 6,9, ENTI, the instrument will respond with the following message:

r-iax--

8. Program 8 may be aborted at any time by pressing PRGM. To return the instrument to normal operation. press 0 after

pressing the PRGM button.

Table 87 indicates which particular component (FETI is ON for a selected function and range as the program steps through the four perts of the test IN4 through Nl, in

descending order). The Model 192 will step to the next sequence of the test when any front panel switch is depressed. For example: After the microcomputer has been cleared. the ZVDC function and range have been selected, and test PROGRAM 8 has been entered; pressing a front panel button will hold the Model 192 in the N4 mode of the

test. Refer to Table 8-7 and note that when the instrument is set at ZVDC and the N4 is entered, the gain of the Input Buffer (Amplifier1 is 10. In addition, Cl341 is the selected multiplexer FET that is switched ON. Scanning along N4 in that table, reveels that Q317 (Gain FET) end Cl322 (Transconductance FET) are also ON.

This technique greatly simplifies the task of troublashooting. Press another front panel button to step the

Model 192 to the N3 mode. Notice that the multiplexer FET selected now is Q327.

8.4.1 Line Power In general, start troubleshooting with Table8-8 to verify that

the power supplies are providing the correct voltages to the electronic components.

8.4.2 A/D Converter and Display Verify proper operation of the AID converter and display

before troubleshooting the signal conditioning circuits. Check the A/D converter and display Tables 8-9 and 8-10 respectively.

8.4.3 AC Converter

Problems with AC voltage may involve the Model 1910 AC Voltage Option. Check this circuit per Table 8-11.

8.4.4 DC Attentuator. Ohms Source and Resistor Problems with DC voltage or resistance ranges may involve

these signal conditioning circuits. Check these circuits per Tables 8-12 and 8-13.

NOTE

Dust, flux, or other contamination will degrade performance on resistance and DC

voltage ranges.

8.4.6 Digital Circuitry

Problems may exist with the microprocessor or associated circuitry. Check per Table 8-14.

All measurements are referenced to analog common IINPUT LO terminall. unless otherwise noted in the tables.

WARNING

Some procedures in the following tables

require the use of high voltage. Take cam to prevent contact with live circuits which could cause electric shock resulting in injury or death. The mother board shield is at INPUT LO potential. An input voltage floating high enough will create a shock hazard between the shield and earth ground.

8-6

Test Number

Table S-S. Teat Number Summarization

Test Function Displayed Message

Nmodes1-4 None See Table 87 of manual.

ROM Test

RAM Test Passes RAM test.

Display Test

r-mcc-

M L_rRL_I

1-l Will also turn on LED%

Comments

Passed ROM test.

Failed ROM test.

Failed RAM test.

N2 N3 N4

2ov

2V Nl

0.2v Nl

20Mn Nl

2Mn

200kn Nl

Nl N2 N3 N4

N2 N3 N4

N2 N3

Table 8-7. Program 8 A/D Test--ET Switching Sequence

ACV

cl311

a311

cm2 Q327 a341

Q312 0327 cl341

cl311

a312 Q327 a341

a312 Q327

a317

1 a319 cl322 a317

I 0317

a317 Q322. (1323

I a319

a319

03.19 I Q323

1 I

Q317

1 I

Input Buffer

Gain

Xl x10 x10

x10 x10 x10 x10

Xl x10 x10

x10 x10 x10 x10

x10 x10

Xl Xl

Xl Xl Xl Xl

Xl Xl Xl

Xl Xl

i: Xl

Xl Xl Xl Xl

x10

Multiplexer

FET ON

DCV

Q328 a341 a312

Q327 Q327

a341 cl341 0328

Q341

Cl327

Q341 0328 a311

0341 0327 cl341

D328

a341 CL327

a341 Q328 cl311

a341 Q327 a341 a341

a334 a339 a333 cl310

a334 a339 a333

0310

a334 a339 a333

a310 a334

a339 a333

a310

a334

a339

cl333

a310

a334

Q339

a333

a310

R Range

FET ON

a322

1 1

a305

ml. a305

0302. a305

(1323 (1306. Q3071

1 1

D323

cl303, a304

(1306. Cl309

6-7

step 1 A102 line switch

2 3 4 5

6 7 + 5V Digital

8 Emitter of 0104 9 + 15V Analog

10 Ulll Input 11 -15v 12 u112 Input 13 + 3ov 14 u113 Input 15 -30v

16 u114 Input

Item/Component

FlOl line fuse PlOll line cord

+ 5V Analog

U127 Input

On optional line voltage t

Table 8-8. Line Power Checks

Required Condition Must be set to 115V or 230V

as appropriate.*

Continuity Plugged into live receptacle

Turn on power

+5v, *5%

+7.4V minimum +5v, *5%

+ 6V minimum

+15v *lo96

+ 17.9V minimum

-15v. flO%

- 17.9V minimum +3ov, * 10% + 36V minimum

-3ov. flO%

- 36V minimum

Jnit

8 set to 115v.

Table 8-9. AID Converter Checks

Remarks

see paragraph 8.3.2

see paragraph 8.3.1

P1009 pins 9 Et 10, U127 output

Output of CR103 JlOlO, pins 1,2 (IEEE con

nector) Unregulated Input

P1009, pin 3, Ulll outpu

CR102 output P1009-1, u112 OUtpUt CR102 output P1009-2. u113 OUtpUt output Of CR101 P1009-4, u114 OUtpUt Output of CR101

step 1 Item/Component

2 Display

4 5 6 7 8 9

12 13 External voltage

14 15

U312 pin 12

R326 U308 pin 2 U316 pin 2 C308 lin) C308 lout)

External voltage source

Display

source

Display External voltage source

Display

Required Condition

Turn on power. Select 1000VDC.

000.00 +2 Digits 0 to + 4v square wave at

480kHz 20V for 16.6ms. OV for 1OOms

-2.5V. *7% (175mV) +5V, *7% (350mV)

OV, *15mV

See waveform per Figure 7-14 Select 2VDC range

Apply + 1.9OOOOV

1.90000 * 10 digits

Select 200mVDC range

Apply .OOOOOOV

Depress ZERO

00.000 * 1 digit Apply + 190mV

190.000 f 10 digits

Remarks Some tests here could fail due

to Digital board problems and vice versa.

480kHz clock Input Suffer output Transconductance Amp Bias Charge Dispenser bias Integrator input Integrator OUtpUt

Calibrated point

If different, check 2V reference Q327 kmrce)

Calibrated point

Input offset nulled Calibration point

If different, check 0.2V reference or X10 gain of Input Buffer.

8-8

Table S-10. Display Checks

Step 1 Item/Component

I1 I

3 U203 pin 1 4 U203 pin 8 5 U202 pins 4 and 5

S ;

3 4

+ 5V Digital U203 pins 2,9,14 or J1008. pin 14

tern/Component

1 I

lisplay

(

X311 source

X312 source

External voltage

source

Display ,

311 source I

IX312 scwce

External voltage

source

Display

m&r~*d voltage

Table S-11. AC Converter Checks (Model 1910)

) Required Condition Remarks

Turn on power. Select 1OOOVDC

range.

+5v *5%

Negative-going pulse I+ 5V to OV) occurring every 4OOqaac. 12.5kHz).

Required Condition

Turn on power and select 2VDC range.

Short input

.00020 * 10 digits 1omv

Same as step 4. plus reading at step 3.

Apply l.OOOOOV rms at 1kHz

1 .OOOOO + 100 digits

- 1V. plus reading at step 4 Same as step 5 Select 20VAC range

Apply lO.OOOOV rms at 1kHz

10.0000 -t 100 digits

Select 200VAC range and apply

lOO.OOOV rms.

Initial power up test checks all digits.

If low, check per Table 8-6.

Update data Clock input

Remarks Full scale input on all

ranges should produce approximately - ZVDC at output. P1014 (brown wire) on the Analog Board Do not perform unless AID test are completed.

Normal zero offset range. Impedance mater to

measure I > 1oSnl. Output

resistance is 300kR.

ACV Auto zero.

Calibration point,

DC outp”t Auto zero If any of above checks

fail, proceed to bias checks step 18.

Calibration point

I4 I5 I6

I7 18”

External voltage source

Display

100.000 + 100 digits

Select 1OOOVAC range Apply lOOO.OOV rms

1000.00 + 100 digits

TURN OFF POWER. Remove Modal 1910 AC Voltage Option from Model 192. Remove shields and reinstall the 1910 in the 192.

Select 2VAC range and short Input. Turn on power.

Calibration point

With shields removed,

display will be noisy and read many millivolts of AC pickup. Display will also change with operator mo”eme”t.

8-9

Table 8-11. AC Converter Checks (Model 1910) (Cont.1

Step Item/Component

20 R405, CR401 21 22 23 24

U401 Pin 2

R402,R406 Cl404, base Q403, emitter (1401, base

‘On Analog Board * Model 1910 must be recalibrated if step 18 was performed.

ItemlComponent

External voltage Display

External voltage

source

Display

External voltage

source

Display

Required Condition ov * 1OmV

OV *lOmV OV *lOmV

-7.5v * 10% + 5.7v * 10%

-3.6V *lo%

Table 9-12. DC Attentuator Checks

Required Condition

Turn on power. Select 200VDC range.

Apply + 19O.OOOV 19OJO * 10 digits Select 20VOC range Apply + 19.OOOOV

19.0000 f 10 digits Select 1OOOVDC range Apply + lOOO.OOV

1000.00 i 5 digits

Remarks

Summing junction, AC amplifier

DC oputput before filter Feedback circuit Base voltage 5 milliamp current source Bias for C404 protection

circuit.

Remarks

These checks should not be made if a problem exists on the 200mVDC or 2VDC ranges.

Calibration point 100~1 Attenuator

Calibration point

10: 1 Attenuator

Calibration point

1OOO:l Attenuator

8-10

Table S-13. Ohms Source and Resistors Checks

Step 1

10 11 12 13

14 15 16

20 21

23 24

Item/Component

Display

WlO. source 0344, collector

0310, sourca Q344. collector 1 .OOOOOkR

Display Q310. source INPUT HI

lO.OOOOkR

Display

lOO.OOOkQ resistor

Display

1 .OOOOM R resistor

Display

lO.OOOMO resistor

Display

Required Condition

Select 200 range and short

input with 18 guage (or lower)

copper wire (tin plated okay).

Less than 00.010

-0.4v *9%

-0.4v i7%

Select 2kR range

.OOOOO i2 digits

-4v *7%

Apply to input W-wire

connection)

1.00000 * 10 digits

-4v *7%

-2V +7% (half of step 11)

Apply to Input and select 20kO range

10.0000 f 10 digits Repeat Steps 11 and 12 Apply to Input and select

200kn range.

100.000 it 10 digits Repeat Steps 11 and 12

Apply to Input and select 2000kR range.

1 .OOOOO f 30 digits Repeat Step 18

Apply to Input and select 20MR range.

10.0000 * 100 digits Repeat Step 18

Remarks 30 not perform unless AID

:onverter and DC attenuator tests are completed. Two wire offset, including thermals

3hms reference voltage 3hms reference divider

3hms reference voltage 3hms reference divider Calibrated resistance

Range resistors Ohms reference voltage Voltage across unknown Calibrated resistance

Range resistors

Calibrated resistance

Range resistors Use meter with high input

impedance ( ) 1OW Calibrated resistance

Range resistors Use meter with high input impedance ( > 1OW. Calibrated resistance

Range resistors

Item/Component

U131 pin 39 U131 pin 37 U122 pin 9 UlOl pin 5 U106 pin 13 U131 pin 40 P1008 pin 15

P1008 pin 16

Table B-14. Digital Circuitry Checks

Required Condition Turn on power. Select 1OOOVAC I

range*

0 to c4V square wave et 4MHz 0 to +4V square weve at 1MHz 0 to +4V square wave et 1MHz 0 to +4V square wave at 480kHz 0 to +4V square wsve at 2.4kHz :

c5v *5%

Negative going pulse ( + 5V to OVI occurring every 833eec

Negative going pulse ( + 5V to OVI occurring every 100eec

Remarks Some tests here could fa

because of AID Convert1 problems end vice verse.

4MHz clock 1MHz clock 1 MHz 480kHz clock

2.4kHz clock Reset line Latch enable for Display

Board IPB51 Clock input for Display

Board (CA2)

8-1118-12

SECTION 9

REPLACEABLE PARTS

9.1 lNTROOUCTlON This section contains replacement parts information,

schematic diagams and component location drawings for the Model 192. Panel and Covers are shown separately in

Figure 9-1.

9.2 PARTS LIST Parts are listed alphabetically in order of their circuit

designation. See Table 9-1.

9.3 ORDERING INFORMATION

To place an order or to obtain information concerning

replacement parts, contact your Keithley representative or the factory. When ordering, include the following information:

Table 9-1. Model 192 Drawing Package

DESCRIPTION AC Converter

Mother Board (Digital and Power Supplies)

Analog Board

Display Soard

SCHEMATIC COMPONENT LAYOUT

29960D 29955c

30975D

1 30976D 1 308310 1 309740 308230

1. Instrument Model Number

2. Instrument Serial Number

3. Part Description

4. Circuit Designation (if applicable)

5. Keithley Part Number

9.4 FACTORY SERVICE If the instrument is to be returned to the factory for service,

complete the service form which follows this section and return it with the instrument.

9.5 SCHEMATIC DIAGRAMS AND COMPONENT

LOCATION DRAWINGS

Schematic diagrams and component location drawings

follow the replaceable parts list information contained in this section. See Table 9-l.

ASSEMBLY PC-496

30824D

PC-559

1 PC-560

PC-530

9-l

9-2

Figure 9-1. Exploded View With Mechanical Parts

Table 92. AC Converter PC496. Pana List

Circuit

Deslg.

c401 C402 c403 c404 c405 C408 GUI7 c409 c409 c410 c411 C412 C413 c414 C415 C418 CR401 CR402 CR403 CR404 CR405 CR408 CR407 CR408 J1008 J1007 JlOOB 0401 cl402 a403 (1404 Q405 R401 R402

R403 R404 R405 R408 R407 R409 R409 R410 R411

R412 R413 R414

R415

R418

R417

R419

u401

Description

.5&F, 5OV. Metallized Polycarbanate 1OpF. ZOV, Aluminum Electrolytic

3.3rF. ZOV, Aluminum Electrolytic BBOpF. 3V. Tantalum’

.22uF. 50V. Matallired P&carbonate BB2OpF, 83V. Polystyrene 41BpF. 5OOVDC. Mica Adjustable Capacitor, .819pF 3OpF. 5OOV. Mica

l&F. SOVDC. Tubular Ceramic

.2<1 &F, 200OV. Trimmer

.25-1.5pF. ZOOOV, Trimmer

lpF, IBVDC, Ceramic Disc 1OpF. ZOV, Aluminum Electrolytic .05#F. 1OMPJ. Ceramic Disc 1OpF. 1OOOV. Ceramic Disc Diode. Diffused. Silicon, lN914 Diode, Diffused, Silicon, lN914 Diode, Diffused, Silicon, lN914 Diode. Diffused, Silicon, lN914 Diode, Diffud, Silicon, lN914 Diode. Diffused. Silicon. lN914 Diode. Diffused. Silicon, lN914 Diode. Diffused. Silicon, lN914 Connector. Female. 12 Contacts Lug. Receptacle Lug, Receptacle

Transistor, NPN, Silicon, 2N5099 Transistor. PNP. Silicon. 2N5087 Transistor. PNP: Silicon, 2N6097

Transistor, NPN, Silicon, 2N3904 Transistor, PNP. Silicon, 2N3906 Pot, son. 10%. %W

249G. .l%. l/lOW, Wire Wound ZlSlKJ, .l%, l/lOW, Wire Wound

150kfl. 5%. XW, Carbon or Composition 150kfl. 5%. ‘/W, Carbon or Composition 1Okil. 5%. %W. Carbon or Composition

284.2tI. 5%. Part of a Matched Set 24Ofl. 5%. % W. Carbon or Composition

Pot. loon. 10%. %W Pot, 1OkQ 10%. %W Pot, IktI. 10%. +‘.W

4.75k. .5%. Part of a Matched Set

54.7k. .5%, Film Thick Film, 5%. Resistor Network 495k. .5%, Part of Matched Set

33klI. 5%. %W. Composition 47kG. 5%. %W, Composition ZMSI, .5%, Part of Matched Set Monolothic J-FET OP AMP, LF356

LocatIon

ich. Pcb.

F3 5102 F4

8103

7103 9183 S/82

lo/B2

ll/C2 12/u

05 04

13lCZ 14102

15lD2

18/U

17103

lBlD3

19/E2

24183

25/B3

26183

27183

29183

29/B3

30lD2

31/u

34lC3

35/Fl

3wA3

45lA2

48/02

47183

4B/B3

49fC2

52102

53/ 82

54182

55182

58182

57183

59i 82

59183

60182

81/B2

62/C2

83/BZ

64182

65/C2

86/C2

61102

68/u 69/U

72lD2

Par? Nd.

C-201-.56 c-314-10 C-321-3.3

C-297-690 c-201-22

c-29SBB2op C-278419~ C-225 C-2353Op

c-292-1.50

C-216

C-216 C-236-. 1 c-314-10 C-298-.05 c-84.lop RF-29 RF-29

RF-29 RF-28 RF-25 RF-29 RF-29

RF-29

CS-337.12 LU-90

LU-90 TG-62 TG-81 TG-61 TG-47 TG-84

RP-99-50

R-241-249

R-241-2191

R-76150k

R-7615Ok

R-76.10k

R-266

R-76240

RP-99-100

RP-BS-10k

RP-9Slk

R-288

R-27554.7k

TF-72

R-266

A-7633k

R-7547k

R-266

IC-152

Manufacturers Designation includes Pan Description: e.g.. CR 25, 22, 5%

**Manufacturers Designation is GP %. 1%. TlOO, Resistance Value.

Table 9.3. Mother Board PC-569, Parts List

CIrdt Deaig.

AT-101 AT-102 AT-103 AT-104 c-104 c-105 C-106 c-107 C-108 c-109 c-110 c-111 c-112 c-113 C-l 14 c-115 C-l 16 c-117 C-118 c-119 c-120 c-121 c-122 C-123 C-126 C-126 c-129 C-132 c-134 c-135 c-137 C-138 c-139 c-140 c-141 C-142 c-143 c-144 c-145 c-146 c-147 CR-101 CR-102 CR-103 CR-104 CR-105 CR-106

F-101

F-101 J-1006 J-1009 J-1010 J-1011 L-101 a-101 cl-102 a-103 Q-104 R-101 R-102

Description

Optical Isolator, 6N137

Optical Isolator, 6N137 Optical Isolator, 6N137 Optical Isolator, 6N137

.lpF, 16V, Ceramic Disc

.lpF, 16V. Ceramic Disc

.1&F, 16V. Ceramic Disc

.lpF, 16V. Ceramic Disc 66pF. 1OOOV. Ceramic Disc 47pF. 1OOOV. Ceramic Disc

.lpF. 16V. Ceramic Disc

.lpF, 16V. Ceramic Disc .lpF, 5OV. Ceramic Disc lOpF, 25V. Aluminum Electrolvtic

lOpF, 25V, Aluminum Electrolytic 1OrF. 35V, Aluminum Electrolytic 1OpF. 35V. Aluminum Elect&tic

479F. 35V. Aluminum Electrolytic

47O@F, 35V. Aluminum Electrolytic 47OpF. SOV. Aluminum Electrolytic 47OrF. 5OV. Aluminum Electrolytic 22OOpF. 25V. Aluminum Electrolytic

lO$F, 25V. Aluminum Electrolytic

.lpF, 5OV. Ceramic Film 6EOOpF. 5OOV. Ceramic Film 22pF. 1OOOV. Ceramic Film 22pF. 1OOOV. Ceramic Film O.lpF, 5OV, Ceramic Film

11.6OOpF. 25V, Aluminum Electrolytic 22OOpF. 5OOV. Ceramic Disc 47OpF. 2OOOV. Ceramic Disc 47OpF. 2OOOV. Ceramic Disc

.lpF. 5OV. Ceramic Film .l@F. 5OV. Ceramic Film

4.7~F, 2OV. Tantalum

.lpF. 5OV. Ceramic Film .lpF, 5OV. Ceramic Film .lpF, 5OV. Ceramic Film .lpF, 5OV. Ceramic Film .luF. 5OV. Ceramic Film l~F,‘SOV,‘C&mic Film RECTIFIER BRIDGE 11.5A). PF40 RECTIFIER BRIDGE l1.5A). PF40 RECTIFIER BRIDGE (5AI. .+EO5 RECTIFIER BRIDGE 15AI. PE05 Silicon Diode, lN914. Silicon Diode. lN4607 FUSE, % AMP (115VI FUSE, l/6 AMP (23OV) CONNECTOR CONNECTOR

CONNECTOR

Power connector 1OOpH

N-Channel, J-FET, 4392 NPN. Silicon, 2N3904 NPN, Silicon, 2N3904 High Gain Darlington, D45El 10k. 5%. ‘/rW. Composition lOk, 5%. XW, Composition

Location

Sch. Pcb.

l/E2 83 l/W

83 l/W l/El

l/G3

l/F2 l/F3 l/F5 l/F6 l/F6 l/E6 l/M l/F4

2lD3 2lD3 2lD3 2lD4 2/u 2/D3 2/u 2/D4 2lC2 2/D2

l/E6 l/E5 l/B3 1183

i.2

7/83 8183

S/B3 10/a 11/w 12lC3

13/D3

14103 15/B3 16/D2 17/D2 lSlD2 lS/D3

20/El

21/u 22lE2

23/W 24/W 26/4E 26165 29lC4 31ID4 32/M

35/D4 2/C5 2104

N/A

N/A l/B1 l/A3 1 IA6 l/B6 l/E6 l/C5 l/C6 l/E3

l/E6

2lC3 2/C3 2/u 2lC4

2lE5

2/05 2iA4 2lA4

l/H1 l/H1

2/A5

l/F6 l/F6 l/D6

2105 2104 l/G4 l/G1

37lE4 391F4 4OlE4 411F4

421C4

43/F5 44/c5 45185 46184

1711D3 172/D4 173/83

174/E5

49lF2

5O/F2

511F3

52/F4

53/E4

541 E4 62lG4 62/G4

72/2C. 21

73lF5 74lG4 63lC3 77lD3 78/E5 79lE4 801 F4 95/82 66/B2

Kalthley Part No.

IC-292 III-292 IC-292 IC-292

C-23&.1

C-238.1

c-238.1

C-238.. 1 C-64-6&l

C-64470 C-238.; c-238.1

C-237-.1

c-314-10

c-309-10

C-299-470 C-284470

c-292-470

C-292-470

c-290-2200

c-314-10

C-237. 1

c-zz-6socm

C-64-22p

c-6422ll

C-237..i

C-314-11600

c-22-22oop

C-324-4701,

C-324.470~

c-237-.1

C-237-.1

c-179-4.7

C-237.. 1

c-237-.1

C-237.. 1

c-237-.1

C-237-l .O

RF-46

RF-48

RF-29

RF-41

FU-17

FU-20 30575A

CS-369-2

cs-399.1 cs-366 CH-14 TG-77 TG-47 TG-47 TG-127 R-7610k R-7610k

Table S-3. Mother Board PC-669. Parts List ICont.1

:ircuit >esig.

q-103 t-104 7-105 7-106

7.107 q-109 q-109 7-l 10 S-1 11 7-112 7-115 7-116 7-117 7-120 7-121 q-122 7-123 q-124 q-125 q-126 q-127

3.129 R-129 R-130 R-131 R-132 R-133 s-101 s-102 T-101

u-101 u-102 u-103

u-104 u-105 U-106 u-107 U-106 u-109

u-110 u-111 u-112 u-113 u-114 u-120 u-121 u-122 U-123

U-124 U-125 U-126 U-127 u-129 u-129

u-130

u-131

U-132 u-133 Y-101 Y-102

Description

10k. 5%. %W, Composition

2200. 5%. %W, Composition 22Oil. 5%. ‘/W, Composition 22OQ 5%. % W, Composition

22011. 5%. %W, Composition

220.5%, NW, Composition IOMEG, 10%. %W, Composition

4.7k. 5%. %W, Composition

Thick Film Resistor Network

10k. 5%. %W. Composition lk, 5%. ‘/W, Composition

1.5k. 5%. %W, Composition 10k. 5%. ‘/W. Composition

4.7k. 5%, %W. Composition

47MI, 5%. %W, Composition 4700, 6%. %W, Composition 47M2, 5%. %W. Composition 47Ofl. 5%. ‘/W, Composition

1M. 5%. %W. Composition

5.36k. 1%. 1/6W. Film 2430, 1%. lI6W. Film

2.67k. 1%. l/SW, Film

12ln. 1%. 1/6W, Film

3.3k. 5%. %W. Composition

10k. 5%. ‘/rW, Composition Thick Film Resistor Network Switch, Power Switch K-l Transformer

Duel 4 Bit Counter, 74LS393 Quad. Z-Input Nand Gate, 74LSOO 9 Bit Shift Register. MCI4994

8 Bit Shift Register, MCI4094

ECD to Decimal Decoder. CD4028

Dual 4 Bit Counter. 74LS390

Quad 2-Input And Gate. 74LSO6

Dual “0” Flip-Flop, 74LS74 Ouad 2-Input Nand Gate. 7400 6 Bit Shift Register. MCI4094

+ 15V Regulator. 76M15

-15V Regulator, 79M15

Regulator, LM317

-24V Regulator, LM337

Ouad Exclusive OR Gate, 7496

Dual 2 to 4 Line Decoder, 74LS139

Quad 2-l,, Nand Gate. 74LSOO

1024 x 4 Bit Static Ram, 2114 1024x 4 Bit Static Ram, 2114 Oscillator/Clock. MC4060 Up/Down Counter. 74C193

+5v Regulator. 7905 Bus Driver, MC14503 K-l Programmed ROM K-l Programmed ROM Microprocessor. MC6606 Interface Adapter, SY6522 5V Regulator. 76605

3.84 MHZ Crystal

4.0 MHZ Crystal

Location

Sch. Pcb.

l/Cl 67102

l/52 l/E3 l/E4 l/F1 l/F5 l/F6 l/E6

l/E6 SEV

l/D5.E4

2/D5 2lD4

l/E6

l/D6

l/F2 l/F3 l/F4 l/El

2/65

2lA4 2lA3

2/&C

2.3.4 l/G2

Fl.G2

l/H3

l/F5 l/H4 l/G6

IAZ.A3.F2.F5

1 /F3.G2

l/Fl.Gl.G2

l/G4

z/o2 2/D3 2/ D3 2/ D4

l/El.E4

l/D3

l/D5,E5,W

l/D5

l/C6 l/E4 l/E4

Z/D2

l/D6 1165 l/65 l/B2 l/C2

2lD4

l/F6

l/B3 166104

68163 69/83 SO/E3 91/u 92/C3 93/u 94103 96/D3 96164

99/E4 lOO,E4 lOllE4 104lE5 105/E5 106163 107/63 106/93 lOS,C3

llOlE4

llllE4

163/U

164/E3

165/E3

166lE4 169104

170104

112lSl 113/Gl

116,117

F2 119/62 120/62

12l/C2 122lC2 123/02 124163

125/83

126/C3

127/C3

126/D3

129,El

130/u

131152

132/E3

139/64

139.c4 14OlC4 141104 142104

143lE4 144lE4 145/F3 146194 147/c4 14wc5

149/04

1501D5

151/F4

167/C3

Wthley brt No.

q-7BlOk

3.76-220 q-76220 q-76-220

3.76.220 q-76-22

9.7810M R-7647k 9-764.7k TF-99 R-78101: R-7611; R-7615k A-7810k R-764.7k R-76-470 R-76470 R-76470 R-76470 R-761?.’ R-685.36k R-66-243 R-BB2.67k R-68-121 R-763.3k R-7610k TF-101 SW-426 SW-397 TR-160 TR-199

IC-213 X-163

K-251 IC-251 IC-135 IC-212 IC-215

IC-144

IC-36

K-251

IC-194

IC-195 IC-306 IC-309 K-116 IC-182 K-163

LSI-15 LSI-15 IC-197 IC.310 IC-93 IC-250 PRO-113.E5 PRO-lOSE5 LSi-27

LSI-26 IC-223 CR-13

:R-10

s-6

Table 94. Analog Board PC-560, Parts List

Circuit

Dssig.

Z-301

Z-302

z-303

z-304

z-305

z-307

3-306

z-310

C-31 1

C-312

c-313

C-314

z-315

CR-301

CR-302

CR-305

CR-306

K-301

P-1009

P-1012

P-1014

a-301

O-302

n-303

n-304 cl-305 O-306 n-307 n-309 a-309 Q-310 Q-31 1 Q-312 o-313 Q-314 cl-315 Q-316 a-317 Q-316 a-319 Q-321 D-322 Q-323 Q-325 G-327 Q-326 G-329 Q-330 a-331 Q-332 G-333 a-334 Q-335 Q-336 Q-337 cl-336 a-339 a-340

Description

6SpF 5% 5CW Polystyrene 33OpF 5% 5OOV Polystyrene 68OOpF 20% 5OOV Ceramic Disc 6BOOpF 20% 5OOV Ceramic Disc

1OOOpF 5% 5OOV Polystyrene 15OpF 10% 1OOV Ceramic Disc

36OOpF 5% 5OOV Polystyrene

1OOOpF 5OOV Polystyrene .lpF 16V Ceramic Disc 1OOOpF 5OOV Polystyrene .lpF 16V Ceramic Disc

1.5pF. 5OV. Tubular Ceramic .lpF. 5OV, Ceramic Film Diode Current Unit, J505 Diode Current Unit, J505 Diode. lN914 Diode, lN914 Relay 2PDT Cable Assembly

connector Connector N-Channel FET N-Channel FET N-Channel FET N-Channel FET, PF5301 N-Channel FET, 2N4392

N-Channel FET N-Channel FET, PF5301 N-Channel FET N-Channel FET. PF5301 N-Channel J-FET N-Channel J-FET N-Channel J-FET Selected low leakage Transistors NPN Silicon. 2N5551 PNP Silicon, 2N4355 NPN Silicon, 2N5551 N-Channel J-FET N-Channel J-FET N-Channel J-FET N-Channel FET. 2N4392 N-Channel FET, 2N4392 N-Channel FET. 2N5432 N-Channel FET. 2N4392 N-Channel J-FET N-Channel J-FET N-Channel J-FET PF5301 N-Channel J-FET PF5301 N-Channel J-FET PF5301 N-Channel J-FET PF5301 N-Channel J-FET N-Channel J-FET N-Channel J-FET PF5301 N-Channel J-FET, PF5301 N-Channel J-FET. PF5301 N-Channel J-FET. PF5301 N-Channel J-FET’ Selected Device

Location

Sch. 2/81

2lC2 2lC5 2lC5 l/D1

Pcb.

7lC2 WC2

l/c3

2lC3

ll/C4

ZIG5 13lD4

Z/F2 14lF4

l/D2 16/C4 l/W l/A3 l/D6

2104 2/85

l/D1

2lG5

l/D1

17/F5 w/04 lSlF5

24lD3 25/ D3 2SlC4 2WD4

lSO/C4

A5.61

E4,E5

l/B2 l/D2 1164 1184 l/C4 l/C4 l/E4 l/B4 l/C4 l/D4 l/D4 l/W

l/F2

l/F2 l/D4 2164 2185 2/ 83 2102 2184 2102 21 El 2/ D2 Z/D1 2lG6

l/F2 l/D1 l/D1

2lA2 2/Al

l/G2 l/G2

l/E3

l/E3 l/D3

36/D, 37lD5

39lC4 43/83 44163

45/63 46/62

47/c3

a/c2

49/c2

5OlC2

51 /c2

52/c3

WC3

54lC3

55/c3

55/ 03

57lD3

56lD3

58, D3

60/ D3

61 /D3

63/E3 64/ F2 65lF2 67lE4

7o/c4

71lC4

72lC4

73lC4

74/c4

75/c3

76/C4

77/c4

7S/B3

79/83

l/D3 BOlE4 l/G2 El/C4 l/D3

62/C4

Ksithlsy

Pan No. C-136.68p

c-136.33op C-22.6800~

C-22.6600~

c-13S-looop C-64.150~ C-136-36000 C-136-1000~ C-236-.1 c-136-10000 C-236-.1 C-282-l&F

C-237-.1 TG-140 TG-140

RF-26

RF-29

RL-51

CA-12-2 29995A

cs-357 31841A 31641A 31841A

TG-139

TG-129

31641A

TG-139

31841A

TG-139

30966A

26234A

TG-67

TG-90

TG-67

30966A

309tEA

30966A

TG-126

TG-128

TG-151

TG-128

30966A

TG-139

30966A

TG-139

30966A

26234A

(

Circuit

Deslg.

a-341

a-342

(

n-343

n-344 I

n-345 ,

D-346

3-347

s-346

3-349

a-350 I

R-301 I

R-302 I

R-303 I

R-304 I

R-306

R-306 I

R-307 I

R-308 I

R-309 I

R-310

R-311 R-312

R-313

R-314

R-315

R-316

R-317

R-318

R-319 R-320

R-321

R-322

R-323

R-324 R-326

R-328 R-330 R-332

R-333

R-334 R-335 R-336 R-338 R-339 R-340 R-341 R-342 u-343 R-344 R-345 R-346 R-347 R-346

R-349 R-350 R-351

R-352 R-353

R-354

R-356

Table S-4. Analog Board PC-680. Parts List IC0nt.l

DeSCIlptlOIl

N-Channel J-FET NPN, MPS-US5 NPN Silicon, 2N5551 NPN HI Volt Silicon, TIP.49 Selected Device NPN Silicon, 2N3904 PNP Silicon, 2N3908 PNP Silicon, 2N3906 PNP Silicon 2N6067

PNP Silicon, 2N5067 50k Cermet Pot 54 Cermet Pot

6000 Cermet Pot 5OC Cermet Pot 200k Cermet Pot 20k Cermet Pot

1000 Cermet Pot

l.lOBM .l% %W Metal Film

140k 1% 1/8W Metal Film

1.005k .l% l/lOW Metal Film

100.7k .l% 1IlOW Metal Film

9.9& .l% l/low Metal Film

100.6 .l% l/low Metal Film

13.3k 1% 1/8W Metal Film

lk 1% YIW Composition

Matched 8et with R319

1OOk 1% %W Composition

Matched 881 with R317

1M. 5% %W Composition

1M. 5% %W Composition Thick Film Resistor Network

1OOk 1% %W Composition

50k .l% l/low Metal Film

Thick Film Resistor Network

1M 6% %W Composition

2OOk 1% Y.W Composition

1On 1% ‘/W Composition

1On 1% %W Composition

1M 6% %W Composition

300k 5% ‘hW Carbon

300k 5% %W Composition

Thick Film Resistor Network

1M 5% YIW Composition

1M 5% %W Composition

9.99M .l% Metal Film

300k 5% XW Composition

1M 5% %W Composition 300k 5% ‘/W Composition 300k 5% %W Composition 200k 1% l/8, Metal Film 1OOk 5% %W Composition Thick Film Resistor Network 2000 Cermet Pot

lhl 5% %W Composition

1M 5% %W Composition

l.OCOtlOn

Sch. Pcb.

l/F2

l/D1

l/F3

Z/G5

z/F5

21 F2 2/w ZIG2 2lD4 21D5

llA4

1104

1184

l/C4

l/W z/c2 z/c2

l/B3

l/C3

l/W

1183

l/B3

l/D3

l/D3 Z/El z/C3 Z/El z/c2 2/ 63 2/ t34

WC4 84104 65/D4 86/ D5

07lE4 88lF4 ES/F4 9O/E5 91/F5

92/F5 lOS/BZ 106/82 107/u 1owC2 lOS/CZ llO/C2 llllC2 llZ/CZ 113/82 114/82 1wc2 11wC2 117/C2 1wc2 119/u 120/u lZl/CZ 122/a 123lC2 124IDZ

125/D2

Dl-3.E2.3

21 D3 Z/D2

Z/D1

Z/El.F1-4

2/ 82 Z/83 2184 2185

l/G3

l/F3

l/F3 l/C5 l/W

lA4-6.l3.M

l/G3 l/G3 l/A4 l/D4 l/D3 l/G3 l/C3 l/D2 l/Al l/B2

l/A2.1-2

127/F2 126/F2 13O/FZ 132lF3 134/D3 136/D3 137/D3 138103 139/c3 140/a 142/C3 143/c4 144/C? 145/K 146/83 147183 148183 149184 150/84 151/84 152184 153/c4 154/c4 155/a 15wc5

l/B2 157185

l/F3 15wc4

l/F3 16O/C4

26/U

Part Nd. 30966A

TG-133 TG-67 TG-137 20234A TG-47 TG84 TG-84 TG-61 TG-61 RP-8950k RP-ES-5k RP-89500 RP-69.50 RP-89.20Ok RP-8920k RP-89.100 RP-89100 R-2641.108M R-86-140k R-263.1.005k Ii-263.100.7k R-263-9.9& R-263-100.5 R-86-13.3k R-76-11; R-292.LIk R-76100k R-292-72.& A-7BlM R-76-1M

TF-111

R-76100k R-7610Ok R-263.50k

TF-85

R-761M R-76200k R-7610 R-7610 R-761M R-751M R-761M R-282.300k R-282-300k TF-108 R-76lM R-761M R-2949.99M R-282.300k

R-282.300k

R-761M R-282.300k R-262.300k R-247.200k R-282.100k

TF-83

RP-69-200 R-761&l R-761M

Table S-4. Analog Board PC-660, Parta Lilt lCont.1

Circuit Deslg.

R-357 R-359 R-360 R-361 R-362 R-363 R-364 R-367 R-366 R-369 R-370 R-371 R-372 R-376 R-377 R-379 R-379 R-360 R-361 R-382 u-301 U-302 u-303 u-304 U-306 U-306 u-307 U-308 u-309 u-310 u-311 U-312 u-313

u-314

u-315

U-316 u-317

U-316

u-319

U-320

U-321 u-322 UR-301

UR-302 UR-303 v-301 V-302 v-303 v-304 v-305

Description

1M 5% %W Composition Thick Film Resistor Network 209k 1% YI W Composition Thick Film Resistor Network 220k 10% HW Composition

lOOk, 10%. 1W. Composition

1M 5% YW Composition

S&XXEd

S&Cted Thick Film Resistor Network 2OG cemlm PO1

Resistor sat 45.Sk

Resistor set 20k

2.67k 1% l/SW Metal Film

80.4k 1% l/SW Metal Film

40.2k 1% l/SW Metal Film

1OOk 2W 10% Composition

699 .l% l/low, Metal Film

1oOk Pot

3.3M 5% %W Composition

OP.AMP Selected

OP.AMP, LF356

OP-AMP, LM343

Clued Comparator, LM339

Cluad Comparator, LM339

atlad Comparmor, LM339 J-FET Input OP-AMP, LF351 J-FET Input OP-AMP, LF351 Comparator, LM311 Transistor Package, CA3086 Transistor Package, CA3066 Guad Z-In. NOR Gate, 74L502 J-FET Input OP-AMP, LF351

Dual “D” Flip-Flop, 74574 J-FET Input OP-AMP, LF351 J-FET Input OP-AMP. LF351 Voltage Reference Guad Comparator. LM339 Cud Comparator, LM339 J-FET Input OP.AMP, LF351 Cluad Comparator, LM339

BCD to Seven Seg Driver, 4511

6.3V Zener

6.3V zenet S.lV 2ener Jumper Jumper Jumper Jumper Jumper

Locmlon

Sch. Pcb. l/G3 161 IC4

SEV

l/F3

2164 ZIG4 ZIG6

l/C5 l/C5

l/C6 l/C5

l/C6 ZIG6 z/F6 z/F6

l/81

l/AZ

2/R 2/Q Z/Al 2lA6 Z/81

l/R SEV

2/Q

z/F3

I,Fl,F3

z/F2

32. HZ l/C5

2lD4

l/D6

Z/G6

l/Cl

Z/S4 2166

l/D1

z/C4 2lC5

l/C5 l/D5 l/D5

163/D4 164/D4 165/D4

1661E4 167lE4 16SIE4 171/E5 172IE5 173/E 174/E5 175lE5 176/E5

lSDlE4 181/W 162/W 163lC‘l 184105

lSSIF4

1961F3

192/C3 193ID3 194/C2 195/02 lSB/DZ

197/Q

196/Q

lSS/F3 ZOO/F3 20110 202/u 203lE4 2D4lF4 205/F4

206F4 207/F5 2OSlF5

20SlD3

2101D‘l 2111D4 212/D4 213/B

222164 223104 224lD4 229/D? 230lD3 2311D4 232/D4 233lD4

Kelthlsy Part No.

R-761&? TF-109 R-76200k TF-105 R-l-220k R-2-100k R-76-1M Selected Selected rF-110 RP-SS-20 R:29345,9k R-293-20k R882.67k R-8860.4k R-Slb40.2k R-5100k R-263-699 RP-97-100k R-763.3M 30167A IC-162 IC-254 IC-219 IC-219 IC-219 30154A 30154A IC-173 2919SA 2SlSSA IC-179 K-176 K-216 30154A 30154A

29996 IC-219 IC-215 30154A IC-219 IC-166 DZ-56 DZ-56 DZ-14 J-3 J-3 J-3 J-3 J-3

S-9

Table 9.5. Display Board PC-530. Parts List

Circuit De&.

c-210 DS-201 DS-202 DS-203 DS-204 DS-205 DS-206 DS-207 DS-206 DS-207 DS-210 DS-211 DS-212 DS-213 DS-214 DS-215 DS-216 DS-217 DS-219 DS-219 DS-220 DS-221 DS-222 a-201 a-202 a-203 a-204 o-205 a-205 a-207 a-209

R-201 R-202 S-201 s-202 S-203 S-204

S-205 s-205 S-207 s-205 s-209 s-210 s-21 1 s-212 S-213 u-201

u-202 U-203

Dascriptlon

lO#F, 2OV. Alum Elect ” f ” Digital Display “5” Digital Display “5” Digital Display “6” Digital Display “5” Digital Display “5” Digital Display “5” Digital Display

Pilot Light Pilot Light

Pilot Light

Pllot Light

Pilot Light

PNP SIL Transistor. 2N4355

PNP SIL Transistor, 2N4355

PNP SIL Transistor. 2N4355 PNP SIL Transistor, 2N4355 PNP SIL Transistor, 2N4355 PNP SIL Transistor, 2N4355

Thick Film Resistor Network

Thick Film Resistor Network Switch Switch Switch Switch Switch Switch

Swkch Switch Switch Switch Switch Switch Switch MDS to LED Segment Driver. 75492

MOS lo LED Segment Driver. 75492 Bit Shift Register, 74LS164

LocatIon

Sch. Pcb.

62 a/02

E D2 D2

Q Q Q Q

Q H3 H3 G3

z G3

F3 F3

G3 E

F4 F4

F4,G4,H4

F5.G5,H5

84 A4 A4

64 A4 A4

64 A3 A3

33, 4, C3. D3 14, D4. E4, F4

3/D3

9182 10102 lllC2 lZlC2 13/C? 14lC2 lS/DZ 15/02 17lD2 16163 19/83

20183 21/C3

22/w 23/D3 24/D3

25153

26183

27/W

20lC3 291 D3

33/D2

34/D2

35lD2

37/D2

39102

39/c3

4OlDZ

46/c2

47102

51/B3 52/63 53/83 54/u 55/u 56/ D3 57lD3

58163 59183 6O/C3 61/U 621D3 63lD3 67163 66/c3 6% U

Kslthley Psn No.

c-175-10 DD-31 DD-30 DO-30 DD-30 DD-30 DD-30 DD-30 PL-57 PL-67 PL-67 PL-67 PL-67 PL-57 PL-57 PL-67 PL-57

PL.67 PL-67 PL-57 PL-67 PL-67

PL.57 TG-60 TG-90 TG-50 TG-90 TG-90 TG-60

TG-90

TF-165-l

TF-77

SW-435

SW435

SW-435

SW-435 SW-435 SW435 SW-435 SW-435 SW-435 SW-435 SW435 IC-169

K-159 IC-127

5-s/5-10

9-1119-12

n i

”

1: 5

Figure 43. Mother Board. Component Location Draw-

ing. Dwg. No. 36624 isheet 2 of 21

%15/B-16

.- I N

I m

I n I

Figure 94. Analog Board. Component Location Draw-

ing. Dwg. No. 30831 lshwt 2 of 21

Figure 9-5. Display Board. Component Location Draw-

ing. Dwg. No. 30823

9-2119-22

Figure 9-b. AC Convsrcer. Shematic Diagram. Dwg.

No. 29960

92319-24

Figure 9.7. Mother Board. Schematic Diagram. Dwg.

No. 30975 (sheet

1 of 21

925/ 9-26

TIOI

‘5”

Figure 9-7. Mother Board. Schematic Diagram. Dwg.

No. 30975 (sheet 2 of 21

9-271920

w I

---- -_---.

ANGE RESlSTORS

Figure 9-8. Analog Board. Schematic Diagram. Dwg.

No. 30976 lshwt 1 of 21

9-2919-30

Figure 9%. Analog Board. Schematic Diagram. Dwg.

No. 30976 laheet 2 of 2)

9-n I932

a bL60E _

Figure 9-9. Display Board, Schematic Diagram, Dwg.

No. 30974

9-33/s-u

SERVICE FORM

Model No. Name Company Address City

List all control settings and describe problem.

Show a block diagram of your measurement system including all instruments connected (whether power is turned on or not). Also describe signal source.

Serial No.

state

P.O. No. Data

Phone

ZiP

(Attach additional sheets as necessary.)

Where is the measurement being performed? (factory, controlled laboratory, out-of-doors, etc.) What power line voltage is used?

Frequency?

Variation?

Any additional information. (If special modifications have been made by the user, please describe below.)

*Be sure to include your name and phone number on this service form.

OF. Rel. Humidity?

Ambient Temperature?

Variation?

OF.

Other?

Keithley 1910, 192 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual