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Model 195
Instruction Manual
Contains Operating and Servicing Information for the
Model 195 Digital Multimeter
Publication Date: August 1983
Document Number: 195-90%OIC
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from
date of shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batter-
ies, diskettes, and documentation.
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 representative, or contact Keithley headquarters in Cleveland, Ohio. You
will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility.
Repairs will he made and the product returned, transportation prepaid. Repaired or replaced 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 product modification without Keithley's express written consent, or misuse
of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leak-
age, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN
ARE BUYER'S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRU-
MENTS AND SOFTWARE EVEN IF KEITHLBY INSTRUMENTS. INC.. HAS BEEN ADVISED IN ADVANCE OF THE POS-
SIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES'sHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS
OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAM-
AGE TO PROPERTY.
Road - Cleveland, OH 44139 - 440-248-0400 -Fax: 440-24X-6168 * http://www.keithley.com
Instruction Manual
Model 195
Digital Multimater
01992, Keithley Instruments, Inc.
Cleveland, Ohio, U.S.A.
SPECIFICATIONS
2.4 $4 Oh+353 0.04+10 1 v
,I" `Ivldt@t mode,dividecounte"vr by 10.Above 0.5% Range.
RESPONSE:True mot mean square, AC coupled.
CREST FACTOR (ratio of peak to rms): Up to 3:l allowable.
OVERLOAD PROTECTION: 2A fure UOVI, externally acceaible.
MAXIMLIM ALLOWABLE INPUT: IWDV peak BENCH READING RATE: 3 read&/second.
BENCH READING RATE: 5 readbwlaecond. IEEE488 BUS IMPL!ZMENTATlON
MuMIne Cad: DCL, LLO, SIX. GET, GTL. LINT. UNL, SPE. SPD.
Unlllne Commands: IFC. REN. EOI. SRQ. ATN.
Interface Fwuttow: SHI, AHl. T5, TEO. L4, LEO, SRl. RLI, PPO, DCI,
DTI. co. El.
PTble Paramemr: Range. Function, Zero. integration Period, Ave+
EOI, T r. Terminator, Delay', loo-rdg. Storage, Calibration,
i%i$,, Multl~Off. Status, ServtceRequest. Self Test, Output Fannat.
`First reading is cotsct when step input is c~incldem with trigger.
2Mo 10 n -2LmnA -2v o.oJ + 7 o.ayI+ 1 0.015+1 Ccwemhm Rates (DC Volta): UbnnmmA
*oMn Irn " -x0* -1v 0.06 + 5 o,1m+ 5 o.m+*
+Afterpu&b"tto" or busrrminx.
*I" wldktigitnwdr. counts- *2 bcept *t4 0" x-a rangeafterZerobIg,.
CONFRXJRATlON: Automatic 2- or 44erminal.
MAXM"M ALLOWABLE INT'DT: 36oV peak or 250, nns.
BEN~NdEADWG RATE: 3 readb&sRand except 2OMOrange, 1 reading/ tReadt&&nd. V.&m at .%Hz.
Addrw Modes: TALK ONLY and ADDRESSABLE.
TRMS AC VOLTS (Option 19.50) FRONT PANEL PROGRAMS
w/a Eigiw ACCURACY YEAR),
(1 0 Clear - Camels program mode.
*~%rd*+cwnal 1 Non-volattle RAM st.,,age - Store programs 3.4.5 and 8 data in NVRAM
2 MuhI lex - Defeata input amplifier multlplexlw
3 IEEE1w mode - ADDRESSABLE and TALK ONLY entry.
4 Lhe frequency - Selects5si7. or tQH2 operation.
5 Caltbntlo" - Perfonnr digital calibration.
6 Extended prognms - Enabler entry to aptiwal expanricn rogams.
7 Data lq&Sf7- Allows 1co.readlq storage *t 9 pm*amma PO rate% alw
le
stores highest, lowest and average reading.
,I" rv..di#t mode. divide cmlm error by 10. Above Irn". 8 Dla~rtoatice- TmublesbooHng aid and self-test.
9 Trlggp: - Enablesfmnt panel or extemal tripgeflw.
TEMPERAnJRE coEFFIclBNr loo-ISOC & 2ax5owz Leu tha" rt(O.lX
applicable accuracy speeificatlonl/`C. GENERAL
RESPONSE:True mot mea" squarr, AC coupled. DISPLAY: SIX 0.5" LED digiti with de&md oint, exponent and polarity.
CREST FACTOR (ratio of peak to rmsl: Up to 3:l allowable. Function and IEEEbus status also displayec?
INPUT IMPEDANCE: 2Mn shunted by lea than 75pF. - -.
MAXIMUM ALLOWABLE fNf%T: IWOV peak. IO'V.Hz. ISOLATION: Input LO to IEEELO or owe?It&round: 5ooV A, 5 x lo'
BENCH READING RATE: 3 rexlii/seco"d. V*M; gnater tba" lO*Il paralleled ! y X'@F.
CMRRz Greater than @dB at DC, 50 or 6OHz (with IkR in either lead). WARMup: 1 hour to rated accuracy.
BANDWIDTH: -3dB at 2SOkHztypical. OzTpG ENVIRONMENT: O"-5WC. 0% to 80% relative humidity up
.- -- 0-.
DC AMPS (Option 1950) STORAGE ENVIRONMENT: -25' to 65%.
w/1 wa, -TURF POWER: 10542sv or 21&?50v (internal switch &ctEd), 5042 to 4wfiz.
ACamAcY (1YEAR,,* coEFRm MAnMuM 24V.A maximum. `9&llOV and lBo22OV version avatlable upon reauest.
RESO *Pkd~+rounw *,%rd*+cemw/`c VOLTAGE
RANGE LvnON 18'28'C wwc b 28Be5oQc BmEN CONNECTORS: Amlog: Stitch selectablefront or rear, 5wa; Sold piated
binding posts. Digttal: `Tririgger" input and %ltmeter Complete" output
20!A me. 0.14+40* 0.01+7. 0.03" on rear panel, BNCs.
?m#t`4 InA W-9+10 0.01+0.5 0.25v
2m.4 lti 0.09+10 0.0110.5 0.25v DIMENSIONS, WEIGHT: 127mm l&h X 216mm wide X 35%~" deep (5"
x&A 0.09+10 0.01+0.5 02.5v X 8'S" X 14%").Net wetit 3.2kp. (7 Ibs.).
222, 0.09+10 0.01+0.5 0.28v
2.4 lOP.4 O.C9+lO o.ol+o.5 1 "
t,n 4vdkit mode,coun*- *:2 kxapl 24 0" 2Qx.4
nnxe after zeroinn).
t4fm pushbutton buszeroins.
or
OVERLOAD PROTECTION: 2A fuse LXOV), externally accessible
BENCH READING RATE: 5 r&i"gs/recond.
Safety Precautions
`The following safety precautions should be observed before using Users of this product must be protected from electric shock at all
this product and any associated instrumentation. Although some in- times. The responsible body must ensure that users are prevented
struments and accessories would normally be used with non-haz- access and/or insulated from every connection point. In some cases,
ardous voltages, there am situations where hazardous conditions connections must be exposed to potential human contact. Pmduct
may be present. users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
This product is intended for use by qualified personnel who recog- at or above 1000 volts, no conductive part of the circuit may be
nize shock hazards and are familiar with the safety precautions re- exposed.
quired to avoid possible injury. Read the operating information
carefully before using the product. As described in the International Electrotechnical Commission
@EC) Standard IEC 664, digital multimeter measuring circuits
The types of product users am: (e.g., Keithley Models l75A, 199,ZOOQ 2001, 2002, and 2010) are
Responsible body is the individual OI group responsible for the use Installation Category II. All other insmnnents' signal terminals are
and maintenance of equipment, for ensuring that the equipment is Installation Category I and must not he connected to mains.
operated within its specifications and operating limits, and for en-
suring that operators BT~adequately trained. Do not cmmect switching cards directly to unlimited power circuits.
They am intended to be used with impedance limited sources.
Operators use the product for its intended function. They must be NEVER connect switching cards directly to AC mains. When con-
trained in electrical safety procedures and proper use of the instm- necting sources to switching cards, install protective devices to lim-
ment. They must be protected from electric shock and contact with it fault current and voltage to the card.
hazardous live circuits.
Before operating an instrument, make sure the line cord is connect-
Maintenance personnel perform routine procedures on the product ed to a properly grounded power receptacle. Inspect the connecting
N keep it operating, for example, setting the line voltage or mplac- cables, test leads, and jumpers for possible wear, cracks, or breaks
ing consumable materials. Maintenance procedures are described in before each use.
the manual. The procedures explicitly state if the operator may per-
form them. Otherwise, they should be performed only by service For maximum safety, do not touch the product, test cables, or any
personnel. other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
Service personnel are trained to work on live circuits, and perform any capacitors before: connecting or disconnecting cables or jump-
safe installations and repairs of products. Only properly trained ser. ers, installing or removing switching cards, or making internal
vice personnel may perfm'm installation and service procedures. changes, such as installing or removing jumpers.
Exercise extreme caution when a shock hazard is present. Lethal Da not touch any object that could provide a current path to the
voltage may be present on cable connector jacks or tat fixtures. The common side of the circuit under test or power line (earth) ground.
American National Standards Institute (ANSI) states that a shock Always make measurements with dry hands while standing on a
hazard exists when voltage levels greater than 3OV RMS, 42.4V dry, insulated surface capable of withstanding the voltage being
peak, or 60VDC are present. A good safety practice is to expect measured.
that hazardous voltage is present in any unknown circuit before
measuring.
The instrument and accessories must be used in accordance with its The WARNING heading in a manual explains dangers that might
specifications and operating instmctions or the safety of the equip- result in personal injury or death. Always read the associated infor-
ment may be impaired. mation very carefully before performing the indicated procedure.
Do not exceed the maximum signal levels of the instruments and ac- The CAUTION heading in a manual explains hazards that could
cessories, as defined in the specifications and operating informa- damage the instrument. Such damage may invalidate the warranty.
tion, and as shown on the instrument or test fixture panels, or
switching card. Instrumentation and accessories shall not be connected to humans.
When fuses are used in a product, replace with same type and rating Before performing any maintenance, disconnect the line cord and
for continued pmtection against fire hazard. all test cables.
To maintain protection from electric shock and fire, replacement
Chassis connections must only be used as shield connections for
components in mains circuits, including the power transformer, test
measuring circuits, NOT as safety earth ground connections.
leads, and input jacks, must be purchased from Kcithley Ins&w
mats. Standard fuses, with applicable national safety approvals,
If you are using a test fixture, keep the lid closed while power is ap-
may be used if the rating and type are the same. Other components
plied to the device under test. Safe operation requires the use of a
that are not safety related may be purchased from other suppliers as
lid interlock.
long as they are equivalent to the original component. (Note that se-
lected pats should be purchased only through Keithley Instruments
lfa@ screw is present, connect it to safety earth gmund using the
to maintain accuracy and functionality of the product.) If you are
wire recommended in the user documentation.
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.
Then symbol on an btstmment indicates that the user should re-
fer to the operating instructions located in the manual.
To clean an insuument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
TheA symbol on an instrument shows that it can source or mea-
cleaner directly to the instrument or allow liquids to enter or spill
sure 1000 volts or more, including the combined effect of normal
on the instrument. Products that consist of a circuit board with no
and c~mrn~n mode voltages. Use standard safety precautions to
case or chassis (e.g., data acquisition board for installation into a
avoid personal contact with these voltages.
computer) should never require cleaning if handled according to it-
stmctions. If the board becomes contaminated and operation is af-
fccted, the board should be returned to the factory for proper
cleaning/servicing.
Rev. 7.199
TABLE OF CONTENTS
Paragraph Title Page
SECTION 1 GENERAL INFORMATION
1.1 Introduction ................................................................................. l-l
1.2 Model196Features ........................................................................... l-l
1.3 WarrantyInformation ......................................................................... l-l
1.4 Manual Addenda ............................................................................. l-l
1.5 Safety Symbolsand Terms ..................................................................... l-1
1.6 Specifications. ............................................................................... l-l
1.7 Unpackingandlnspection ...................................................................... 1-2
1.8 PreparationForUse ........................................................................... 1-2
1.8.1 LinePower ........................................................................ . ....... l-2
1.8.2 LineVoltageSelection ....................................................................... 1-2
1.8.3 LineFrequency ............................................................................. 1-2
1.8.4 IEEEPrimaryAddress ....................................................................... l-2
1.85 Model185OptionPreparation.. .............................................................. l-2
1.9 RepackingForShipment ....................................................................... l-2
1.10 Using the Model 195 Instruction Manual .......................................................... 1-3
1.11 Accessories .................................................................................. l-3
1.11.1 Model1301TemperaturaProbe ............................................................... l-3
1.11.2 ModellOlSRackMountingKit ................................................................ 1-3
1.11.3 Model1600AHighVoltageProbe.. ........................................................... 1-3
1.11.4 Model1641KelvinTestLeadSet .............................................................. 1-3
1.11.5 Model165150-AmpereShunt ................................................................ 13
1.11.6 Model1681Clip-OnTestLeadSet ............................................................. 1-3
1.11.7 Model1682ARFProbe ...................................................................... 13
1.11.8 Model1683UniversalTestLeadKit ............................................................ 1-3
1.11.9 Model 1685 Clamp-On AC Current Probe ....................................................... l-3
1.11.10 Model 1691 General Purpose Test Lead Kit. ..................................................... l-3
1.11.11 Model 1950 AC Voltage; AC and DC Current Option ............................................. 1-3
1.11.12 Model7008IEEE-488Cable.. ................................................................ l-3
SECTION 2 BASIC OMM OPERATION
2.1 Introduction ................................................................................. 2-l
2.2 FrontPanelFamiliarization ..................................................................... 2-1
2.2.1 Controls ................................................................................... 2-1
2.2.2 Terminals .................................................................................. 2-2
2.2.3 Displayandlndicators ....................................................................... 2-2
2.2.4 TiltBail .................................................................................... 2-2
2.3 RearPanelFamiliariration ...................................................................... 2-2
2.3.1 ConnectorsandTerminals ................................................................... 2-3
2.3.2 INPUTSSwitch ............................................................................ 2-3
2.3.3 Fuses ..................................................................................... 2-3
2.4 Power-UpProcedure .......................................................................... 2-3
2.5 DisplayMessage .............................................................................. 24
2.5.1 OverflowIndication.. .......................................................................
2.5.2 NoOptionMessage ......................................................................... El
ControlSelection ............................................................................. 2-6
Zl Function .................................................................................. 2-5
2:6:2 Range .................................................................................... 2-6
2.6.3 UsingZero ................................................................................. 2-5
2.6.4 Filtering ................................................................................... 2-6
2.6.5 DisplayResolution.. ........................................................................ 2-7
2.6.6 InputTerminalSelection ..................................................................... 2-7
2.7 Triggering.. ................................................................................. 2-7
i
TABLE OF CONTENTS (CONT.)
2.7.1 FrontPanelTriggering ....................................................................... 2-7
2.7.2 ExternalTrigger ............................................................................ 2-7
2.7.3 VoltmeterComplete.............................................................~ ........... 2-8
2.7.4 TriggeringExample ......................................................................... 2-8
2.8 BasicMeasurements.. ........................................................................ 2-9
2.8.1 OCVoltageMeasurements ................................................................... 2-9
2.8.2 ResistanceMeasurements .................................................................. 2-10
2.8.3 ACVoltageMeasurements .................................................................. 2-11
2.8.4 OCCurrentMeasurements .................................................................. 2-11
2.8.5 ACCurrentMeasurements .................................................................. 2-11
2.9 TRMSConsiderations ........................................................................ 2-12
2.9.1 TRMSMeasurementComparison ............................................................ 2-12
2.9.2 CrestFactor .............................................................................. 2-13
SECTION 3 FRONT PANEL PROGRAMS
Introduction ................................................................................. 3-l
t: ProgrammingControls ........................................................................ 3-1
3:3 Front Panel Program Display Messages .......................................................... 3-1
3.4 ProgrammingNotes ........................................................................... 3-1
3.5 ProgramDescription .......................................................................... 3-3
3.5.1 ProgramO.Clear ............................................................................ 3-3
35.2 Program 1. Non-Volatile Storage .............................................................. 3-3
3.5.3 Program2.Multiplex ........................................................................ 3-3
3.5.4 Program 3. IEEE Address and Talk-Only Mode ................................................... 33
3.5.5 Program4.LineFrequency ................................................................... 3-4
3.5.6 Program 5. Digital Calibration ................................................................. 3-4
3.5.7 Program6.Expansion ........................................................................ 3-5
3.5.8 Program7.OataLogger.. ................................................................... 3-5
3.5.8 ProgramS.Oiagnostics ...................................................................... 3-7
3.5.10 ProgramS.TriggerMode .................................................................... 3-8
3.6 ProgremmingScalingFactors .................................................................. 3-8
SECTION 4 IEEE-488 OPERATION
4.1 Introduction ................................................................................. 4-l
4.2 BusDescription .............................................................................. 4-l
4.3 IEEE488BusLines ........................................................................... 4-2
4.3.1 SusManagementLines ...................................................................... 4-2
4.3.2 HandshakeLines ........................................................................... 4-2
4.3.3 DataLines ................................................................................. 4-3
4.4 BusCommends.. ............................................................................ 4-3
4.4.1 UnilineCommands .......................................................................... 4-3
4.4.2 UnivenalCommands ........................................................................ 4-3
4.4.3 AddressedCommands ...................................................................... 4-4
4.4.4 UnaddressCommands ...................................................................... 4-4
4.4.5 Device-DependentCommands ................................................................ 4-4
4.5 Command Codes ............................................................................. 44
4.6 CommandSequence .............................................................. . ........... 4-4
4.6.1 Addressed Command Sequence ............................................................... 46
4.6.2 UniversalCommandSequence ............................................................... 4-6
4.8.3 Device-Dependent Command Sequence ....................................................... 4-6
4.7 Hardwareconsiderations ...................................................................... 4-6
4.7.1 Typical Controlled Systems .................................................................. 4-6
4.7.2 BusConnections.. ......................................................................... 4-6
4.7.3 PrimaryAddressProgramming ................................................................ 4-8
4.7.4 Talk-Only Mode ............................................................................ 49
4.8 Softwareconsiderations ....................................................................... 4-9
4.8.1 Controller Interface Routines ................................................................. 4-9
4.8.2 HP-85BASlCStatements .................................................................... 4-9
ii
TABLE OF CONTENTS (CONT.1
4.03 InterfacaFunctionCodas ................................................................... 410
4.8.4 Model 195 Interface Commands .............................................................. 4-10
4.9 General Bus Command Programming ........................................................... 411
4.9.1 REN (Remote Enable) ...................................................................... 4-11
4.9.2 IFClInterfaceClear) ........................................................................ 4-11
4.9.3 LLOlLocalLockout) ....................................................................... 4-12
4.8.4 GTL(GoToLocall ......................................................................... 4-12
4.9.5 DCL(DeviceClear) ......................................................................... 4-12
4.9.6 SDC (Selective Device Clear) ................................................................ 412
4.9.7 GETlGroupExecuteTriggsrJ ................................................................ 4-13
4.9.8 Serial Polling (SPE, SPD) ................................................................... 413
4.10 Device-Dependent Command Programming ..................................................... 4-13
4.10.1 Execute(X) ............................................................................... 4-14
4.10.2 FunctionfF) ...................................................................... . ....... 4.14
4.10.3 Range(R) ................................................................................ 4-14
4.10.4 Rate(S) .................................................................................... 4-16
4.10.5 ZeroCommandIZ) ......................................................................... 4-17
4.10.8 Filter. .................................................................................... 4-17
4.10.7 Triggering (Tl ............................................................................. 4-17
4.10.8 EOIIK) ................................................................................... 4-18
4.10.9 Multiplex(A) .............................................................................. 4-18
4.10.10 Delay(W) ................................................................................ 4-18
4.10.11 StatusWord ........................................................................... 4-19
4.10.12 SRQ Mode (M) and Status Bvte Format. ...................................................... 4-20
4.10.13 BufferCommand (Qand El ................................................................. 4-21
4.10.14 DateFormat ........................................................................... 4-22
4.10.15 DigitalCalibration ......... ..i .......................................................... 4-23
4.10.16 Non-VolatileMemorvStoragefL) ............................................................ 4-24
4.10.17 SelfTest .............................................................................. 4-24
4.10.18 ProgrammingTerminator(Y). ............................................................ 4-24
4.10.19 HitBunonlH) ............................................................................. 4-26
4.10.20 Display(D) ............................................................................... 4-25
4.11 FrontPanelErrorMessages ................................................................... 426
4.11.1 IDDCError ............................................................................... 4-26
4.11.2 IDDCOError .............................................................................. 4-26
4.11.3 NoRemoteError .......................................................................... 4-26
4.12 ReadingRates .............................................................................. 4-27
SECTION 6 PERFORMANCE VERIFICATION
5.1 Introduction ................................................................................. 5-l
5.2 EnvironmentalConditions ...................................................................... 51
5.3 RecommendedTestEquipment ................................................................. 6-l
5.4 InitialConditions .............................................................................. 5-l
5.5 Verificationprocedure ......................................................................... 5-l
55.1 DCVoltageAccuracyCheck .................................................................. 5-2
5.5.2 ResistanceAccuracyCheck .................................................................. 52
5.5.3 AC Voltage Accuracy Check (with Model 1950 Option) ............................................ 6-3
5.54 DC Current Accuracy Check (with Model 1950 Option) ........................................... 6-4
5.5.5 AC Current Accuracy Check (with Model 1950 Option) ........................................... 6-6
SECTION 6 THEORY OF OPERATION
6.1 Introduction .................. . .............................................................. 6-l
Overall Functional Description ................................................................. 8-1
2 AnalogCircuitF/ .............................................................................. 6-l
6:3.1 InputSwitchingandMultiplexer .............................................................. 6-l
6.3.2 InputBufferAmpiifier ....................................................................... 8-3
6.3.3 -2VReferenceSource ....................................................................... 6-3
6.3.4 AIDConverter ............................................................................. 6-3
iii
TABLE OF CONTENTS (CONT.1
6.4 DigitalCircuitry ............................................................................... 8-5
6.4.1 Microcomputer Block Diagram ................................................................ 8-5
6.4.2 MemoryMapping ........................................................................... 65
6.4.3 AddressDecoding.. ........................................................................ 6-5
6.4.4 MicrocomputerReset ....................................................................... 6-7
6.4.5 6522VIA .................................................................................. 6-7
6.4.6 IEEElnterface ............................................................................... 6-7
6.4.7 Display Board .............................................................................. 6-7
6.4.8 Serial-Parallel Conversion .................................................................... 6-7
PowerSupply ................................................................................ 6-8
:i Modell950AClCurrentOption ................................................................. 6-8
6:7 Circuit Operation During Measurements. ......................................................... 6-8
8.7.1 DCVoltageMeasurement .................................................................... 8-8
6.7.2 Circuit Operation During Resistance Measurements .............................................. 6-9
6.7.3 2- and 4-Terminal Resistance Considerations ................................................... 6-l 1
6.7.4 Circuit Operation During Model 1950 Option Measurements ....................................... .8-11
SECTION 7 MAINTENANCE
7.1 Introduction.. ............................................................................... 7-l
7.2 LineVoltageSelection ......................................................................... 7-1
7.3 FuseReplacement ............................................................................ 7-l
7.3.1 LineFuse...............................................................................~ .. 7-1
7.3.2 AmpsFuse ................................................................................ 7-2
7.4 Model 1950 AC/Amps Option Installation ........................................................ 7-2
7.5 CaObration ................................................................................... 7-3
7.5.1 Recommended Calibration Equipment ......................................................... 7-3
7.5.2 Environmental Conditions .................................................................... 7-3
7.5.3 WarmUpPeriod ........................................................................... 7-3
7.5.4 DCVoltageCalibration ...................................................................... 7-4
7.5.5 ResistanceCalibration ....................................................................... 74
7.5.6 ACVoltegeCalibration ...................................................................... 7-5
7.5.7 AC and DC Current Calibration ................................................................ 7-8
75.8 Non-Volatile Storage of Calibration Constants. .................................................. 7-6
7.5.9 CalibrationJumpers ......................................................................... 7-8
7.8 Special Handling of Static Sensitive Devices ...................................................... 7-7
7.7 Disassembly Instructions ....................................................................... 7-7
7.8 Troubleshooting ............................................................................ 7-0
7.8.1 RecommendedTestEquipment ............................................................... 7-8
7.8.2 Power-Up Self Diagnostics ................................................................... 7-8
7.83 SelfDiagnosticProgram ..................................................................... 7-9
7.8.4 PowerSupplyChecks ....................................................................... 7-9
7.8.5 A/DConverrerandDisplay ................................................................... 7-9
7.8.8 Input Attenuator and Ohms Source Checks ..................................................... 7-9
7.8.7 Input Multiplexer and Buffer Amplifier ......................................................... 7-9
7.8.8 Digital Circuitry. ............................................................................ 7-9
7.8.9 Modell950AC/AmpsOption.. .............................................................. 7-9
7.8.10 BufferAmplifierGainChecks ................................................................ 7-15
SECTION 8 REPLACEABLE PARTS
8.1 Introduction ................................................................................. El
8.2 PartsList .................................................................................... 8-I
8.3 Orderinglnformation .......................................................................... 9-l
8.4 Facton/Service ............................................................................... 8-l
8.5 Schematic Diaarams and Component Location Drawinas ........................................... 8-l
iv
LIST OF TABLES
Table Title Page
2-l Power Up Test Error Messages .................................................................. 2-4
2-2 RangeDetermination .......................................................................... 2-5
2-3 FilterModes.. ................................... ............................................ 2-6
2-4 Maximum Input Values ........................................................................ 2-g
2-5 Resistance Range Output Values ............................................................... 2-10
2-6 Four-wire Maximum Allowable Test Lead Resistance .............................................. 2-11
2-7 Comparison of Average and TRMS Meter Reading. ............................................... 2-12
3-l Front Panel Program Summary ................................................................. 3-l
3-2 General Front Panel Program Messages .......................................................... 3-l
3-3 Program 3. IEEE Parameters .................................................................... 3-4
3-4 Program 7. Logging Rates. ..................................................................... 3-7
3-5 ProgremE.Tests ............................................................................. 3-7
4-l IEEE-488 Bus Command Summary .............................................................. 4-3
4-2 Hexadecimal and Decimal Commend Codes ...................................................... 4-4
4-3 Typical Addressed Command Sequence .......................................................... 4-6
4-4 Typical Device-Dependent Command Sequence ..................................................... 4-6
4-5 IEEEContactDesignations.. ................................................................... 4-8
4-6 HP-85 IEEE-488 BASIC Statements ............................................................ 4-10
4-7 Model 195 Interface Function Codes ............................................................ 4-10
4-8 IEEECommandGroups ....................................................................... 4-11
4-9 GeneralEusCommands.. .................................................................... 4-11
4-10 Default Conditions (Status Upon Power Up or After SDC or DCLI ................................... 4-12
4-11 Device-Dependent Command Summary ......................................................... 4-15
4-12 RangeCommands.. ......................................................................... 4-16
4-13 Rats Commands ............................................................................. 4-17
4-14 FilterCommends ............................................................................ 4-17
4-15 StatusWordFormats ........................................................................ 4-19
4-16 SRQMaskCommands ....................................................................... 4-20
4-17 Status Byte Interpretation ..................................................................... 4-21
4-18 Buffer Rate Commend Parameters ............................................................. 4-22
5-l Recommended Test Equipment for Performance Verification ........................................ 5-l
5-2 LimitsforDCVoltsgeVeyiiication ............................................................... 5-2
5-3 Limits for Resistance Venfrcation ................................................................ 5-3
5-4 Limits for AC Voltage Verification ............................................................... 5-4
5-5 Limits for DC Current Verification ................................................................ 5-4
5-8 Limits for AC Current Verification ............................................................... 5-5
6-l Integration Delay Periods ... ................................................................... 6-4
6-2 Model 195 Memory Mapping ................................................................... 6-5
7-l LineVoltageSelection ......................................................................... 7-l
7-2 LineFuseSelection ........................................................................... 7-l
7-3 Recommended Test Equipment for Calibration .................................................... 7-3
7-4 DC Voltage Calibration Parameters .............................................................. 7-4
7-5 Psramstersfor Resistance Calibration. ........................................................... 7-4
7-6 AC Voltage Calibration Parameters .............................................................. 7-5
7-7 Model 1950 Frequency Compensation Parameters ................................................. 7-5
7-8 Current Calibration Parameters ................................................................. 7-6
7-9 StaticSensitiveDevices ....................................................................... 7-7
7-10 Recommended Troubleshooting Equipment ...................................................... 7-8
7-11 FETand Relay Switching Sequence for Various N Modes .......................................... 7-10
7-12 ProgramE.Tests ............................................................................ 7-12
7-13 PowerSupplyChecks ........................................................................ 7-13
7-14 AIDConvsrterChecks ....................................................................... 7-13
LIST OF TABLES (CONT.1
7-15 DisplayBoardChecks ................................................
7-16 DCAnenuatorChecks ................................................
7-17 Dhmsand -2V Reference Source Checks ................................
7-16 Digital Circuitry Checks ...............................................
7-19 Model 1950 Option Checks. ...........................................
7-20 Buffer Amplifier Gain Checks .......................................... ...... 7-16
8-1 Index of Model 195 Schematics and Component Layouts .................. ....... 8-l
8-2 Mother Board 196-103, Parts List ....................................... ....... 8-3
8-3 Display Board 195-113, Parts List ....................................... ....... 8-7
8-4 Model 1950 AC Option 1950-153, Parts List .............................. ....... 8-8
LIST OF ILLUSTRATIONS
Figure Title Page
l-l InstrumentPackaging.. ....................................................................... 1-2
2-1 Modell95FrontPanel ......................................................................... 2-1
2-2 Model195RearPanel ......................................................................... 2-2
2-3 External Trigger Input Pulse Specifications ........................................................ 2-8
2-4 Voltmeter Complete Output Pulse Specifications .................................................. 2-8
2-5 External Trigger Connections ................................................................... 2-8
2-6 DCVoltageMeasurements ..................................................................... 2-9
2-7 Two-Terminal Resistance Measurement, ........................................................ 2-10
2-8 Four-Terminal Resistance Measurement ......................................................... 2-10
2-9 ACVoltageMeasurement ..................................................................... 2-11
2-10 DC and AC Current Measurement ............................................................... 2-12
3-1 Front Panel Program Controls .................................................................. 3-2
4-l IEEEBusConfiguration ........................................................................ 4-l
4-2 IEEEHandshakeSequence ..................................................................... 4-Z
4-3 CommandCode .............................................................................. 45
4-4 SvstemTvpes ................................................................................ 4-7
IEEE-488Connector ........................................................................... 4-7
i-i IEEE-488Connections ......................................................................... 4-7
4-7 Rear Panel of Model 195 Showing IEEE Connector ................................................. 4-7
4-8 ContactAssignments ......................................................................... 4-8
4-9 Tvpical IEEE-488 Bus Driver (One of 16) .......................................................... 4-8
4-10 SRQ Mask and Status Byte Formats ............................................................ 4-21
4-11 DataFormat ................................................................................ 4-23
4-12 Hit Button Command Numbers ................................................................ 4-25
4-13 IEEEDisplayErrorMessages ................................................................... 4-26
5-1 Connections for Voltage Verification ............................................................. 5-2
5-2 Connections for Verification of ZOSI,2003, and 2kB Ranges ......................................... 6-3
53 Connections for Verification of 2OkD Through 20MD Ranges. ........................................ 5-3
5-4 Verification Connections for Current ............................................................. 5-4
6-1 BasicBlockDiagram .......................................................................... 6-2
6-2 Simplified Schematic of the Multiplexer .......................................................... 8-3
63 Simplified Schematic of the Input Buffer Amplifier ................................................. 6-3
6-4 Simplified Schematic of the -2V Reference Source. ............................................... 6-4
6-5 Simplified A/D Converter Schematic ............................................................ 6-4
6-6 A/D Converter Integrator Output Waveform ...................................................... 6-4
6-7 Simplified Microcomputer Block Diagram ........................................................ 6-6
6-6 Ciruit Operation During DC Voltage Measurements ................................................ 6-9
6-9 FET Switching Sequence During DC Voltage Measurements ........................................ 6-9
6-10 Resistance Measurement Simplified Circuit For 20-200kD Ranges ................................... 6-10
6-11 FET Switching Sequence for 2OD. 2000 and 2kD Ranges. .......................................... 6-10
6-12 FET Switching Sequence for 20kD and 200kD Ranges ............................................. 6-11
6-13 FET Switching Sequence for 2MD an