Keithley 135, 176, 1765 Service manual

Service Manual

Model 1765

Contains Servicing/Calibration Information for

Models 136 and 176

Test Instrumentation Group

Keithley Instrumenthlnc.

28773 Aurora Road
Cleveland, Ohio 44139
(216) 248X400 . Fax: [phone]

BZiii;

Kaithley Instruments. Inc.
28775 Aurora Road/Cleveland. Ohio 44139/[phone]

WARRANTY

We warrant each of our products to be free from defects in material
and workmanship. Our obligation under this warranty is to repair
or replace any instrument or partthereof which, within a year after
shipment, proves defective upon examination. We will pay local
domestic surface freight costs.

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 shipping instructions.

REPAIRS AND
CALIBRATION

Keithley Instruments maintains a complete repair and calibration

service as well as a standards laboratory in Cleveland, Ohio.

A Keithley service facility at our Munich, Germany office is

available for our customers throughout Europe. Service in the
United Kingdom can be handled at our office in Reading. Addition­ally, Keithley representatives in most countries maintain service
and calibration facilities.

To insure prompt repair or recalibration service, please contact
your local field representative or Keithley headquarters directly

before returning the instrument. Estimates for repairs, normal
recalibrations and calibrations traceable to the National Bureau of
Standards are available upon request.

Keithley Ins&nents, Inc.128775 Aurora Road/Cleveland, Ohio 44139/U.S.A./(216) 248400/T&x: 985469

WEST GERMANY: Keithiey Inshumentr GmbH/Heiglhofstrasse S/D-8003 Mitnchen 70/@89) 7l4-4&6.5/Telex: 52121 60

GREAT BRlTAIN: Keitbley Instruments, Ltd./l, B&ton RoadlCEReadi~ Berkshire RG2 ONU(O734) 86 12 87/T&~: 847047
WCE: Keithley htrvments SARL12 Bis, Rue Leon Blum/B.P. 60/91121 Palaiseau C&.x/(6) 011,51,55/Tekx: 600933F
NEIHERLANDS: Keithley Instrvments B.V./Leid&raatweg 149/Postbus 1190 /NL-WcerderJ(O34EO) 13 M3/Telex: 40 311
SWITZERLAND: Keithfey Instruments SA/Filiale DttbendorflKriesbachstr. 4fCH-8603 D&zndorf/Ol 82194 44/T&x: 57 536
AUSTRIA: Keitbley Instruments HandeL+Gesekbaft m.b.H.IDbbliier Hauptstr. 32/A-119C Wien/O222 314 289/T&x: 13 45 W

TABLE OF CONTENTS
SECTION
1

1-l
1-4

1-6
1-E
l-i0

l-12
1-14

2
2-l
2-2

2.10
2-13

3
3-1
3-6

3.12

4
4-I
4-2
4-9

5
5-l
5-2
5-5
5-10
5-13

5.17
5-18

TITLE

GENERAL INFORMATION

iNTRODUCTlON

FEATURES..
WARRANPIINFORMATION
MANUAL ADDENDUMS
SAFETY SYMBOLS AND TERMS
UNPACKING AND INSPECTING
SPECIFICATIONS

r\CCC~~““lC~

GENERAL
MUTUAL ACCESS
MODEL 135 EXCLUSIVE ACC

MODEL 176 EXCLUSIVE ACC

rc”r”“I”I~NLc “CnlrlLAI I”N

GENERAL
MODEL 135 PERFORMANCE VERIFICATION
MODEL 176 PERFORMANCE VERIFICATION

lrlC”“T vr “rEI(CIII”N .............................................................

GENERAL
MODEL 135 OVERALL FUNCTIONAL DESCRIPTION

MODEL 176 OVERALL FUNCTIONAL DESCRIPTION ...............................

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,ORlES

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MAINTENANCE (TROUBLESHOOTING. CALISRATIONI.

GENERAL
MODEL 135
TROUBLESH
MODEL 176 CALIE
MODEL 176 TROU
CURRENT FUSE RE
MODEL 1766 TROuurc:

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CALIBRATION

DOTING

3RATION
IELESHDOTING
IPLACEMENT

“-‘-1HOOTING

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ESSORIES.,

ESSORIES

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PAGE

1-l

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6
6-l

REPLACEABLE PARTS

GENERAL

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MODELS 135/l 76

GENERAL INFORMATION

Model 135/l 76 Service Manual

Section 1. General Information

l-l. INTRODUCTION

l-2, The Modeis 135/176 are low cos,. 4-l/2 d~gt,.
LCD dtsplav digatal muitimeters. The two me!ers are
unfque in that they are sfm~lar in electromc design ye,
different I” case design. The most obvious dhiference 1s
the phvwal dilference. The 176 is designed tnro a more
,rad,I,onal DMM case whlie the 135 is designed #“to a
hand held case. The 176 has more current ranges and a

w,der frequency span for ACV. They both have a basx DC

accuracy of 0 05% and also a basic OHMS accuracy of

0.2%. They also bastcallv have the same A/D converter
l-3. Thus manual 1s a comeinatmn of sewce rnformatjon

for both DMM’s (1 35 and 176) I, contans tnformarlon
necessary to maintain. caitbrate and troubleshoa Ihe

Model 135 and the Model 176,

1-4. FEATURES

l-5. The 135 and 176 have many d,s,,nc, fearures and

advantages some 01 which are l,s,ed below:

.

A 20000 count I,.‘-1 12 d,g,t, Iiqu,d crvstal dtspiav.

[LCD) ,w,h large 0 6 ,nch numerals The 176 has

functnn and fange ,nd,cators. The 135 and 176

have a low ba,,eiv lndlcator that hghts when there

IS less than 10% battery life rema,“i”g. Appro­prtale declmai point and minus stgn (~1 areaisodls­played, posirive polarttv IS ,mplied.

.

The Model 135 and 176 are bull, rugged. The hand

held case and the bench s,ze case are molded from

impact-res~stan, plastic. Effective ,npu, profection

prevents damage on ail functmns.

Htgh lrequencv (RFI probe allows YOU< 3MM !a
measure from 0~25V 10 30V rms AC ow a Fred
quency range from 1OOKHr 10 iOOMHz

50 ampere wrren, Shun, aiiow~ YOU, DMM 10

measure up 10 50A. AC or DC
Clamp on AC curie”, probe al,ows vour 9M11 !o

measure up 10 200A rms AC
Htgh Voiiage Probe allows your DMM ,c reas;‘r

from 1 OOOV 10 40KV DC

NOTE

l-6. WARRANTY INFORMATION

1-7~ The warranty is gwen on ,he instde front cover ci
,h,s instruction ma”“al~ If there IS a need 10 exercise ine
warranty contact the Kenhlev Representawe 10 vour area
to de,etm,“e the proper act,o” to be take” Kelrhiey slain­fans serwce fac,l,,les I” the Untted Klngaom ‘.“,esr
Germany and I” ,he UnIted States Check ,ne !ns~de.roni
cover of lhls manual for addresses

l-8. MANUAL ADDENDUM8

l-9, ,mpr~vements or changes tha, affec, iqese ~nsfru­ments which occ”r affer pil”,l”g of the I”s,rdc,,on
Manual wlil be explained on anaddendum sheelartacnea
to the jnside back cover,

.

The 176 pushbuttons are color coded to the front
pane, for qwck and easy selecr~on of functton and
range. The 135 rotarv fun&on and range swlch
are easdy pos,r,oned to color coded functtons and
ranges. The decimal pan, is automatlcallv pow
tloned by the range pushbu,,on/rofarv switch. The

176 dlsplav annunciators indicate rhe selected
function and range. Improper range and function
comb,na,,ons are lndlcated bvcontradalng func­bon and/or range annunc,alors appear,ng a, the
same rime.

.

Stare of the arr technology and stable prectsio”
components have been used I” these two DMM’s
to prov,de iong term accuracy and m,“,mtze main­tenance. Calibration IS required only once a year.
If aikal,“e battertes are used /SIX C cells I” the 176
or one 9 volt ceil for the 1351 battery IIfe can be as
long as 1000 hours for the I 76 and 100 hours for
the 135

.

Opttonal accessories can be ordered To extend the
measurement capabtlttvof me 135 and 176. Some
of these accessor,es are’

l-10. SAFETY SYMBOLS AND TERMS

1-l 1~ Safe,” symbols used ,n lhis manual are as foilows

The symbol&an rhe ~nstrumen, denores lha, ihe user
should refer 10 the operarIng insfrucf~ons

The symbol 1 on the ~nswumen, denotes rhat I OCOV
or more may be present on the ,erminai~s,

The WARNING used in th,s manual explains dangers
that could resulf tn personai tn,urv or dean

The CAUTION used I” ,h,s manual expiains hazar?s :?a,
could damage the ~nsrrumen,,

l-12. UNPACKING AND INSPECTION

1 13 The Models~l 35 and 1 76 were carelullv 8”speclea
borh mecha”,ca,,v and eiec,wallv before snipmenl “pan
rece,w”g either or bolh of these instrumeni~. unpack a!!
items from the sh,pp’“g container and check for a”” 00~5~
ous damagethat may have occurred during ira”s8, Reoor:
any damage 10 the shtppmg age”,, Retain and use :hi
orig,“a, packag,ng ma,er,a,s ,f reshIpme”, 15 “ecessar,
The followmg ,,ems are sh,pped wr,h alI ‘35 a”3 : :<

orders~

GENERAL INFORMATION

MODELS 135/176

A. Model 135 or 176.

5, A copy ot the appiopnate

C. SuppIled Accessmes: 176 (Mod&l 1768 Battery Pack

with batteries, Modei 1691 Test Lead Set, 135 (9V
batterv. Model 1691 Test Lead Setl

D, Installed or separate opf~onal accesso~,es. as orderea

Operator’s Manual,

1-14. SPECIFICATIONS

l-1 5. Detailed speclflcations for both instruments are

given on the foilowIng pages

135 DIGITAL MULTIMETER

FIGURE l-l

176 DIGITAL MULTIMETER

FIGURE 1-2

176 SPECS

MODELS 1351176

GENERAL INFORMATION

135 SPECS

l-3

MODELS 135/176

ACCESSORIES

Section 2. Accessories

2-1. GENERAL

This sect,on describes the various accessor,es and
opiio”s avatlable ior use wth Ihe Models 135 and 176.
Some of the followlng accesswe are for use only vath

the Model 135 and some are for use onlvwlth the Model

176~ These accessoi~es w,ll be clearly potnted out as ,o

which instrument they are used wlth~

2-2. MUTUAL ACCESSORIES

The following accessories can be used wrh e,ther rhe
Model 135 or the Model 176.

2-3.

Model 1 SOOA High Voltage Probe

The Mode! 16OOA extends the DMM to 40kV. it has a

1000: 1 d,v,s,on rar,owhich means that 1 volt on the DMM

Corresponds to 1 kV

To Operate: Set the DMM to DCV and 200 Volt range,
Connect the all~garor CLIP on the Model 1600Ato source
Iowa Connecl rhe probe top to so”ice high.
Specifications:Voltge Range: 0 to 40.000 volts DC
Input Reslsrance: 1000 megohms.
Dlvlsion RatlO. 1000 I
Ratto Accuracy~

1000 to 1 +2% terminated in IOMR

2000 to :

2-4.

Model 1651 50 Ampere Shunt

The Model 1651 allows current meawrements to be
made from 0 to 50 amperes DC and from 10 to 50 am­peres AC, It 1s a 0.001 ohm *l% 4.terminal shunt. A fifty
ampere current WI,, correspond to 50 m,ll,volts~

To Operate: Connect separate current leads (not fur­mshed) between the source and the Model 165 1 hex­head bolts. Use leads that are rated

cap.xW Connect thevoltage leads ifurnlshedi between
the Model 1651 screw termmals and the DMM INPUT
terminals. Set the OMM 10 ACV and 2V range or DCV
and 2V range,

+5% terminated I” I Mn

FIGURE 2-1

1600 HIGH VOLTAGE PROBE

UP

10 50 ampere

2-6.

Model 1681 Clip-On Test Lead Set

The Model 1681 contains two leads I 2rr 146
long. lhat are terminated w,th banana piug and sarong­acI10” cltp-on probes.

FIGURE 2-3

CLIP-ON TEST LEADS

2-6.

Model 1682A RF Probe

Model 1682A RF Probe allows voltage measuremenrs
from 1 OOkHz to 250MHz

To

Operate:

Connect the Model 1682A to the DMM input ,acks
Specifications

AC to DC Transfer Accuracy: (7.3X? 5°C) tld6 !rom

1OOkHz to 250MHz at 1V. peak iespondlng. calibrated

i” ims of a slnewave. compat,ble with 1”5lr”ments wiin

1OMR Input res.,srance

Voltage Range: 0.25V to 15V rms

Maw&m Aliowable Input: 50V AC peak. 2OOV (DC+
AC ~eakl
Makmufk Common Mode Voltage. 30V rms. 42 peak
Input Capacitance: 5pF Typical
OperarIng Temperature: 0” to 50°C
Cable Length: 1~5 meters
Accessories Supplied: ENC Adapter. insuiaring TID,
IC Tip. Spring Hook. Carrymg Pouch

Set the DMM to DCV and appropriate range

inches,

FIGURE 2-2

1651 50 AMPERE SHUN1

FIGURE 2-4

1662 RF PROBE

ACCESSORIES ACCESSORIES

MODELS 135/176

2-7. Model 1663 Universal Test

2-7. Model 1663 Universal Test

Two test leads. 1.2m (48 inches) long w,th 12 screw-in Two test leads. 1.2m (48 tnches) long vat,, 12 screw-in

tips. 2 banana plugs. 2 spade lugs. 2 alligator clips wfh tips. 2 banana plugs. 2 spade lugs. 2 alligator clips wfh

boors. 2 needle ups w,th chucks and 4 heavy duty ftp boors. 2 needle ups w,th chucks and 4 heavy duty ftp
plugs.

Plugs

FIGURE 2-5 FIGURE 2-5

1683 TEST LEAD KIT 1683 TEST LEAD KIT

2-S. Model 1686 Clamp-On AC Current Probe

2-S. Model 1686 Clamo-On AC Current Probe

The Model 1665 meawres AC current by clampIng onto The Model 1665 mea?.“& AC current by clampfng onto
a s,ngle conductor. Interrilptmn ot the current path IS a s,ngle conductor. Interrilptmn ot the current path IS
unnecessary, The Model 1665 detects current by sensing unnecessary, The Model 1685 detects current by sensing
the magneuc field produced by the current flow. the magneuc field produced by the current flow.

To

Operate:

Operate:

range. The DMM WI, dtsplay O.lV rms per ampere. range. The DMM WI, dtsplay O.lV rms per ampere.

Set the DMM to ACV and the appropriate To

Set the DMM to ACV and the appropriate

Lead Kit

Lead Kit

FIGURE 2-7

1691 TEST LEAD SET

Z-10. MODEL 135 EXCLUSIVE ACCESSORIES
2-l 1. Model 1304 Soft Carrying Case and Stand.

The Model 1304 IS a soft carrying case and stand (t,lt
baili for Kelthley’s hne of hand held instruments.

The instrument can be secured Inside the case wfth the
thumbscrew (suppledI. if dewed, The thumbscrew IS
also used 10 secure the stand (tilt bail) fo set the ,nsfru­men! upnghf.

1685 CLAMP-ON AC CURRENT PROSE

FIGURE 2-S

2-S. Model 1691 General Purpose Test Lead Set

The Mode, ,691 General Purpose Test Lead Se1 CO”SIS,S
of fwo 0,9 I mm (36 Inches) test leads wirh probe ups
iermlnated I” banana plugs

2-2

FIGURE 2-8

SOFT CASE AND STAND

FIGURE 2-9

1306 DELUXE CASE

2-12. Model 1306 Deluxe Carrying Case.

Model 1306 Deluxe Case is a rugged DMM carwng case
that IS large enough to accommodate the 135 plus var­IOUS other DMM art~cies such as a spare battery. fes,
leads. ew

MODELS 135/176

2-13. Model 1369 Spare Parts Kit

The Model 1359 is a spare parts kit for rhe Model 135
It CO”SISIS of a compIeme”t oi specially seiected spare
pans fhar wlil manta!” several 135 DMM’s for one year
The parts are INsted I” Table 6-2 of Sectlo” 6. Replace­able Parts,

2.14. MODEL 176 EXCLUSIVE ACCESSORIES

2.16. Model 1010 Rack Mounting Kit

The Mode, 1010 Rack Mounting Kit permits the mou”,-

,ng of a single DMM to a standard 5-l 14 in x 19 i” rack

2-16. Model 1017 Rack Mounting Kit.

The Model 1017 Rack Mounting Ktt permits rhe mount­,“g of two DMM’s s,de by sde I” a srandard 5- 1 /4 I” x

19 I” lack.

2-17. Model 1684 Hard Shell Carrying Case

The Mode, 1684 hard she,, carrv~ng case IS a hard wny,
case which is 4 I” v 13 I” Y 14 I” (100mm x 300mm x
350mml~ Ii has a fltfed foam lnserf wth room for 1he
DMM. ~“struct!o” book and small accessories

FIGURE

1766

ACCESSORIES

2-l 1

ELIMINATOR

FIGURE 2-10

HARD CASE

2-18. Model 1766 Battery Eliminator

The Model , 766 Batrerv Ei,m~“ator permits the user to

operate the 176 or 169 from lhne power. The 1766 pro-

vldes the necessary DC voltage to Operate the 176 or

169.

The 1766 firs I” piace of the battery pack (Model

1766) so therefore, precludes the use of the battery pack

(Model 1768). The Model 1766 is capable of working
from a wde range of line voltages such as from 1 OSVAC
to 250VAC to 50HZ or 60HZ.

BAmEAY

BATTERIES

FIGURE 2-12

SAl-rERY PACK

HOLDER

2-20. Model 1769 Spare Parts Kit

The Model 1769 1s a spare parts ii, for ,he MOdeI : 76
it co”sIsts of a compiement of SPeclallY seiecreo space
parts that WIII ma~ntai” several 176 DMM’s lor cne veai
The parts are listeci I” Table 6~3 01 Seci~on 6 Rep!aceaale

Parts,

MODELS 135/l 76

Section 3. Performance Verification

3-1. GENERAL

This secf~on gtves a Performance Verilvzat~on procedure
for both the Model 135 and the Model 176. Each proce­dure wtil be presented separately I” order to avo,d con­fus,on,

3-2 Performance Verlficatlon may be performed upon
recetpt of enher ~nstr~rnenf (1 35 or 1761 10 ensure that
no damage or m,sad,ustmen, has occurred dung trans,,.
Verlficatlon may also be performed whenever there IS
quewcr of elther instrument’s acculacv and foIlowIng
cahbraron. if desired.

PERFORMANCE “ERlFlCATlON

NOTE

3-3. Environmental Conditions For Both Instruments

In order to perform the Performance Verlflcatton the
instr~men, to be venfied m”st be between 1 B’C to 2B’C
at less than 80% R.H.

3-4. Recommended Test Equipment

Recommended test equipment for performance verlfl­cat,on of both instruments IS hsted in Table 3- 1 Alternate
test equipment may be used. However. 11 the accuracy IS
not at least 3 ttmes better than the instruments speclfl­camns. addlnonal allowance mwt be made m the read­I”@ obtalned.

RECOMMENDED TEST EQUIPMEN

TABLE 3-1

ITEM DESCRIPTION

A DC Calibrator 1v. 1ov. 1oov. 1ooov
B AC Calibrator 1v. IOV. IOOV

High Voltage Amplifier

C

(Used wth Model 745Ai *0.04%

D Decade Resistor 1K. 10K. IOOK. 1000K. 10M
E Cuirenf Calibrator 1 mA. I OmA. 1 OOmA. 1 OOOmA.

i-0.002%
+0.022%

1 ooov

+.02%

10A

+.03% DCA. +.05% ACA

WARNING

All service information is intended for qualt­fied electronic maintenance personnel only.

WARNING
Some procedures require the use of high volt­age. Take care to prevmt contact wth lwe
circuits which could cause electrical shock

resulting in injury or death.

CAUTION

SPECIFICATION

3-1

PERFORMANCE VERIFICATION

3.6. MODEL 135 PERFORMANCE VERIFICATION
3-7. DC Volts Verification

A Select ihe WV funann.
B. Connect the DC Calibrator ,ltem A. Table 3-I) to the

135

C~ Follow Table 3-2 and apply the required DC Voltage

D, Repeat all checks with nega1,v.s voltage

V-R and COM fermnals. Refer to Figure 3- 1

fo, each range, “er~fy rhat each reading IS WI,,,,” spec­iltcatlons iwed tn Table 3-2.

MODELS 1351176

DC VOLTAGE PERFORMANCE CHECK

TABLE 3-2

Range Applied

Voltage

Allowable Reading

at 18’C to 28°C

FIGURE 3-l

135 DC VOLTS VERIFICATION

3-6. AC Volts Verification

A~ Select the ACV functmn.
B. Connecr the AC calibrator (Item 8. Table 3-l) to the

135 V-Rand COM termlnais. Refer fo Figure 3-2,

C, Follow Table 3-3 and ~DDIY the reaulred AC Voltaae

for each range. Venfy th’ai <he reading IS wlfhtn speci­ftca11ons Wed I” Table 3-3.

135 AC VOLTS VERIFICATION

FIGURE 3-2

746A

P

FIGURE 3-3

135 HI VOLTAGE ACV VERIFICATION

3-9. Resistance Verification

A. Select the OHMS funcrlon
By Conneci rhe Decade Resistor (Item 0. Table 3- 1) tothe

135 V-s2 and COM terrmnals. Refer 10 Flgure 3-4,

C. Follow Table 3-4 and apply the

for each range. Vertfythat each read,ng isw,th,n soec­lficatrons Ifsted in Table 3-4

requfred ressstance

AC VOLTAGE PERFORMANCE CHECK

TABLE 3-3

Range

Applied Voltage

l,OOOOVat 10KHz
I O.OOOVat 500Hz

2oov 100OOVat120Hz

Allowable Reading

at 18°C to 28’C

~9885 to LO1 15
9,885to 10,115

98.85to 101,15

I

FIGURE 3-4

135 RESISTANCE VERIFICATION

MODELS 135/l 76

PERFORMANCE VERIFICATION

TABLE 3-4

Allowable Reading

at 1wc to 28Y

9970 to 1,003o

9.978 to 10.022

99.78 to 100.22

997.8 to 1002.2

3.898 to 10.102

i

RESISTANCE PERFORMANCE CHECK

Range

2KR

ZOKR

200Kfl

2000KR

20MR

3-10. DC Amps Verification

A, Select the DC Amps function.

B. Connect the DC Calibrator ,l,em A. Table 3- 11 10 the

tnput of the Current Calibrator (Item E. Table 3-l I
Connect the OU,,,U, of ,he Current Calibrator to the

135’s mA and COM terminals. Refer 10 Figure 3-5.

C. Select the 20mA range and apply a 10,OOmA curren,

to the 135. Ver,fv that the reading IS with,” 9,93 to

10.07.

D. Select the 1 OA range and connect the outp”, of the

Current Calibrator 10 the 135’s 10A Hi and 10A LO
terminals Refer to Figure 3-6

E. Apply lO.OOA to the 135 and ver,fy tha, rhe reading

IS w,,h,” 3.88 to 10.12,

3-11. AC Amps Verification

A~ Select the AC Amps functlon and the 20mA range.

8. Connect the AC Calibrator (Item B. Table 3-l) to the
mput of the Current Calibraror (Item E. Table 3-11
Connect the output of the Current Callbrafor to the

135’s mA and COM term~nais. Refer 10 Figure 3-7

C~ Apply a 10,OO mA currenr a, 500H2 and verliy lhal

the readfng IS w,th,n 9~80 to 10.20~

D. Select the 10A range and connect fhe outp”, of the

Curren, Calibrator fo the 135’s 10A HI and 1 OA LO

terminals. Refer fo Figure 3-8.

E. Apply a 1 O.OOA current at 500Hz and ver,fv that fhe

readang IS wfhin 9.80 10 10.20.

343A

FIGURE 3-6

135 1OA DC AMPS VERIFICATION

FIGURE 3-7

135 AC AMPS VERfFlCATlON

343A

FIGURE 3-5

135 DC AMPS VERIFICATION

135 ,OA AC AMPS VERIFICATION

FIGURE 3-8

PERFORMANCE VERIFICATION

3-12. MODEL 176 PERFORMANCE VERlFlCATlON

3-l 3. DC Volts Verification

A. Select the OC Volts functuon.

6. Connect the DC Calibrator IItem A. Table 3-l) to the
176’s HI and LO ~npu, ierminals. Refer to Fig’ure 3.9.

C. Follow Table 3-5 and apply the required DC Voltage

for each range, Verify tha, each readtng IS wtfhin spec­ifications Ifsted I” Table 3-5.

D. Repeat all checks wtth negatwe voltage,

MODELS 135/l 76

FIGURE 3-10

176 AC VOLTS VERIFICATION

Applied

Voltage

TABLE 3-5

Allowable Reading

at 18°C to 28°C

DC VOLTAGE PERFORMANCE VERIFICATION

Range

4’ 1

I

FIGURE 3-9

I76 DC VOLTS VERIFICATION

3- 14. AC Voltage Verification

A. Select rhe AC Volts funcuon.

By Connect the AC Calibrator and HVAmpllfier iltems B

and C. Table 3-l) to the 176’s HI and LO terminals.
Refer to Figures 3-10 and 3-1 1.

C. Follow Table 3-6 and apply the required AC Voltage

for each range. Verlfythafeach reading iswithIn spec-

lflcatlons listed ,n Table 3-6.

I J

178 HIGH VOLTAGE ACV VERIFICATION

3-15. Resistance Verification

A, Select the OHMS funcnon.
8 Connect the Decade Re%$,or (hem 0. Table 3-I) to the

176 HI and LO ~npu, terminals. Refer to Figure 3.12.

C, Follow Table 3-7 and apply the reqwred resistance for

each ranae. Verlfv that each readina is within soeclfl-

cations ll;ted in fable 3.7~

RESISTANCE VERIFICATION

Range

FIGURE 3-l 1

TABLE 3-7

Applied

Resistance

Allowable Reading

at 18’C to 28’C

1

I

AC VOLTAGE PERFORMANCE CHECK

Range

;:: 1 1 ~OOOOVa, OOOOV at 1 OKHz 1 KHz

2% 1 1 ,OOOOVat O~OOOV at 20KHz 1 KHZ
2ov lO.OOOVat 1OKHz
2ov 10,OOOVar 20KHz

2oov 100 OOV a, 1 KHz

1 ooov 1OOOOVal IKHz

3-4

Applied Voltage

TABLE 3-6

Allowable Reading

at 18°C to 28°C

.9885 ,9885 to to 1.01 1.01 15 15

9,885 9485 to to X0515 10,115

9.885 to 10.1 15

9.485 to 10.515

98.85 10 101,15

988.5 to 101 1 5

176 RESISTANCE VERIFICATION

FIGURE 3-l 2

MODELS 135/176

PERFORMANCE VERIFICATION

3-16. DC Amps Verification

A. Select the DC Amps tunctton.

8. Connect the DC Calsbrator (Item A. Table 3-l I to the
,nputottheCurrentCai,bra,~r ,ltemE.Table 3-11, Con­necf the output 01 the Current Calibraror to the 176 HI
and LO l”p”r terminals. Refer to Figure 3- 13.

C, Follow Table 3-8 and applv the required c”rrenf for

each ranges Verliy ihat each reading IS wrhln spew
flcatlons ilsted I” Table 3-8,.

TABLE 3-6

DC AMPS VERIFICATION

Range

2mA 1~OOOmA ~993 IO 1~007 2mA 1 .OOOmA at 1 KHz 980 to 1320

20mA 1 O~OOmA 9.93 10 10.07 20mA I O.OOmA ar 1 KHz 9~80 10 IO 20

200mA 100 OmA 99.3 to loo,7 20OmA 100,OmA at 1 KHz 9aoto 1023

2000mA 1000 rnA 993 to 1007 2000mA lOOO,mA at IKHz 980 10 1020

343A

Applied
CtlrrWlt

Allowable Reading

at 16°C to 26°C

3-17. AC Amps Verification

A.

Select the !iC Amps funwon

B.

Connect the AC Callbraror jlrem 6. Table 3-1, to the
~“puiotIheCurrentCaiibrator,ltemE,Tab,e3-ti Con­nect the
and LO termnals Refer to F,gure 3-14

C,

Foliow Table 3-9 and apply the required curient for
each range. Vertiy that each reading 1s
cations ksted in Table 3-9

Range

I I

Outpu!

of the Current Callbraior IO the 1 76 Hi

TABLE 3-9

AC AMPS VERIFICATION

Applied Current

Allowable Reading

a* 19°C to 26°C

I

warhtn spew,-

176 DC AMPS VERIFICATION

FIGURE 3-13

176 AC AMPS VERIFICATION

FIGURE 3.14

3-5

MODELS 135/l 76

THEORY OF OPERATION

Section

4. Theory of Operation

4-l. GENERAL

Th,s sect,on contatns the c,rc”~, descrtpflons for The
Model 135 and Model 1 76. The iollowng dlscusslons of
c,rcu,t theory veil be separated <“to 2 maw sect\ons~ The
2 map, SeCtIOnS are:

I ) Model 135 Circuu Theory

21 Model 176 Czrcutt Theory

The ~nfprmat,on contaned I” each of these 5ectto”s IS

arranged I” the following manner.

1, Overall Functional Description

7.1 Stgnal Condittonrig

3) A/D Converter

4) Display
51 Power SUPPlY

To facilnate understandtng. each descrtptton IS accom-

panted wth slmpilfied schematIcs. blockdlagrams. tables

and graphs. Detacled st~emaiics of ,he Moaei 135 a”~

Model 176 are orovlded ,n Sewon 6

4-2. MODEL 136 OVERALL FUNCTIONAL

DESCRIPTION

The Mode, 135 1s a 4-1 i2 aqr. t20.000 co”“, hard
held DMM It has 4 DC voltage ranges. 4 AC voltage
ranoes. 5 res,srance ra”aes. 2 DC C”rre”l ranoes ant 2

The 135 was destgned for h#gh periormance ar zov? cosi

To meet these design goals the 135 takes advantage r,’
standard <off the shelf” components, The A/D c~)“vertel

was designed from scratch using dlscrete componenls for

lower power ‘onsumpt\on and ,mproved aeriorman:e
over prssen,ly available LSI A/D converters

Ftgure 4- 1 shops the overa,, bioce diagram 1-r xw mc^ei

135

V-Q

IAC CONVERTER ONLY)

ATTENUATOR

RESISTANCE

+e.4v

-5V ANALOG
+5V ANALOG
+5V DIGITAL

ANALOG

FIGURE 4.1

135 BLOCK DIAGRAM

THEORY OF OPERATION

MODELS 135/l 76

4-3. Signal Conditioning

The Signal Condltlonlng for the Model 135 includes DC

arten~atmn iexcept on the 2 Volt range,. AC attenuation.

AC/DC conveis~an. Ohms conversion and current

ShUrxS.

A. DCV Signal Condittonlng consists of one lOMnpas-

swe dwder~ The taps tram this divider are inputted
dlrecrly to rhe A/D converter through the rotary range
watch S102. Table 4-1 state~~he associated attenua­tton with each range, Potentiometer Rl 13 trims the
ga,n for the 20 Volt range. The overload protection
IS provided by the llmmng resistor Rl 15.

ACV

‘75OV range for ACV

B. ACV SIgnal Condmonmg consists of a 1 OMR pasSwe

dwlder. AC buffer amplifier and AC co”verWr. The
scalmg IS accompi~shed by the same 10MSIwsswe
dlwder that IS used for DCV scaling, After the divider
rhe :,gna, IS AC coupled ,nto U105 the AC Buffer

Ampl~flei. The slgnai is then applied 10 the averaging

piec~~~on rectlfler U 104, It IS driven at low lmpedan.ce

by the AC coupled buffer U104 performs the AC con­version, It then passes through a two stage low pass
filter which converts it to DC. This OC level IS applied

fo the A/D converter. Input resistance for the AC con­verter is 1 OfvUlshunrea by less than 100 pf.

TABLE 4-1

AND DCyA7TENUATlON

Rl 1 1 establishes AC zero while R 109 determ,nes the
full scale gain (19000 counts), R105 and C 108 pro­vlde the low pas5 f,lter ro average the half wave recw
fled outputs Overload protection IS prowded by d,odes
CR104 ahd CR105 and currentllmttlngreslstorR1 10.
Figure 4-2 shows a simplified SchematIc of the AC
cOn”erter.

C

Resistance Signal Condltloning 1s accomplished iax­metrically. That IS. a precision reference resistor and

Rx are put in ser,es wth a 2,5 volt reference, There­fore. the current developed i” the two ~BSIS~IIS 15 the
same. Taking the ratlo of rhe voltage drop across Rx 10
the drop across R<e,e,en<e coriectly caiculates ohms.
The value of the voltage reference IS irrelevant. as ,t
only serves to apply a source of currentto the ies,stors
(Rx and Rrc~ewncel. The preceding theory IS illustrated
mathematically in the following equations. Refer to
Figure 4-3,

I =

Vdisplay = ;;;f;,:;;;f$ X 10,000

Vdisplay =

Vdisp’av = , [Rref + Rp C Rx. Rp. Rx]

Vdisplay = & X 10.000 = & X 10.000

Vref

Rref + Rp + Rx

lL~ref+flp+R~]-i[~p+~xJ x’o.ooo

I [Rx1 -0

IRX

x 10.000

lOMR DIVIDER

v2v

!

4-2

90KR

1 OKR

2ov f---l*

2oov

750v

AC

COUPLING

SIMPLIFIED

BUFFER

UlO!i

- RECTIFIER - LOW PASS -

PRECISION

u104

FIGURE 4-2

AC CONVERTER BLOCK DIAGRAM

TWO STAGE

FILTER

R105

7

Cl08

MODELS 135/176

THEORY OF OPERATION

The prectsion reference resistors are wallable from
the DC divider. Ap and Cl204 form the overload pro­te~llon for the Ref LO ,“put “ref is approxnnately 2.5
volts and is provided by pass rrans~stor QlOl, 0204
conducts much like a zener diode at approxlmafely

9 volrs to absorb the imtial overload as Rp heats up.
16 res,stance goes from 1 K to several megohms effec-

ttvely limttrig cuireni.

h--- Lo

FIGURE 4-3

SIMPLIFIED OHMS SCHEMATIC

CAUTION

Do not exceed maxtmu” allowable input

Instrument

IS unfused.

4-4.

A/D

The A/D converter IS really the heart of lhe znstrumer,
If 6 engmeered from dlscrere SSI CMOS and low
analog circuitry The operation of rhea/D converter 1s of
the dual slope pr,nc,ple. The tuning of rhe dual siope
measurement IS dwded into 3 pertods: Auto Zero, Sgnai
Integrate and Reference Integrate. The fo,low,ng fhree

SIeps lll”Strate the three measurement pertods

1, Auto Zero

The Auto Zero per,od is 100 rnsec in !engt* v11tzr

corresponds 10 10.000 clock pulses Dw?g :n,s
period the reference voltage IS stored on caoacilc:
C205~ Capacllor C206 stores +vos:-v~s2 Refer tc
Figure 4-5

Vref

damage may occur, 10A range

Converter

powe,

BUFFER

INTEGRATOR

D AC/DC Current measuremenrs have two ranges: the

20mA range and the 1 OA range. These two ranges are
3-l/2 d,g,t readings in order to keep, the burden volt­age under 250mV, The 20mA range IS protected by
d,odes CR1 08. CR1 09 and Fuse Fl 01. The cuirent
shunt for the 10A range IS destgned to m,n,mize
~ntetnal heatlng I” the event of overloads Figure 4-4
is a simple block diagram showing AC/DC current
measurements~

FIGURE 4-4

BLOCK DIAGRAM FOR CURRENT MEASUREMENT

FIGURE 4-5

AUTO ZERO

DISPLAY

THEORY OF OPERATION

MODELS 135/l 76

21 Signal Integrate

As wtth the Auto Zero phase the Signal Integrate
phaseisof lOOmsecdurat~on.The~nputafrheA/O
converter is first buffered by one half of U2 13 and
lhen the signal 1s integrated by the other half of
U213. When pOSitlveSignaiSareapplledtotheA./D
the ~nregrator generates a negawe go’ng ramp.
Thus can be seen al the output of the lntegraror ip~n

1). When negative signals are applied IO the A/D

the mregrator generates a powwe going ramp.

The level of the mtegrated signal at the end of this

permd islgnal integrate) is proportional to the

average of the appiled s!gnal during th!s pewd.

Since Signal Integration is a constant 100 “sec.
the converter exhibits high rejectron at 50Hz and
60Hz. Refer to Ftgure 4-6 for a slmpilfled dtagram
of Signal Integrate.

SIGNAL INTEGRATE (IOK COUNTS1

FIGURE 4-6

SIGNAL INTEGRATE

3’1 Reference Integrate

The Reference Integrate pernd for a full scale8nput

120.000 counts) is 200 “sec. During this period
the fntegrator is returned 10 a baselrne level by
applying a reference voltage of a polaray opposne

to that of the slgnal. This IS accomplished by
grounding the appropriate side of the reference
capacator~ The dtgltal output IS generated from the

latches wlthtn UlOl which store the number of
clock pulses required for the lntegraror to return
to baselme levels.
For inputs le?,s than full scale ifull scale = 20.000
countsI. the A/D automatically reverts to Auto
Zero. This happens I” the rime period of the 200
msecs remafmng after the return to baselme level.

Refer to Figures 4-7 and 4-8 for a slmplifled dia­gram of Reference integrate.

NEGATIVE REFERENCE
INTEGRATE (20K COUNTS AT FULL SCALE)

NEGATIVE

INPUTS TO A/D

POSITIVE REFERENCE INTEGRATE

(ZOKCOUNTSAT FULL SCALE)

INPUTS
TO A/D

POSITIVE REFERENCE INTEGRATE

Also Included rn the A/D are 2 adjustment poten­t~ometets. R205 is part of a translation network
which Insures rhat the comparator ourplit during
autozero IS at or near the threshold of U204C.
which is ihe zero crosstng flip flop. Therefore thus
adlustment controls symmetry between posmve
and negative jnputs Shorting C204 (as I” the cal
procedure) and adjusttng A205 for a reading of
~0000 accomplishes this symmetry adjustment.
The A/D gal” control (R102) IS rhe other adlust­men,. This potentiometer controls the %ference
voltage and compensates for all gain errors wlthfn
the dual slope A/D converter,
The A/D is rat~omerr~c. with dlfferenrlai reference
fnputs~ Therefore

Vd6play =

The full scale inputs for the A/D are as follows:

ACV.DCV.fi.DCA.ACA = +2V (full scale input)

4-5.

Input &dfer

The analog watches used for the A/D converter are
CMOS (U210. U2 1 1. U2 121. A low drift. low bias cur­rent buffer iU2 141 precedes the A/D input. The offsel for
thfs amplifier iU2 141 1s nulled w(Ih potentiometer R207.

4-6.

Reference Voltage

The reference voltage (Vwl IS provided by a dlwder net­work placed acnxs a temperature compensated zener

(CR1 101. One half of U 102 prowdes the zener wrh a self
regulamg bias, The reference voltage IS approx~marely

1.0 volts and can be fmely adjusted by R102.

FIGURE 4-8

(Ref ;‘““;if Lo) x 10.000

4-4

NEGATIVE REFERENCE INTEGRATE

FIGURE 4-7

4-7. Display

The 4-l/2 digIt Llquld Crystal Dlspiav IS driven by LSI
counter/driver U 10 1~ The Backplane and the segments
of the dtglts are driven dlrecrly by UlOl The zebra strip
connector transfers rhe dwe slgnais from the P-C board
Onto the LCD~

A low battery mdlcator is detected and actuated by one
half of U102. Thts an”““c~atcx. the minus srgn. and a,,

MODELS 135/176

declmal pants are dwen by the exclusive OR gate arrays

U201 and U202.
The dtgmzed measuremen, data IS presented by out-

Put ifnes IO

wave having the same ampiltude and ‘reauency as rhe
Backplane l,“e. When rhe ii”e5 IO the d,splay segmenrs

are driven 180” our of phase with the Backplane the seg­ments are ON. Conversely. when tn phase the segments
are OFF The dectmai points and rhe LO battery #ndlcaror
are Turned OFF and ON s,m,larly.

4-8.

The prec,s~on reference current source “102A also dou-

bles as the +5 volt supply. P,n 1 of U 102 IS the V+ supply

The 5 volt supply IS generated by a power ~““erter c~rcui,
(U1031. This device charaes capacitor C 102 and then

rwerses it. Thts effect,“& gene;ates -5 “pits. A “oi&,ge

doubler c$rc”tt consisting of C.103. C104. CR101 and
CR102 generates +8.4 KITS. Th,s voltage IS only used
on U104 which is the precision recttfler amplifier iUlO4)
of the AC co”“erter.

rhe LCD, These lines are dwen by a square

Power Supply

4-9. MODEL 176 OVERALL FUNCTIONAL

DESCRIPTION

The Model I 76 IS a 4. I /2 diglf. f20.000 count portable
bench DMM It has 4 DC “&age ranges. 4 AC “oirage
ranges. 5 ie~iSta”ce ranges. 4 DC current ranges and 4

4C current ranges. Along w,th theselunct,onsand ranges

tt has 100i.1VDC and AC “offs senstttvlty with 100mQ
res~siance se”~m”~ty The DC and AC current senstt>“,,”
IS 1uA.

The 176 was destgned for h,gh performance at tow cosr
To meet these design goals the 176 lakes advantage 01
standard “off rhe shelf” components. passive s~g”aI con­dltionlng and multlfuncrion components and CI~CUIIS,
The A/D converter was designed from scratch us,ng
dlscrere SSI CMOS c~mppnent~forlowpowerconsump­r!on and improved performance-aver presently available
LSI A/D converters.

THEORY OF OPERATION

2V ‘1

2ov

TABLE 4-2

Attenua~,on Factor

i’ 0

+i so

ACV AND DCV ATTENUATION

Rang.?

2oov

I ooov ?lOOO

OHMS

REFERENCE

VOLTAGE

/

ATTENUATOR

RI

.d

I I

IAC CONVERTER ONLYY)

+8,4V

FIGURE 4-9

176 BLOCK DIAGRAM

A/D

CONVERTER

OlSPL4Y

ANNUNCIATOR

DRIVERS

-5V
+5V DIGITAL
+?JV ANALOG

DIGITAL

J-5

THEORY OF OPERATION

ZVRANGE R103

MODELS 135/176

R106

8.9775MQ

R108

gaoK~ _“_. .,, ..--

R108
90KR

R108
9KR

A108
1KR

4-12.

AC Volts

The AC Volts Signal Cond,!,on,ng cons,s~s of a passive
d,v,derfR109-Rl 11.Ri 14andC103~C106)andfheAC
converter During AC “okage measurements the meas­ured sqnal IS aopl,ed 10 ihe dlwder and IS atten”aIed by

1,10.l00or1000forthe2V.20V.200orlOOOVrange

respectively, The capacitors (C 103 C 1061 are used for
~orni)e”salion for stray capacitance and for frequency
characrer,st~cs of rhe resisrors, There IS no capaaror used
on rhe 2V range for frequency compensation There are
onlytwocapacitors ,nrhecircu,tforanyotherrange~Th,s
reduces ,nteract,on between ranges and allows easy ISO-

lhon of taulrv capacitors~ The outputfrom the AC dlvtder
IS appl,ed to rhe AC converter where 8, IS recflfled and
scaled before being appI,ed to the A/D converter, Refer
to Figure 4-l 1

2OV RANGE

-

ilO
1OOOVRANGE

DCV SIGNAL CONDITIONING

FIGURE 4-10

1-2 VOLTS TO +2

VOLTS)

.-’ +, _ , ~107 R116

_. - _

R109
lKS2

The AC converter IS a preclson half wave reci~f~er with
high mpedance fnput and sufflclenr gal” 10 produce a
DC output equal to the ims value of a sine wave input
Following the sIgnal path. C 107 1s used as a DC blocking
capac~ror so thar DC oftsets ,n rhe measured signal do no1
affect fhe readmg. UlO8 IS a unify gain buiier used lo
eliminate loading 01 the AC dlwder and prwde Iow im.
pedance dwe for rhe acfual AC converter ” 109 Capa,­tom C 109 and Cl 10 eliminate any problem due to the

offset voltage of U 108~ Rl 19 R 12 1 ad,us, the gal” of
the AC converter required to convert from fhe rect$hed
waveform average 10 rms equ~“aIeni, Resistors RI ! 7 and

4 1 18 adlusr 0~1 any error at zero due ro oifsers I” ” 109

U 109 uses feed forward compensation provided by C 1 14
and will become unsiable when any capac~riue load isuch
as a scope probe) IS attached near rhe ou1pu1 cjrcuitry 01
the CIP amp lU109)~ Refer 10 Figure 4.12

ilooo

FIGURE 4-11

AC VOLTS DIVIDER

d-&,%-TO AC CONVERTER

>E

J. --_ lOOKa PROTECTION

OPEN. C103. C104. Cl05
DEPENDING ON RANGE

4-6

R120 I-DCD’J’

AC Cal

CR107

Al 19

R118 50KR
ZERO AD.!

FIGURE 4-12

AC CONVERTER

MODELS 135/l 76

THEORY OF OPERATION

+--REF LO

tars RI 07a;d R 108 are a150 the DC” dtvider, Us,ng the

1KR. 10KQ. 100KR. IOOOKn and 10MQ tapson

the dwder for ihe 2K.Q. 20Kn. ZOOKR. 2000Kfi and

20MR ran4e5,ihedls~lavedreadlnaistheac1ualres,si-

II

RX

Input HI Input LO

Ret HI Ref Lo

OHMS SIGNAL CONDITIONING SIMPLIFIED

PROTECTION

INPVT HI

UNKNOWN
RESISTOR

h

FIGURE 4-14

INPUT LO

6

PROTECTION

INPUT>

h

FIGURE 4-13

OHMS SIGNAL CONDITIONING

PROTECTION

lOKI2

4iOKn

PROTECTION

TO A/D INPUT 6”FFtR

OR AC CONVERTEP

lNP”T

“,.‘,:“, T

R106

0 1R

INPUT--------/i

FIGURE 4-l 5

AMPS SlGNAL CONDITIONING

THEORY OF OPERATION

4-15. Input Buffer

FOLDOVER PROTEC-

TION RESISTOR ON

UllO

FIGURE 4-16

INPUT BUFFER

4-16.

A/O

The 176 A/D converter is essent~allv the heart of the

instrument. It has been engineered wrh discrete SSI
CMOS and Ibw power analog c~rcu,fry. This A/D con-

Convener

BOTTOM SIDE OF PCB
ON REV C PCE’S.

C1’18

O.lpF

MODELS 135/176

The Auto Zero period IS 100 msec I” length whtch
corresponds to 10.000 clock pukes. Dur,ng th\s
perlod the releience voltage IS stored on capacitor
c 1 1 7. capac,ror c 120 stores +Vasl “os2. Refer to
Figure 4-1 7.

21 stgm Integrate

As wth the Auto Zero phase the SIgnal integrare
phase 1s of 100 msec duralton. The input of the A/D
converter IS f,rst buffered by Ul 10 and then II IS
integrate0 by Ul 11, When posmve s,g”als are
applied to the A/D the ,nfegrator generares a nega­we gang ramp. This can be seen ar the output 01
the !ntegrator (pin 11~ When negative signals are
applted to the A/D rhe integrator generates a pas,­we go,ng ramp.
The ieve, of rhe integrated signal at me end of fhls
period tslgnal lntegratei IS proportional to the aver­age Of the applied s,g”al dur>“g ,h,s pert& S,“ce
SIgnal Integrate IS a constant 100 msec. the A/D
co”“e~ter exh,b,ts h,gh re,ect,o” at 50Hz and 60Hz,
Refer 10 Ftgure 4-l 7.

3) Reierence lnteglate
The Reference Integrate perlod for a full scale ,nput
(20.000 co”nls, IS 200 msec, During rh,s period the

INTEGRATOR

Cl19

COMPARATOR
ITAANSISTORS
010,. 102. 103,

4-8

RE! LO

FIGURE 4.17

A/D CONVERTER

MODELS 135/l 76

,ntegraror IS returned to a basei,ne level by appiylng
a reference voltage 01 a p&my oppos~re to that of
the SIgnal. This IS acompllshed by grounding the
appropriate side of the reference capacjtor The
d,g,,al output 1s generared from rhe latches wlthln
“107 which store rhe number of clock pulses
requmd for the integrator to r.?t”rn to basellne
levels
For ,np”ts Iess than tuil scale ifull scale = 20.000
coun,sl. rheA/D automat~caliy reverts ,oAufo Zero.

This happens in fhe fime perNod of the 200 msec
rema,n,“g after rhe return to baSelIne level
AIs, Included I,. the A/D are 2 ad,ustmeni pore”-

tiometers ‘8125 IS part ot a translation network

which insures that the comparator output dung
Auto Zero is at or near the threshold of VI 14C.
wh,ch IS the zero crossjng fltp flop, Therefore thts
ad,usrment conrrois symmetry between posweand
negmve ~ny)uts~ Shorting C 1 18 jas I” the Cal Proce­dure, and adlusting Rl 25 for a read,ng of 0000
accomplishes this symmetry adjustment,
The A/D gan conrio (RI301 IS the other adjust-

ment. Th,s potentiometer controls the reference

voltage and compensares for all gal” errors wtlhln
fhe d”ai slope A/D co”“er,er~
The A,D conver,er is rat~ometrlc wfh d~fferenrial
reference inputs, Therefore

THEORY OF OPERATION

0, Amps LC or DC

In reference IO Flgure 4- 15 CR101 pro,ects tne .ow

Vdtsplay = (Ref ,yil”u,‘,, Lo)

The full scale ,nputs for the A/D are as follows:

1. ACV = +2V (full scale mput)

2. DCV = ezv IfUll Scale inDuti

3. n = t2v (full Scale l&Ii
4, ACA = +~2V lfuli scalB InPut)

5. DCA = +.2V (full Scale InPUtI

x 10.000

4-l 7. Protection Circuitry

A,

DC volts

In reierence to Ftgure 4- 10. RI 03 protects the ~“stru­menr from damage by llmitlng the current IO the tnput

buffer to about 2mA max~m”m, Extended
of greater than 300 volts on the 2VDC range may
damaae Rl 16.

B

AC V&s

in reference to Figure 4-l 1, Rl 16 protects the ~nstru-

ment from damage by l,m,,,ng rhe curren, to ihe AC
converter to
appl,cat,on of greater than 300 volts on the 2V AC
range may damage R 103~

C,

Ohms
In reference to Figure 4-13. there are three CO”PO­nents that protect Ihe ~nstrumenf in the eve”, voltage
1s appited lo rhe mput whtle on the Ohms lunct~on
TheseCompo”entsareR103. RTIOI andQ104, R103
works exacflyitke ildoesforDCvo,tagemeas”reme”,s
by limnng current $mo the tnpui buffer amplIfter
Q104 1s used as a tow leakage zener with a break­down voltage of app,oxtmately 10 “olts~ RTl 01 1s a
positive temperature coeff~ctenf thermistor, RTI 0 1
I,m,ts the curie”, gofng 10 Q104 by increasing its
res,stance greatly when heated Thus happens when
volrage above 10 volts IS applvzd to the tnput When
vdfages of much greater value than 300 volts are

approximately

1 OmA maximum. Extended

a~pl~catlOn

THEORY OF OPERATION

MODELS 135/l 76

power converter which generales -5 volts by chargmg
Cl27 with the +5V supply, then switchtng the pos111vB
lead of C 127 to ground and charyng C 130 to -5 vOltS~

CR108. CR109. Cl24 and Cl26 form a simple voltage

doubler drwen b” Cl 27 The result of the doubler equals
+8~4 volts wh,ch is used exclusively by U109 I” the AC
COnYerter.
The +5 volt supply IS spltr ,nto two separate lhnes, One

for the analog c,rcu,try and one lor the diglial ctrcutrry
The -5 volt suppiy IS used for rhe comparator. the analog
swtches and mosr of the OP amps.

The facr that CR1 I 1 IS stable wfh r,me and temperarure
enables it to also be used to deilve the prec,se 1 0000
volt and 0.1000 volt reference signals rhat are used for

Volts and Amps. respectively, Durmg voltage measure-

ments the CR 1 1 I voltage IS attenuated to 1~0000 volts
by Rl 13. Rl 15 and R130~ The 1 ~OOOOV s,gnai IS fed
to the A/D reierence ,nput~ During the Amps funcnon
fll 15 IS replaced by a secr~on 01 RlOB. Th,s atfenuares
the 1,OOOOV to 0,lOOOV wh,ch 1s a&led ,o thk A/D
reference (“put,

MODELS 135/l 76

MAINTENANCE

Section 5. Maintenance (Troubleshooting, Calibration)

5-l. GENERAL

Model 135

Model 135
Model 135
Model 176
Model 176

Model 176
Model 1766 Troubleshooting

Caltbrat~on

TroubIeshoor<“g

Batrery Replacement. Fuse Replacement

Cai,brar,on

Troubleshooting

Battery Replacement. Fuse Repiacemenr

5-2. MODEL 135 CALIBRATION

The Model 135 recommended cal,bratlon equ,pmen, IS
!~sted I” Table 5-l Alternare equipment may be usea
However. the atc~rac” of rhe alternate equipment must
be ar ieast 3 limes bertei ihan the Model 135’s spec,f,-

cat,ons or equal to Table 5- 1 spec,f,catlons~

5-3. Environmental Conditions

Callbratlon shoula be peiformed under laboratorycondl­W,“S having a” amble”, temperature of 23°C _+I ‘C and a
reiat,ve humld,ty 01 iess than 70%, If the instrument has
been sublected to temperaiures outside of this range. or

to h,gher hurmd,,“, aI,ow one hour mln~mum for Ihe

tnsrrument to stabtlize at the speclf,ed e”v,ronme”tal

cond,,,ons before beglnnlng the callbratlon procedure.

5-4. Calibration Procedure

NOTE

Cahbratlon should be performed bYqualifIed
personnel “sing acC”rate and reliable eq”,p­ment.

CAUTION

Do nor exceed the max,mum allowable input
voltage. Instrument damage maY occur. Max­mum allowable inpuTs are stated I” the spec-

ficatlon.

RECOMMENDED CALIBRATION EQUIPMENT

) ITEM 1 DESCRIPTION

ITEM DESCRIPTION

A A
8 8 AC Calibrator AC Calibrator

DC CaI,brator DC CaI,brator

TABLE 5-1

SPECIFICATION

I

SPECIFICATION

:ov 1oov. 1ooov :ov 1oov. 1ooov

+ 002% + 002%

I”. iv. 1ov. IOOV I”. iv. 1ov. IOOV

?022% ?022%

SOLDER SIDE OF A/D BOARD

FIGURE 5-1

1 MFR, \ MODEL )

MFR,

Fl”klZ Fl”klZ

H-P H-P

MODEL

343A 343A

745A 745A

MAINTENANCE

MODELS 1351176

Remove the short from C204 Select the 2V range and
short the !nput termtnals (VR to COMI, Adjust R207
for ~0000.

Remove the short from the input terminals Wlto
COM)~ Apply + 1.9000VDC to VRand COM and adjust

R102 for +1.9000.

Select the 20V range and apply + 19.000VDC to V-n

and COM and adjust R1 13 for + 19.000.

Select the ACV funcflon and the 750V range. Short
the (“put term,nals (V-R to COM) and adfust Rl 11
for 000.0,

Select the 2V range. Apply 1.9000VAC at 500 Hz to
V-fl and COM and adfust RlOS for 1.9000.

R207

R205

I I

R102

Model 135 and provtde instruction on how to avold
damaging them when they must be removed or replaced.
A. Static sens~we dewces:

Reference Des,gnar,on Keithlev Part Number

0. The above Integrated clrcults should be handled and
transported only in protection contamers. Typically
they will be received I” anti-static tubes or elecrr~callv
conductive foam. Keep the devices in thefr origlnaf
containers until ready for use.

C. Remove the devices from their protectfve containers

only at a properly grounded work bench or table. and
of~lv after grounding yourself by using a wrest strap.

D. Handle the devices only by the body. Do not touch the

Pll7S.

E. Any pnnted c,rcu,l board (“to which a de”,ee IS to be

inserted must also be grounded to the bench or table.
F~ Use only ant,-stat,c type solder suckers.
G. Use only grounded t!p soldering irons.
H. After soldering the dewce ,“to the board. or properly

lnsertlng it 1nt0 the matmg receptacle, the devlce is

adequately protected and normal handlmg can be

resumed,

UlOl IC-286
u102 IC-288
u103

u201. u202
U203. U209

u204 IC-284

IC-287
IC-226
IC-103

SIDE VIEWS OF CALIERATION ADJUSTMENTS

FIGURE 5-2

5-6. TROUBLESHOOTING

The troubleshooting instructions contained I” this section

are Intended for quailfled personnel having a basic under­standIng ot analog and dlglt.8 c,rcu,trv used I” a prec,s,on
test ,nstrument. The ~ns,r”~t,o”s have been wntten to

asssr in ~solat,ng the defective urcuit or subclrcult. IsO-

lat,ng the defective component has been left to the tech-

DlCla”

NOTE

For instruments that are still under warrantv
(less than 12 months since date of shipment).
If the instrument’s performance IS outside of
specafications at any point, contact your
Ketthlev representative or the lactorv before
attempt,“g troubfeshootlng or repeli other

than battery or fuse repiacement.

5-6. Special Handling of Static Sensitive Devices

CMOS dewces are deslgned TO functlon ar’very high

Impedance levels for low power consumpt~on~ For th,s
reason. a normal static charge bu,ld up on vour person or
clothing can be suff,cient 10 destrov these dev,ces. The
foliowlng steps hst the static sens~twe dev,ces ,n your

5-7. Troubleshooting Procedure

This section contatns tables ilsttng step-by-step checks

of the major DMM circuits described in Section 4. Theory
of Operations The following steps outl$ne rhe use of these
tables and provide ~nstrucrion for orepanno the DMM
for troubleshoot,ng. Read all of thede steps & trow

bleshootlng the ,nstrument~
To troubleshoor the wwrumenf 11 $5 necessary TO dwas­sembie the 135 case. To do th,s foilow the
I” paragraphs 5-4-l. 5-4-2. 5-4-3.

A. Power Suoplv

Start off troubleshooting with the power supply in
Table 5-1 there are several steps and checks thaw,,,
verify If the power supply IS ProVldirIQ the appropriate
voltage to the c,rc~,trv. if all checks I” Table 5-l prove

to be correct then proceed to step 6,

8. The next step 1s to check proper operation of the d,s­play and the A/D converter, Check these c~rc~irs by

folIowIng Tables 5-2 and 5-3.

C. The signal condltlon!ng c~rcu~trv should be next in

hne to be checked. Problems with DCV or Ohms may
involve the attenuator. Follow Table 5-4 for DCVtrou­bleshootlng procedure and Table 5-5 lor Ohms
troubleshoot,ng procedures

NOTE

Make sure that rhe PC board 1s free of contam­t”a”ts (oil. dirt. etc.). Contaminants on the PC
board wil degrade performance on DCV and
Ohms ranges.

steps

outlined

5-2

MODELS 135/l 76

D, Problems with AC v&age or AC current may mvolve

the AC converrel~ Check rh,s c,rcu,f by follow,ng Table

5~6, If the prOblem ex,sts w,,h AC current Only see

step E

Ed If problems occur wth current readings. check the

shunts and related c~rcu~ti” as ouri,ned I” Table 5-7,
It should be nored that AC and DC current ranges use
the same shunts. theieiore problems w,,, occur on the
same ranges if The Shunts are at fauli,

F If a gross iallure ewsts rhaf ,nd,cates a poss;b,e blown

fuse. refer IO paragraph 5-9 for tlJse replaceme”,
lnsrructions.

G. Ail measuremenrs are referenced IO analog common

(COM (“put jack) unless otherwse noted I” tables.

WARNING

Some of the procedures in~thefollowing tables
require the use of high voltage. Take care to
prevent contact with live circuits which could
cause electrical shock resulting in injury or

death.

MAINTENANCE

step

t

2
3
4
5
6

7

Item/Component

J1019

SlOl

lJ102. ptn 1
CR1 10. cathode
u103.

Pl”

u103. pl” 8
CRlOl. cathode
c104. +terrmna, outpur

step

Item/Component Required Condillon

1

2 UlOl. 1 PI”
3 UlOl. 5

4

pl” Backplane. IOOHz -3OOHr

UlOl pins 5 volt sq”arewa”es I” or O”,

2. 3. 4.6-26. 37.40

5 U201 9 and 13 pins

u202 psns 1, 5. 9.

: 3

6 u202 2. 6. 8. pins

12

POWER SUPPLY CHECKS

TABLE 5-l

Rewired Condition

I

Remarks

Connected to a fresh +SV

battery
Turn on power
+5 Volts *5%
+1~25 “01,s +5%

5

-5 Volts ?5% lnverlel Ourpur
+5 volts 25%
+a.4 volts +I 0%

Retere1ce Lener
From U102

Voltage Doubler

TABLE 5-2

DISPLAY CHECKS

Remarks

Turn on Power. select any
funcflon or range excepr
ohms.
+5 volts ?5%

square wave.

Of phase wtth backplane
SIgnal
Backplane Waveform

Bar. rnl”“S

sign

snd dec,mal

PO!“, drivers

ApproprlateOPl,neh,ghO

Select all ranges
10 check all deco
lmal pOl”tS~

MAINTENANCE

MODELS 135/176

Step I

2 Momtor &play

3

2
6 Monitor Display

7 UlOl p,n 32
8
9 U21 3 pm2

10
11 U213 p,n 5
12 U213 pin 7

13 External DC supply
14

15 u213 PI” 1
16 U204 p,n 12

Item/Comrmnent Rewired Condition I Remarks

1

u214 pin 6

u211 p,n 15

U21 1 short p,ns

5 and 15

C206

U213 pin ,

such as 343A
Monmr Display

A/DCONVERTERCHECKS

TABLE 5.3

Turn on Power. select 2VDC
range. short “01,s input.
,OOOO +l d,git

0000 “Oh

+1 00 VOITS

1.0000 +lO d,g,ts

0 to +5 Volt square wave Clock s,gnal

1 OOKHz +lOOHz

0~0 Volts *I OOm Volts
O,O Volts fl OOm Volts

1VOll to.3 volts
0 volts
0 Volts *40m Volts

Apply +1.9OOOV

1.9000 tl dig11

Waveform as shown in
Fzgure 5-3.
Waveform as shown m
Flgure 5-4~

Buffer Ou1put. A/O
Input

Reference Output
Connects reference
output toA/D input

If steps 4 and 6 are

correct Then the
A/D 8s func,ion,ng
properly,

Stored Auto Zero
Voltage
Integrator Sum­mtng Junction
integrator Outpvt
Buffer Input
Buffer Output

Calibrarlon Point

If different check
U214 input
lntegraror OUtput

Comparator Output

!NTEGRATE
rl OOMS-j--200MS ,

;;: ~=&ON

INTEGRATOR OUTPUT WAVEFORM

l COMPARATOR WAVEFORM ’
I

I

INTEGRATE

COMPARATOR OUTPUT WAVEFORM

1 OOMSEC ZOOMSEC

SIGNAL

REFERENCE

INTEGRATE

I

FIGURE 5-3

IS A LOGICAL 1

DURIYG RAMPING

SIGNAL

I

REFERENCE AUTO ZERO OF

INTEGRATE

I
I

FIGURE 5-4

I

I
I

I
I

5-4

MODELS 1351176

MAINTENANCE

For troubleshooting the DC anenuator tallow Table 5-4

-_- .._...__ _._ -.._

Sft3P Item/Component

I

2

External DC supply Apply + 1 ,900O Volts
such as 343A

3 U214

4

z

i
9 U214 p,” 6 1 000 volts f10 dlglts i .:dffer OUrpUt

L

pin 6
External DC supply
such as 343A 19 000 VOIIS~

U214

p,n 6
External DC supply
such as 343A 190.00 Volts,
U214 pin 6 1 ,9 Volts Z20 dlgits
External DC supply
such as 343A

Since ACV and DCV use the same attenuator. ver,f,cat,on
Of the DC arte”ua,or IS sufflclent to unsure that the AC
atten”aIOr IS functlonlng properly,

Required Condition

Turn on power. select the
ZVDC range, Short the #“put
and adjust R207 for ~0000 at
OUtpUt Of u2 14

Cai~brated Inpu,

1.9Volts

Select 2OV range Apply

1~9 volts A1 0 d,gns

Select 2OOV range Apply

Select 1OOOV ranges Apply : -aI,bra,ed input

1000 VOIW

AC Converter

Buffer ourput
Cal,brared lnw,

Buffer OUrpUt
Calrbrated Inpu,

j/ 3uffer output

TABLE 5-5

AC ATTENUATION CHECKS

step

Item/Component

Required Condition

Remarks

Remarks

I

2
3

4

5

6 External AC source Select 20VAC range and

7

8

9

10 External AC source Select 1 OOOVac range and

Ii

Monitor Display
External AC source Apply I .OOOO “01, RMS a,
such as WP745A 1KHz

Wiper of A 107

R105 pin 9 +1 i/Ott DC

such as H-P745A
Monitor Display 19.ooov Nominal

External AC source
such as H-P745A
w,th 746A

Monitor D~splav
WP745Awlh746A

Momtor Display

Select the 2VAC range and
short the input,

0000 ?5

1 Volt RMS nom,nai

apply

Selecr ZOOVAC range and
apply 190 OV at 500Hz

190,oov Nominal

d,g,ts

19,OOOV at 500Hz

apply 5oov at 1 OOHZ

500 ov Nominal

R 1 1 1 zero ad,ust
Caiibraied input

AC Buffer Output
AC Converter Input

output 01 u 104

Gatn of U104 IS ad­,“SWd to prowde + 1
VDC ior 1 Volt AC
Calibrated Input

Cailbrared input

Calibrated lnpu,

MAINTENANCE

MODELS 135/176

­step

6

7
8
9

li)

11
12
13
14
15
16

Item/Component

Monitor Display
A105 pin 4
lnout HI to LO

Input HI to LO

1 K~precis~o”
res,stor
Monitor Display

lOK.Qprecision
reSIStOr
Momor Display

1OOKRpreclsion
res,stor
Momor Display

1000 K~precis~on

ft?S,SfCJf
Mon,tor D~splav

IOMnprec~sio”

resistor

Momtor Display

OHMS ATTENUATION CHECK

TABLE 5-6

Required Condition

Check A/D Converter
Select the 2kR range and
short the ,“D”t
.OOOO _Cl digIt

Approximately 2.5 Volts

Remove short and connect

ammeter from ln~ur HI to LO.

Measure open circuit volt­age 3.5 Volts max

Apply to input

1 .OOOO *30 dtgits

Select 20KR range and awl\
1 OKR to input

10.000 ?22 digits

Selecl 200K.0. range and
apply 100 KR to Input

100.00 +22 dlglt

Select 200KQ range and
apply 1000 K.Q to ,“put

1000.0 f22 dig,%

Select 1 OMa range and
apply 1 OMS7 to the input

10.000 2102 digtfs

If incorrect check
QlOl. RTlOl or
Q204

Calibrated
res,stance

Checks accuracy of

Rl16-1Kfl
Calibrated
resistance
Checks accuracy of
R116 -9Kfi
Calibrated
reSlStance
Checks accuracy of
Rl 16.90KR
Calibrated

resistance

Checks accuracy of
Rll6-9OOKG
Calibrated
resistance
Checks accuracy 01
131 1 B-SM.SIleakage

of Q204 and leak­age of c-21 1.

step

1

2 A112.Rll4

4

Item/Component

FlOl

External DC voltage

I

Disconnect the test leads and turn the 135 off
before replacing the battery or fuse. Put the

covers back into place on the

compartments

before resuming useof tne instrument.

5-6

(

:RENT SHUNTS CHECKS

Required Condition

Contlnuilv

TABLE 5-7

Correct shunt value for
specified range

Turn on power and select

DCA. 20mA range
0 to 1 Volt

. . .._....._..........____._

5-9. Battery and/or Fuse Replacement

A. A 9V battery IS supplied with the i”str”me”t but not

Remarks

Apply a know” , /2
full scale curient
and measure volt­age across Stl”“l

Clamping mmt

CICC”, at +-0,7 Volt5

lnstalied.

cover from the battery cOmpartme”t by slidang it off I”
thedIrectIon of the arrow located on the battery cover
The battery connecior snaps on and off rhe term~nai

To mstall or replace the battery. remove the

MODELS 1351176

MAINTENANCE

of the battery Improper insfaliat~on oi rhe batlery ~111
cause the connecting wires IO be severed by excess
strain. Proper installation requtres that the battery
be posmoned ,n such a manner lshown in Ftgure 5-5,

that the leads protruding tram the boor of the battery

connector lace reward the ourstde of the battery come

parrme”,~ If the insrrume”, IS going to be stored for
a long period of lime or I” a high remperature en”>ro”­men,. remove the battery to prevent leakage damage

FIGURE 5-5

BAITERY INSTALLATION

‘3 A ,75 amp fuse protects the 20mA range. To gatn

access to the fuse. remove the fuse comperfment
covei in the same manner ae remowng the battery
compartment cover Remove the fuse by puillng out-

ward on the plasf~c tab that encircles the fuse body

install the pIasr,c tab on the “ew fuse and snap the
fuse back into ihe luse holder. DO not replace the fuse
w,th a h,gher rated value or mstr”mentdamagethat IS

not covered by warranty may occ”r~

NOTE

Some fuse covers incorrectly 8ndlcate the
fuse value at 2A~ 0,75A is rhe correct value.

5.10. MODEL 176 CALIBRATION

The Model 176 recommended callbratlon equipment IS
iisted ,n Table 5-1 Alternate equipment ma” be used.
However. the accuracY of ihe alternate equipment mus,
be at least 3 ,,mes better rhan the Model 176’5 speciflca­nom or equal to Table 5-l speclflcatlons.

5-l 1. Environmental Conditions

The enwronmen~al condittons lhat are requred IO call­biate the 176 are outlined I” paragraph 5-3~

A Turn off rhe power (/I ihe Model i 766 ,s ,ns:a!ied,

d%sco”nect :he hne ‘oral

8 Turn Ihe instrumenl o”el so that Ihe bo!!om cover 1s

bang up. loose” the iour screws in the bO,lOrn pane,

C Hold the top and bottom covers together 10 prevent

the,, separai,on an* tu,n me 176 over 10 norma, pos,~

tion

I

Selecl the DCV funcrion and the 20V range Place
a shorl across Cl 18, Ad,usr R125 for a d~spiav ot
0~000 RemovetheshortfromC: 18afrertheaa!usr­me”, IS made,

2,

Select the 2V range and short Ihe ~rpul lerm~na~s
,HI and LOI Ad,usi R 102 for a d!spiav of 0000

3~

Select Ihe ACV functjon and the 1OOOV range Wilh
rhe short s~,il apphed :o the input lerm8ne!s ac,~s,
Rl 18 ior a dtsplay of 000 0 Remove Ihe snort from
the tnput term,“als (HI am, LOI aflei the ad,ustmeni
IS made~

4

Select the DCV i~nct~on ano the 2V range ADDIY
+I 9000Vtothe~npurterm~nalsIHIandLOlfromihe

DC cal,bra,or Ihem A Table 5~ 1, Ad,usr R: 30 lo< a
dtsplav 01 1 9OOOV
Select the 20V range and applv * 13 OOOV 10 the

5.
input terminals (HI ans LOI from the DC caf~brator
lltem A. Table 5-l) Ad,usl RI07 for a Ctsp:ay zi

19~OOOV

6,

Select the AC” f”nc,~o” and the 2V range ADDI~

IV at IKHZ 10 the ,npur ,ermlnais ,HI ar* LO1 fro”.
the AC caI,bralor (Item So Table 5. Ii Adiusl 8 1 13
for a dtwiay of 1 0000

7,

Select the ZOOV range and apply 100 OOV a! 5KHz
rothe ,npu, term,nals from the AC caltbraror (Item 6,
Table 5- 1 ,. Adlust C 106 for a readlnq 01 100 OOV

8

5-12. Calibration Procedure

Cailbratlon should be performed by quaIlfled personnel
usmg accur.ate and r&able equ~pmem Perform rhe fol­lowfng procedure and make the adJustmenrs mdlcated to

ca,,braterhe Mode, 176, Togan access tothecaiibrarlon

adjustments. the 176’s top cover must be removed. Use
the folIowIng procedure 10 accomplish thts

WARNING

To prevenf a shock hazard, all test leads
should be removed

before removing

Do not exceed maximum allowable tnput

volrage. Instrument damage ma” occ”r~

Maximum allowable inputs are stated I”
the specifications.

from

the fop cover.

CAUTION

the input terminals

5-13. MQDEL 176 TROUBLESHOOTING

The troubleshoot,ng ~nstr”ct,o”s conralned 1” this sec.
tto” are (“tended for qualifled personnel hawng a Dasx
“nderstandmg ,,f analog and d,garal CI~CUI!‘” “se0 in a

precision ES, ,ns,rumen,, The ~“str”clions a”4 iables

have bee” wr,tfen to assts, ,n isolating the defective c!r­CUII or subc,rcu,t. lsolar,ngthe defectwe compo”en1 has
been Iefl to the technictan

NOTE

For ~nsrrumenrs that are sttll under warlaniv
iless than 12 months since dare of shipment,.
11 the mstrument’s performance IS ouwde of

SpeClflCatlOnS at any pot”,. contact YOU,

Ke,thley repre~entaftve or the faclory before

atremptlng mubleshoomg or repair other

fhan battery or fuse replacements

MAINTENANCE

MODELS 135/176

5-14. Special Handling of Static Sensitive Devices

CMOS dewces are deslgned tp function ar very high

mpedance ievels for low power consumption. For thls

reason. a normal stal,c charge burld “pon~ou, person or
clothmg can be suffictent 10 destory these devices. The
followmg table IS a ,151 oi the stattc senstrive dewces
iocated I” your 1 76~ In~tru~f,o”s on how to avo,d damag­~“g these devices when they must be removed or replaced
are located I” paragraph 5.6,

static Sensitive oev1ces

Reference Deslgnarlon Kelrhiey Part Number

UlOl u104

u105. U106

u107

u112.u113.Ul18 31@7-1

Ull4

u115

U116. u122 IC-103

“117

VI19 IC-138
u120 k-139
u121 P-102
U123 HZ-288

X-226
IC-149
lc-286

IC-284
IC-285

IC-287

5-16. Troubleshooting Procedure

This sectton contatns tables hstlng step-by-step checks
of the ma,w DMM ~jrcu,,s described I” Section 4. Theory

of Operamh, The followng steps outline the use Of these
fables and pro”,de ,nsrr”cf,pn for preparrng the DMM for
tux,b,eshoof,ng. Read all of these steps before trouble­shooting the instwment~
To troubieshopt the instrument iris necessary to remove
the top cover. Th,s can be accompl,shed by foilowng the
procedure outltned I” paragraph 5-1 1A. B. C and D,

A. Power Supply

Start off troubleshootmg wlfh the power supply. In
Table 5-8 there are several steps and checks that WIII
ver,fy If the power supply ,s provtdmg the approprzate
voltage to the ctrcu~try. If all the checks I” Table 5-8

prove TO be correcr. then proceed to step B.

8. A/Q Converter
The next step IS to check proper operation of the A/D
convener, ChecktheA/Dco”“eirerbyfollowtngTable

5-9,

C. The next step IS to check the slgnal conditlonlng cur-

cuttry Depending on the discrepjancy. s1xt wth the
appropriate attenuamr, Table 5-10 outlines the DCV
attenuator. Table 5-l 1 outlines the ACV attenuator
and AC converfer, Table 5-12 outl,nes the curreni
arfenuatlo”~

0. Ohms &urce
The Ohms source troubleshooting procedure IS out­lined I” Table 5.13,

E. If a gross failure exnts that tndxates a possible blown

fuse. refer to oaraaraoh 5-16 for fuse repiacemenr

POWER SUPPLY CHECKS

TABLE 5-S

step

Item/Component

I I

1

2 Batteries

Tesr Point 1

3

TPl

4 TP2

TP3

5

6 TP5

7

U109 pin 7

‘All voltages are measured wth respect to (“put LO

Required Condition’

Turn on Power
x5v
>6.2V

+5.ov f20%

-5.ov C20%

1,2ov ICI 1,25v

+a.4v nominal

Remarks

6 fresh ‘C” cells
CR1 10 check

Analog +5V check.
This is SuppIled
from the batterfes
through “123,
Analog -5V check.

This 1s supplied

from Analog +5V
supply via U 1 17,
Band Gap
ence Check
(CRlll)

Analog +8.4V

check supplied by
U 1 1 7. used only for
u109.

Refet-

5-8

MODELS 135/176

MAINTENANCE

A/D CONVERTER CHECKS

TABLE 5-S

step Item/Component Required Condition

(HI and L6

3’
4

9

10

11

12

13 u115 otn 15
14

15

16

Mon~for Dis~lav

TP6 +o~ooolv
TP7

Ul20 ptn IO
u107 01” 28

u115pin 1 5Hz. 0 to +5V square wave

Ul 11 bin 3
VI 11 p>n 7

Ul 11 p,n I

OOOOV iI dig,r

*0,0001v

IOOKHz nominal. 0 to +5V

square WaYe

I OHZ. 0 10 +5v square wave

2~5Hz. 0 to +5V squarewave
+70mV
230rn”
Nommal +1 2V

Remarks

UllO Input Buffer
Zero
Inpu, to A/D

0”

17
18

19 “111 PI” I

L

-

FOR +I VOLT INTO THE A/D CONVERTER

External Voltage
Source (343Al
Ul 11 p1n 7

FIGURE 5-6

Apply + 1 ,OV to Hi and LO

l”P”!
Ftgure 5-6
Figure 5-7

SUFFER WAVEFORM

I

+I 2”

NOMINAL

FIGURE 5-7

INTEGRATOR WAVEFORM

MAINTENANCE

MODELS 135/i 76

DC ATTENtIATOR CHECKS

TABLE 5-10

step

Item/Component

I

2 External Source
3

4 Monitor D,splay
5

6 Externel Source

7 Monmr Display

8
9 External Source

10
11 Select the 1000VDC range
12 ml;l Source

13 Monttor Display

1343Ai

TP6

1343Al

(343A1
Monitor Display

Required Condition

Turn on

2VDC range

Apply +1,9V

1,9v Input Buffer Check
I .9ooov R 130 reference

seiecr the ZOVDC renge

Apply + 19V

19.000v R107 divide by 10
Select the ZOOV range

Apply + 1 SOV

190,OOV nomrnal

Apply 1 OOOVDC

1 OOO.OV nominal

power and select

TABLE 5-l 1

AC CONVERTER CHECKS

step Item/Component

Required Condition

Remarks

adjust

adjust

Divide by 100 check

Dlvlde by 1000 check

RWWirkS

1

2 External AC Source

3
4

5
6

7

8

9

10

11
12

(745A)
U108 lx” 7
Rl 17 PI” 9

External AC source
(745Al

Momor Display
External AC source Select 20VAC range and

(745A1

Momor Display

External AC source
1745A)
Monitor Display

External AC source Select the 1 OOOVAC range
(745A and 746A)
Momtor D~play 1 ooo~ov nominal

Turn on powerandselectthe
2VAC range

Apply ,Vrms at 1 KHz

1 ,OVrms

+1 .OVDC

Select the WAC range and
apply 1VAC at 20KHz

i .oooov “Omlnal

apply 10Vrms at 1OKHr

1 O.OOOV nominal

Select the ZOOVAC range
and apply 1 OOVrms at 5KHr

100.00 “Omlnal

and apply 1 OOOVAC at , KHz

Cailbrated input

Umty Gain Buffer
Output of AC con­verter, R 1 19 IS ad­justed to gwe 1~0
VDC qufp”t for 1 ,O
VAC input. (High
impedance measur­~ng here will load
down the reading.
Measumg at out­out Of UlOS Wlil
cause oscillation.

Htgh frequency re­sponse ~compensa­rionC106. Cl051

High frequency re-

spowe icompensa-

t~on C 106. C 104,

High frequency re-

s~onse

tfon C106. C?O3)

(compensa-

5-10

MODELS 135/176

MAINTENANCE

TABLE 5-l 2

CURRENTCHECKS

Item/Component

R108 PI” 4

RlOB pl” 5
Ul18p1” 15
U106 p,n 6

step

Item/Component

1

2 “108 p,n 1

I I

Required Condition

Turn on power and seiect

the 2mADC range

1 OOR “Omlnai

+I ov

+o~lv
+o IV “Omlnal
ov

TABLE 5-13

OHMS CHECK

Required Condition

Turn on power and selec,
2KR range
+3v nominal

+3v normnai

+3v nom,nai

Remarks

Remarks

Ohms reference
check
Check for 0 I OS
Short
RTlO, CO”,l”“~1’,
check

5-16. Battery and/or Fuse
To replace the batteries the top cover musl be removed~
To do this follow the pmcedure outI,ned I” paragraph

5-1 1 A. 6. C and D. Install the bat,er,es 8” the holder as
shown I” Figure 5-8. lnstallar~on of rhe battery pack is
shown I” Figure 5-g.

To prwenf a shock hazard. all test leads should
be removed from the input terminab before

removing

the top cover.

be3 W-6

BAlTERY INSTALLATION

Replacement

WARNING

BAlTERIES

FIGURE 5-S

3a313

BATTERY

HOLDER

\

BATTERY

CONNECTOR

i

30307

STANDOFF

FIGURE 5-S

EAlTERY PACK INSTALLATION

WZR c

“1

MAINTENANCE

MODELS 135/l ?6

5-17. CURRENT FUSE REPIACEMENT

WARNING

To prevent a shock hazard. disconnect all
circuits from

the

INPUT terminals before

removing current fuse.

To remove the c”r,ent Iuse. turn the DMM we, and lay ,r
carefully on 11s top, Insert a small screwdwer blade xnto
rhe slot on rhe fuse holder. press gentlvand turn I ,4-t,,,”
counter-clockwise. Lift ihe holder
receptacle The fuse can now be removed for checkfng or
replacement. Replace with one of the tollowing types:

A. U,S.A, Use 3AG. 250V. 2A. Normal Blow

6. Europe Use 5 x 20mm. 25OV. 2A. Normal Slow

and fuse out of

the

CAUTION

lnstaii,ng a higher rated

specified could result m damage to the
Instr”rne”t,

fuse than the one

SLOT

TV}- 259

HOLDER

2A. 250V

The Turns ram between the primary wmdlng and the

secondary wndlng IS approximately 5 to 1. Measured
from the pr~marv co11 designated by pins 8 and 1 1 to sec­ondary

co11 designated by pins 4 and 6.

5-19. Rotary Switch Rotation
Rotary switch S103 may be ConfusIng when trying to

visualize the rotation of the contact wipers.

Ing Figures illustrate the five dlfferent posmon~ of both

sides of 5103.

The follow-

FIGURE 5-l 1

SWITCH S103 IN THE OHMS POSITION

CURRENT

FUSE

REMOVAL/REPLACEMENT

E-18. MODEL 1766 TROUBLESHOOTING

FIGURE 5-10

The Model 1766 Battery Ellmtnator troubleshooting 1s
relar~velv simple when followng the steps outlined in

Table 5-l 4~

TABLE 5-14

MODEL 1766 TROUBLESHOOTING

I stw

Item/Component

F201 I~ne fuse
P1006

Emliter of Q201

ContlnuitV

Plugged [“to love recerxacle.

Tunbn power

+a.5v “Ominal

1 CathodeC202 1 ‘9~lVnominal

SWITCH S103 IN THE ACA POSITION

FIGURE 5-12

FIGURE 5-13

SWITCH S103 IN THE DCA POSITION

Required Condition

5-12

MODELS 1351176

MAINTENANCE

SWITCH 5103 IN THE ACV POSITION

FIGURE 5-14

FIGURE 5-15

SWITCH S103 IN THE DCV POSITION

MODELS 1351176

Section 6. Replaceable Parts

6-1. GENERAL

Th,s section contains ~nformar~on for ordering iepiace­menf ~arrs toi the Models 135 and 1 76. The oarrs iists
are &rated from each other I” order IO avojd &ius~on.
The paits lists are arranged i” alohabetlcal order oi the
civmt deslgnatlons of theta components. Table 6-4 lists
the components of rhe Model 176. Table 6-5 lists the
components of the Model 135. A cross reference IIS, of
manufacturers. mcludlng the,, addresses ~sgwen #“Table
6-1

6-2. Ordering Information

To place an order or to obtain mformatlon concerning

repiacemen, parts conracr yo”r Kejrhley ret,resentattve
0, the factory See the inside Iron1 cover tor addresses.
When ordertng tnclude the following lnformatlon~
A. Instrument Model Number

6-3.

Factory Service

6-4.

Schematics

The Model 176 schematIc and PC layout are !oca~ec jr
page 6-S and page 6-10 respeci~vely The Mcde! ‘35
~chematrc and PC layo~,s are located on oageb- 1 i 6.: 2
and 6-1 3 iespecwely. The Model 1766 schema,,‘ is
located on Page 6.14~

MFR

Code

A-8

ACI

ERN

CAD

CLB

CNW

DLE

EC1

EDI

CROSS REFERENCE OF MANUFACTURERS

Name and Address

i

Alien-Bradley Carp,

,

i/ltlwaukee. WI 53204

i

imer~an Components. lnc
Zonshohocken. PA 19428

(

3ourns. 1°C~

E

i,vers,de. CA 92507

f
(

:addock

f

qtverslde. CA 92507

(

:enrralab DlVlSml

h

Ailwaukee. WI 53201
:omnental Wirt Electrontcs

(
\

Narmmster. PA
Iale Electronics

[

c

:olumbus. NE 68601
liecrro-cube. Inca

E

;a” Gabriel. CA 91 776

5

E

,

Federal
SUPPlY

Code

01121

14298

80294

19647

71590

79727

91637

83701

83701

TABLE 6-l

MFR

Code

INT

IRC

L-F

MEP

MDW

MOT

NAT

NIC

Name and Address

Lirtle Fuse Inc
Des Plans. IL 60016

MBDCO. Inc
Morr,srown. NJ 07960

Mtdwest
Muskegon. MI 49443

M~to,da Semi PrOd”CIS~ Inc
Phoenix. AL 85008

Namnal Sern
Santa Clara. CA 94086

Nlchlco” Carp
Chicago. IL 60645

Components.

Carp

Inc

Federal
SUPPlY

Code

32293

I5238

i5915

80031

047’3

18324

EFJ

ERI

GEE

E

I F Johnson

b

Vaseca. MN 56093
Iile Technological Products

E

Irle. PA 16512
;enerai Elecrrtc Carp

(

;yracuse. NY 13201

:

74970

72982

03508

PNC

P&B

PLY

Pane1 Components
Berkeley. CA 947 10

Potter and Brumfield
Pr~nceron. IN 47670

Plessev Capacilors
Wes~lake Village. CA 9 136:

COiP

REPLACEABLE PARTS

MODELS 135/176

MFR

Cod-2

RCA

R&H

RIG

SHG

Name and Address

Federal

WY

RCA Corporar~on

Moorestown. NJ 08050
Reeves and Hoffman

Carilsle. PA 17013 92567
Rlchey Electronics

Nashvtlle. TN 37207

Shtgoto
New York. NY 10036

02734

29309

TABLE 6-2

MODEL 1359 PARTS LIST

) Cky 1 Keithley P/N 1 Schematic Designation 1

IC-286
IC-288

31847-1

K-226

30985A

TG-138

RF-38
RF-28

FU-14

BH-29

PA-130

RT-7

CR103. CR108. CR109

UlOl
u102

u210. u211. u212

u201 -u202

CRllO.Rl17

0104

CRlOl. CR102.

CR104-CR107

FlOl

J1019
RTlOl

MFR

Code

SPG

T-l

TRW

Name and Address

Sprague Eiectr~c Co,

Vlsalla. CA 93278
Texas Instrument

Dallas. TX 75231
TRW Electra Components IRC

Boone. NC 28607

Descriotion I

C0llnter

CMOS OP Amp
Analog Swnch.
Selected IC-283
Excius~ve OR gates
Resistor and
Zener D&ode

Transistor
Diode
Diode

Fuse. 7% 3AG
Battery Clip
Packing List

Thermwor

Federal

S;W&

14679

01295

11502

6-2

[ CXY. 1 KeithlevP/N

K-286
K-288

31847-1

(C-226

30986A

TG- 138

RT-7

RF-39
RF-28
FU-13
FU-48

PA-1 29

MODEL 1769 PARTS LIST

TABLE 6-3

I

Schematic Desianation 1

u107
u123

U112.Ul13.Ul18

u101-U104

(CR1 11. Rl 13)

a104

RTlOl

CR1 10

CR102-CR109

FlOl
FlOl

- _____- _ ._,.

COUIX~~
CMOS OP Amp
Analog Switch,
Selected IC-283
Exclusive OR gates
Resistor and
Zener Diode

Transistor
Thermistor
Diode
Doode
Fuse. 2A-3AG
Fuse. 2A. 5x20mm
Packing List

MODELS 135/176

REPLACEABLE PAPTS

Circuit

Desig.

BAT

Cl02
Cl04
Cl05

Cl06
Cl07

Cl08
Cl09

Cl10
Cl11

Cl12
Cl13
Cl14
Cl15
Cl16
Cl17
Cl 18
Cl19

Cl20
Cl21
Cl22
Cl23
Cl24
Cl25
Cl26
Cl27
Cl28
Cl29

El30
Cl31

El32
ER102
ERl03
zfl104
ER105
3R106
:I?107
ZR108
3RlOS
:RllO
‘CR1 11

:Rl12

REPLACEABLE PARTS LIST

PC.r;Rri - Sm-!FMA+l~ 1”9A-m

- --- --. .-.....,.- --“-,-

Description Location

Batrer” I .5v “C” Cell

.Oll.lF. 6OOV Polycarb
39Op. 1 OOOV. Cer D

1 .SP to 157p. 250v

.5P 10 I .5p. 2ooov
:02. 1 OOOV. Cer D Bl

1 OP. 1 OOOV. Cer D
1 OPF. 20V. ETT

1 OpF. 2OV. Em Cl

25OuF. 25V. Alum
,OluF. 1OOOV. Cer D c2 14/D4

.lpF. ZOOV. Polycarb

15OP. 5oov. Cer D Dl

5p. 5oov. Cer 0

1 OP. 1 ooov. Cer D

l!aF. 50V. Polycarb
1uF. ZOOV. Poiycarb

~22~iF. 5OV. Polyprop C5 2l/A5

.luF. 5OV. Polycarb

100~. 1 OOOV. Cer D

,lpF. 1 OOV. Mtl Poly

.047/1F. 1OOV. Mtl Poly

lO/iF. 25V. Alum

.Ol. 1OOOV. Cer D

1OuF. 25V. Alum Fl
1 OuF. 25V. Alum
10!~F.25V. Alum

4.7pF. 25V. Alum
250~F. 25V. Alum
.OluF. 5OV. Polycarb D2 33/84

1 OpF. 2 5V. Alum
Rectlfler. 75mA. 75V
Rectifier. 75mA. 75V
Rectlfwr. 75mA. 75V

Recrlfler. 75mA. 75V
Rectifier. 75mA. 75V
Rectifier. 75mA. 75V
Rectifier. 75mA. 75V Fi
Rectifier. 75mA. 75V Fl 46/D4
Rectifier Hl
Low Voltage Reference El 48/D5
iZi?WBi
Rectlfler

Sch.

HI

B5 4/84
83
83 7/c4

82 8/D4

::

El 13/D4
Dl
Dl 17/E4

c5 18/84
84
84 20/85

D6 22/A5

:‘2
B5

Fl

Ei
01 31/D5

D2 32/D5

8
Cl 40/D3
c4 41185 T-l
c4 42185 T-l
D1 43/E4
Dl 44/E4

85 49/85

TABLE 6-4

PC-Board
Item No./

Location

6/84

S/D3

lo/D3
ll/D3

I Z/D3

15/D4
16/04

19184

23/C5
24/C5
25/C5

26/D4
27/E4
28/D4
29/D5
30/D5

34/E5
39/D3

45104 T-l
47/D5

Mfr.

Code

-

Ever­eady

P&B
CLB DD-39 1
EFJ

EFJ 273-l-l

SPG 5622.5VAA
CLB

ITT
ITT

NIC
SPG
ECI

CLB DD-151
CLB

CLB DD-100
ECI
ECI

TRW
ECI
CLB DO-101
PLY
PLY
NIC
SPG
NIC
NIC
NIC 25ULP.lOD.T

NIC
NIC
ECI

NIC
T-l

T-l

T-l IN914

T-l lN914

T-l
MOT
MOT

ITT

Mfg.

Desig.

935

4200F103M

187~0109-

005

102AM203M

DD- 100

Tap/F

35v. 20%

Tap/F

35v. 20%
25UlA25D.T

loss-sI5

625BlC:O4
DD-050
625BlA105

6258lC104
X363UW
625BlA105

160-O 1 MFD
160~047MFD

ZSUlAlOD-T

loss-s15
25ULAlOD.T
25UlAlOD-T

25ULA4R7

D-T

25UL4250

D-T
625BlA105

25AU250D-T

lN914

lN914

lN914

lNS14

lN914

IN914

1 N4006
LM385Z

IN5400 RF-34

BA-6

c-215-01
C.64~3300
C-284-1 9 1s

15 7P
C-184-510, 50
C-298- 02

C~64-10~
c-179-10

c-179-10
C-314-250

c-22. O!

c-221. !
c-22-1 501,
c-22-50
C-64.100
c-215.:
c-221. 1
c-269~ 22

C-215.’
c-64.loop
c-305 1
c-305-047

c-314-10

C.22~ 01
c-314-10
c-314-10
c-314-10
c-314-4 7

C-314-250
C-215. 0,
cR2:84-‘”

RF-28
RF-28
RF-28
RF-28
RF-28
RF-28
RF-28
RF-38
30386A

Keith@

Part No.

3R113
:Rl 14

‘CA1 1 1 IS part of a se, for the reierence c,rcult that IS selected at the facrory

Rectlfler 50/83

ZWlW

I

I

I

51/E3

ITT
In-r

I

IN5400 RF-34
IN7518

DZ-59

a-3

REPLACEABLE PARTS

Circuit

Desig.

Description

TABLE 6-4 CONTINUED

PC-Board

Item

No./

Location

Mfr. Mfg.

Code De&.

MODELS 135/176

Keifhley
Part No.

FlOl
FlOl

JlOOl

QlOl
0102
a103
Q104

RlOl
R102

RI03
R104

R105
R106

R107
R108

R109
RllO
Rlll

Rl 13
R114
R115
R116
R117
R118

R119
R120

R121
R123
R124
R125

R126
R127
R128
R130

a131
R133

1

1134

I

3135
R136
R137
R138
R139

R140

Fuse. 2A. 25OV. 3AG.
U.S.A. Models
Fuse. 2A. 250V. 5 x 20mm
European Models

Battery clip

Transistor. NPN
Transistor. PNP
Transistor. NPN
Transistor. NPN

Thick Film

lOOK. 10%. Cermet

Trimmer
470K. 10%. 2W. Comp

9R. .l%. 1/2W. MtF

9052. 1%. 1 /8W. MfF
,0999R. ~899152

50K. 10%. Cermet
rrimmer
rhick Fiim

1K. .l%. 1/8W. MtF

SK. .l%. 1/8W. MtF
90K. .l%. 1/2W. MtF
Selected
300K. .l%. 2W. MtF
10K. .l%. l/lOW. MtF
1 OOK. 10%. 2W. Comp
rhick Film
5OK. 10%. Cermet
rrimmer
zoon. 10%. Cermet
rrimmer
IOK. .l%. 118.W. MtF

3.lK. .l%. 1/8W. MfF
316K. 1%. 1/8W. MtF
I M. 5%. 1/4W. Carb
IOOK. 10%. Cermet

-rimma
?OK. 5%. 1/4W. Carb
17K. 5%. 1/4W. Carb
12M. 5%. 1/4W. Carb
!OOn.. 10%. 3/4w

-hick Film
17K. 5%. 1/4W. Carb

OK. 5%. 1/4W. Carb

OK. 5%. 1/4W. Carb
1 OK. 5%. 1/4W. Carb
10K. 5%. 1 /4W. Garb
1 OK. 5%. 1/4W. Garb

1 OK. 5%. 1/4W. Garb
47K. 5%. l/4W. Carb

A3
A3

Hl

C6

:6”
A5

H3.4
85

85
E

Al.2
E

83
81

::

2”
c2

Cl

Cl

Cl
::

c4
c4

H2
H2
Cl

L-F
PNC

52/E6

59/A4
60/B4
61/A4
62/C4

67/02
68/A4

69/84

70/83 IRC
71183 DLE MFF-l/8

72183 DLE
73/84 BRN

74/84
75/B4
76/C4
77/c4

79/D4
8O/C4
81/D3

82/D3
83/D3

84/D4

85/04 BRN
86/E4

87/D4
89/A5
9005
91165

92/85

93/85
94/c5
96/D4

97105

98/A4
99/A4

1 OO/A4

lOl/A4
102/A4

103/A4
104/A4
105/D5

SHG

NAT
MOT
NAT
G-E

Epitek
ERN

A-R

CAD
DLE
DLE
IRC
K-l
ACI
ACI
A-8
Epitek
8RN

DLE
ACI

4-8 HE
3RN

MEP
4-B H8

3RN
ipitek

q-6
j-8

l-8
A-8
A-9
A-B
A-E
A-B

312002
034~1519

YOS/1893

6ASE-12
2N3904

2N3906
2N3904

GES-58 18
TF-130

3386-F-l ­104

HE4745

SPR-1012
3386F. l-053

TF- 126

MFF-l/8
MFF-l/8

C-3CM-2
HB -

TF-123

3386F.l-053
3386F.l-201

3386F-l-104
CR25

3006P.l­201
TF-124

-I6

-18
iE

HB
HB
HB
HE
HB

FU-13
FU-48

H-28

TG-47
TG-84
TG-47
TG- 138

TF-130
RP-97.IOOK

3-3-470K
R-l 35-9

R-l 79-90
q-297

?P-97.50K
TF-126

3.179.1K
3-l 79.SK
q-1 35.SOK
30986A
?-267.SOOK
3-263-l OK
?-3-100K
TF-123
?P-97-50K

w97.200

-

-

t-1 79.20K
?-179.9.1K
l-88-3 16K
I-76.1M
1P-97.100K

I-76-201(
q-76-471(
I-76.22M
IP-89.200

‘F-l 24
i-76-471(
I-76.10K

I-76.10K

3.76.IOK
3-76-l OK
?-76.10K
3-76-l OK
q-76-471(

6-4

RTlOl

rhermlstor. 8mA. 500V.
‘TC

A2

105/c4

MDW

180Q10200

3T. ‘I

MODELS 135/176

TABLE 6-4 CONTINUED

Circuit

Desig.

SlOl

LJlOl
u102
u103
u104
Ul 05

Ul 06
u107 ( ~~~~

UlO8
u109 Linear OP AMP

UllO
Ulll
u112
u113
u114
u115
U116
u117

Ullt3
u119

1 Swtch

J FET OP AMP

I

Linear OP AMP

J FET OP AMP

1 CMOS, Two Input AijD 1 SEV

gates

CMOS.
CMOS.

I

no.aC

yacca
CMOS. D wpe Flip Flops SEV
CMOS. LOW POW OPAMP

I

YlOl

-

‘*Assembly consists of Batterv Holder BH-27 and a BatterY Holder Plate 303036
Front Panel Assembly

-

-

-

-

-

Crystal 1 OOKHz HZ
Batterv Holder Assembly

I

Front Panel

Overlay. Front Panel

Liqud Crystal Display
Connector. Zebra Strip
Liquid Crvstal Spacer

Description

1 SEV

CMOS. Ex;lus,ve OR gates
CMOS. Exclusive OR gates

CMOS. Excluswe OR gates
CMOS. Exclusive OR gates
CMOS. Quad 61laterai
Switch
CMOS. Ouad Bilateral H3
SbWCh
LCdCounter

Analog Mult,plexer
Analog Muluplexer
D type Flip Flops

J K type Fltp Flops

D type FIIP Flops

Voltage Converter

Analog Mult~olexer

lrlverk?rs

Two Input NAND

SEV
SEV 114/82

SEV
SEV
G3 117/82

1 F.GZ

Cl.A3
Dl
85
C.06
64

04
SEV
F2
D.E3
Fl

c4

SEV
SW

I

SEV

I I

I 107/c1 I CIR

113/A2
115/A2

116/82 RCA

1 lE/CZ
119/D2

120/D3
121/D4
122/A4
123/A5
124/85
125185
126/C5
127/C5
128/D5
129/D5
13”/R5

I 131/65 I RCA

132/l
133/l

134/05
135/D5

142/C5

-

-

-

-

-

-

RCA
RCA
RCA

RCA
RCA

INT
T-l
NAT
MOT
T-I

I

:5
35

-

-

-

-

-

-

RCA
RCA

MOT
INT

R&H

-

-

- -

-

-

-

co4070
CO4070
CO4070
CD4070
CO4066AE

CO4066AE

ICML7224
TL062CP
M308
LMl 1CLN
TL062CP

I

CD4069EE
CD401 I

CD4013
iCL7621

RH-170

REPLACEABLE PARTS

-

-

-

-

-

-

SW-429
309648

IC-226
IC-226
IC-226

IC.71F

,_ __”
IC-149

IC-149
lC~286

IC-279
IC-99

CR-15

303136”

30816D

30935c
DO-26

cs-376.3
314048

REPLACEABLE PARTS LIST

PC-567 - SCHEMATIC 30554C

Circuit Sch.

Desig.
c201
c202 loop. 1 OOOV. Cer D 5/D3

C203 1 op. 1 ooov. Cer D 6/E3

.lliF. 50V Cer

Description

LOCatiOn Location

Gl

TABLE 6-5

PC-Board

Item No./ Mfr.

4163

Code

ERI

CL6 DD-101
CL6

Desig.

8121-050 C-237. I

625.l04M
DD-100

Mfg.

Keith@

Part No.

C-64-1003
C-64.:Cp

REPLACEABLE PARTS

MODELS 135/l 76

TABLE 6-5 CONTINUED

Circuit

Desig.

C204
c205

C206

c207

C208

c209
c210
c211
CA201

CR!202
0201

Q202

Q203
a204

R201
R202

E2

R205

R206
R207

R208
R209
R210

R21 1
u201
u202
U203
u204
U205
U206

U207

U208

u209
u210
u211
u212
u213
U214

.lpF. 50V. Cer
1pF. 50V. Polycarb

1uF. 50V. Polycarb
~22pF. 50V. Polycarb
,lpF. 50V. Cer

.lpF. 5OV. Cer
~1uF. 50V. Cer
.Ol, 50V. Polycarb
Rectlfler

Rectlfiel

Trans,stor. NPN

Transistor. NPN

Transistor. PNP
Transistor. NPN

1 M. 5%. 1/4W. Carb

Thick Film

22M. 5%. 1/4W. Carb
47K. 5%. 1/4W. Carb

lOOK. 10%. Pot

Thfck Film

50K. 10%. Pot

1 OK, 5%. 1/4W. Carb

316K. 1%. 1/8W. MtF

1 OK. 5%. 1/4W. Carb
47K. 5%. 1/4W. Carb
CMOS. Exclusive OR gates
CMOS, Exclusive OR gates
CMOS. D type Fl!p Flops
CMOS. 0 type Flip Flops
CMOS. JK type Flip Flops
CMOS. lnverter
CMOS. Two Input AND
gates
CMOS. Two Input NAND
gates
CM%. D type Flip Flops
CMOS, Analog Multiplexer
CMOS. Analog Multiplexer
CMOS. Analog Multiplexer
, FET OP AMP

Linear OP AMP

Sch.

.ocation

65
c4
;z

85
F2

G2
84
85

Et5

c5
D5
c5
44

E6
SEV
Dl
D2
c5

SEV
45

34
35
35
46

;f?J
;EV

i4
jEV
iz
jEV
;EV

jEV

13

:4
15
:4
15
r5

PC-Board
Item No./

LOCatiOn

7/D2

8/E2

9/E2
lo/E2

ll/FZ

1 Z/F2
13/F2
14/F3
ltl/EZ

19/E2

33/E3
34/E3
35/E3
36/E2~

39/82
40/82
41/c3
42/D3
43103

44/E3
45/F3

46/E2
47/E2
48/F2

49/E2

52/82
53/02
54/B2
55/82
56/63
57/c3
58/B3

59/c3

60/D3
61/02
62/D2
63/E2
64/E2
65/F3

Mfr.

Code

ERI

ECI
ECI

TRW

ECI
ERI

ERI
ECI
T-i

T-l

NAT
NAT
NAT

G-E

A-B

Epttek

A-B

BRN
Epitek

BRN
A-B

A-B
A-B

RCA

RCA

MOT

NAT
MOT
RCA
RCA

RCA
MOT

MOT
MOT
MOT

T-l
NAT

Mfg.

Desig

8121-050

651.104M
62581~105
625BlA105
X363UW
625BlA
8121-050

625.104M
8121-050

625.104M

625BlA103

lN914
lN914

2N3904
2N3904
2N3906

GES-5818
HB

TF-129
HB

3386H-1..

104
TF-127
3386H-1.

100
HB

H-B
H-B

CD4070
CD4070
CD4013
74C175N
CD4027BC

CD4069BE

CD4081 BE
CD401 1
CD401 3BC

CD4053BC
CD4053BC
CD4053BC
TL062P
LMllCLN

Keithley
Part No.

C-237-,1
C-215-1

c-215-1
C-269-.22
C-237-.1
C-237. 1

C-237. 1
c-215-~01
RF-28

RF-28

TG-47
TG-47
TG-84
TG- 138

R-76.1M
TF-129
R-76.22M
R-76.47K
RP-1 1 l-100K

TF- 127
RP-1 1 l-50K

R-76.10K
R-88-3 16K
R-76.10K

R-76.47K

(C-226
IC-226
IC-103
IC-284
IC-285
r-139
IC-138

IC- 102

IC-103
31847-l
31847-Z

31847.3
IC-279
lC~294

6-6

YlOl

Irvstal. 1OOKHz

-CD

Assembly

-CD

:onnector. Zebra Strip
Nindow. LCD

)l

-

-

-

-

68/D3

R&H

-

­7

-

-

-

-

-

RH-170

CA-1 5

-

-

-

-

DD-25
CS-376.2
30195A

MODELS 135,176

REPLACEABLE PARTS

TABLE 6-5 CONTINUED

Circuir

D&g.

BAlOl
Cl01
Cl02

Cl03

Cl04
Cl05
Cl06
Cl07

Cl08
Cl09

Cl10
3111
3112
3113

:114
3115
3116
3117
3118
3119

:120
:121
:122
:t7101
IR102
:R103
:I?104
:fl105
ZR106
:ri107
:RloE
ZR109
:Rllo

Description

Gasket

SUDDOit.

I

Ta0e

25OuF. 25V. Alum

1 OuF. 16V. Alum
1 OluF. 16V. Alum
1 OuF. 16V. Alum
1 OuF. 16V. Alum

1 O@F. 16V. Alum

4,7uF. 25V. Alum

1uF. 5OV. Cer

1 O!JF. 16V. Alum

1uF. 50V. Cer
1uF. 5OV. Cer

1 op. 5ov. Cer

1 OuF. 16V. Alum
Z?OOP. 5oov. Cer D

5~. 1 OOOV. Cer D

15op. I ooov. Cer D
1 OpF. 16V. Alum
1 OuF. 16V. Alum

O&F. 500V. Cer D

~OlpF. 50V. Polycarb
,5P to 1 ZIP. 2ooov

1 50. 5ov. Cer D

Recttfier
Recftfter
ReCtltler
R.?ct,f,er
Rectifier
Aecrifier
Recftfier
Rect,f,er

Rectlfler
Low Voltage Reference
lzenerl

LCD

Sch.

Location

-

-

I I

-

G2
G2

G2
G2
G2
G2
Gl
Fl

Fl

63
El

El
El
83

El
El

El
Dl
01
Cl

A5

62
62

G2
G2
H2
Dl
Cl
El

El
A3
A3

Fl

PC-&i

Item NI

Locaric.. ____ -““, J,

3182

4/B2

5/B2

6/B2

7/B2
E/82
g/c2

lO/B3

11183

i 2/A3
13/A3
14/B4
15/B3

16/C3
17/B4

18185
19/B4
2O/B4

21184
22/86

23/C2
24/C2

27/B2
28/82

29/A3
3O/B4
31/B4
32184
33/84
34/B5
35/B5

36/C2

RIG

NIC
NIC
NIC
NIC
NIC
NIC

ERI

NIC
ERI

ERI

NIC

CLB
CLB
NIC
NIC
ERI

ECI
EFJ

CLB
T-l
T-l
MOT
T-I

T-l
T-i
T-I
MOT
MOT
MOT

HC-4B-250

25.8P
lGU,AlODT
16ULAlODT
16ULAlODT

16ULAlODT
16UlAlODT
25UlA4

R7D-T

8121.050

625.104M
16ULAlODT

8121-050

625.104M

8121-050

625.104~

SRlSIA

1 OOKAa
16UlA10DT

DD-050
DD-151

lGKU61ODK

16KUElODK
8 1 I -OOO­z5u
62581~103
273~1.1
DTZlA5

lN914
lN914
1 N4006
IN914
lN914
IN914
lN914
I N4006

1 N4006

LM385Z

r

I

-

30382A
EA. 14

C-314-250

c-313-x
C.313~!L,
C.313~12
c-313.;o
c-313-10

c-314-4 7
C-237. !
c-313-10

C-237. 1

C-237. ?
C-237-100

c-313.16
c-22-2ioo~
C-64-50
C-64-130~
C-321-10
C-321-10
C-316-02

C-215~01
C-183-1 50

c-291-1 50
RF-28

RF-28
RF-38
RF-28
RF-28
RF-28

RF-28
RF-38
RF-38
30985A

1101
1101
I101

1102
1103

1104
1105

75A. Fuse. 250V Max
Transistor. NPN
Thfck Film

200R. 10%. 3/4w. Pot

2.15K. 1%. l/lOW. MtF

8.98K. 1%. l/lOW. MtF

Thtck Film

A3

83

SEV
Fl

Fl
F2
SEV

56/C2
60/82

61/C2
62/C2

63/C2
64/83

L-F
NAT
Epltek

BRN

ACI
AC

Eplrek

312 750
2N3904

TF-127
3006P- 1
201
CR
CR

TF~l3,

FU-14
TG-47
TF-:28

RP-89-200
R-263~2 15K

A-263~8 98K

TF-131

REPLACEABLE PARTS

MODELS 135/176

TABLE 6-5 CONTINUED

Circuit

Desig. Description

RI06 3.3K. 5%.

R107
I7108 9.96K. .l%. 1/6W. MtF El 67104

RlOS

RllO
Rlll

Rl12
R113

R114
R115
R116
R117

*Part of a set selected at the factory. (30985A) (The set includes CR1 10 and RI 17.)
RTlOl A4
SlOl Switch HZ 80/A2

s102
s103

UlOl LCD. Counter
u102 CMOS. Low PowerOPAMP
u103
u104 Linear OP AMP El B7/B4
u105 JFET OP AMP Dl BE/B4

-

21.93K. .l%. 1/6W. MfF
2oo~.ilo%. Pot

1 OOK. 10%. 1 W. Carb
1 OOK. 10%. Pot

9.99. 1%. 1/8W. MtF
50K. 10%. Pot

.01a .5%. lW.Ww
470K. 10%. 1W. Carb A5

Thick Film SEV 75/C2

’ 1%. 1 /BW. MtF

Switch. Rotary
Switch. Rotary

CMOS.

Test Lead Kit

1/4W. Carb El 65184

Voltage Converter

Cover. Eatterv
Cover. Fuse

Sch.

Location

El 66/B4
01 68/65
Cl

D2

A3
82

A2 73185

F’ 76/C,

SEV
SEV 82/C4

G3 84/B 1
Fl 85/62

G2

Item No./

Location

69/B5
70/85

71/B5
72/B5

74/06

78/B3

Bl/C3

86182

- -

-

-

-

-

Mfr.

Code

A-B

CE

ACI CR

ERN 3366H.l-

A-B

BRN

ACI
BRN 3386~.i-

DLE
IRC
CAD TF-126

- -

CNW
CLB
CLB

INT

INT

INT

NAT

T-l

201
CE
3386H-l-l

104
CR

103

ICML7224
ICL7621
ICL766OCPA
LM308

TLOGlCP

-

-

-

PC-Board

Mfg.

Desig.

GB; W

-

-

-

-

-

-

Keithley
Part No.

fl-76-3.3~
R-179.21.93K
Rl-79-S.SBK
RP-1 1 l-200

R-2-100K
RP-1 11-IOOK

R-179-9.99
RP-1 1 I-50K

R-280-.01

A-2-470K

TF-126

R-88-’

RT-7

SW-41 7
SW-432
SW-433

IC-286
IC-286
IC-287
c-99
IC-227

CA-B

30186C
30187C

6-8

MODELS 1351176

REPLACEABLE PARTS

REPLACEABLE PARTS

MODELS 1351176

MODELS 1351176

REPLACEABLE PARTS

REPLACEABLE PARTS

MODELS 135/176

6-12

MODELS 1351176

REPLACEABLE PARTS

REPLACEABLE PARTS

MODELS 135/176

:

P t

t-7 I

6-14

,

\,

~.,)

‘X

-CD,

:

1