Tektronix 7057A Instruction Manual

Model 7057A Thermocouple Scanner Card Instruction Manual

Contains Operating and Servicing Information
Publication Date: January 1992 Document Number: 7057A-901-01 Rev. D
LIMITATION OF WARRANTY

Safety Precautions

The following safety precautioos should be obsewed before using this product and any asno­ciated instrumcntatioo. Although some inrtromeots and accessories woold nonnally bo used with nowhazardous voltages, there arc situations wberc hazardous conditions may be present.
This product is intended for use by qualified personnel who rccogoiu: shock hazards and are familiar with tbc safety pnxaotions rcqoircd to avoid possible injuly. Read lbe operating it]­formation carefully before using the product.
‘The types of product users arc: Kesponsiblc body is tbe iodividunl or group responsible for the USC sod owinleoaoce of
equipment, for ensuring tlnt the equipment ia operated within its spccilications and operat­ing limits, and for ensuring that operators are adequately trained.
Operators use the product for its intended function. Tbey most be trained in electrical safety procedures and proper use of the iostrument. ‘lhey most be protected from electric shock and ~onmt with hazardous live circuits.
Maintenance personnel perform mutioe procedures oo the product to keep it operadog, for example, setting the hoc voltage or replacing consumable materials. Maintenance proccdurcs am dcacribed in the manual. The procedures explicitly state if the operator ~nay perform them. Othcrwisc, they should be performed only by senice pcnonoel.
Service personnel are trained to work on live circuits, sod perfoonn safe installations sod re­pairs of products. Ooly properly trained setvice personocl may perform installation and scr­vice procedures.
Exercise extreme caution whco a shock hazard is present. Lethal voltage may be present on cable coonector jacks or test fixtures. 111~ American National Standards lostitute (ANSI) stam that a shock hazard exists wheo voltage levels greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring.
Users of this product must be protected fmm electric shock at all timer. The responsible body must eosum thtat wets aw pwented a.cce~s aod/orinsulatcd from every connection point. lo some cases, conoectiuns most be exposed to potential buman cootact. Product usa io these circuo­stances must be trained to protect themselves from the risk of electric shock. If the circuit is ca­pable of operating at or abovc 1wO volts, no conductive part of the circuit may be exposed.
AY described in the Ioteroational Electratechnical Commission (IEC) Standard IEC 664, dig­ital multimcter measuring circuits (e.g., Keifhley Models 175A, 199, 2OOQ,2COl, 2002, and
2010) are Installation Category II. All other instruments signal tennioals are Installation Cat­egory I and must oat be conoected to mains.
Do not conoect switching cards directly to unlimited power circuits. They are inlendcd to bc used with impedance limited sources. NEVER connect switching cards directly to AC mains. Wheo conoccting sources to switching cards. iostall protective devices to limit fault current sod voltage to tbc card.
Before operating ao instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks bcforc each oso.
For maximum safety, do not touch the product, test cables, or any other instrumcots while pow­er is applied to the circuit under test. ALWAYS remove power from the entire test system sod dischuge soy capxitors before: coooccting or disconnecting cables or jumpers, installing 01
removing switching cards. or making iotemtil chaogcs, socb as installing or nzmoviog jumpers. Vu not touch soy object that could provide a con-cot path to tbc common side of the circuit
under test or power line (eatth) ground. Always make measurements witb dry hands while standing oo a dly, insulated surface capable of withstanding tbc voltage bciog measured.
The instrument and accessories most be used in accordance with its specifications and op­eratiog iostructioos or tbe safety of the equipment may be impaired.
Do not exceed the maximum signal levels of the instruments and accessories. as defined in tbe speciticationr sod operatiog information, and es show on the instrument or test fixture panels, or switcbiog cant.
When fores are used in a product, replace with same type sod rntiog forcootioued pmtectioo against fire hazard.
Cbassir connections must only be used as shield coooectioos for me~suriog circoits, NOT as safety eaflh ground connections.
If you are using II test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires tbe we of a lid interlock.
1ra@
screw is present, connect it to safety earth ground uaiog the wire recommended in
the user documentation.
The ! symbol on an iostroment indicates that the user should refer to the operating ill-
n
stmctions located io tbc manual.
The h
symbol on al iostmment shows that it CNI source or IIICRIIUII: loo0 volts or more, ill­eluding the combined etTect of normal ad common mode voltages. Use stiuldarrl safety precau­lions to avoid pcrsooal cootect with these voltages.
TIE WARNING beading in A manual enplaios dangers that might result in personal injury or death. Always read the associated information wy carefully hcfore ptxformiog the indicated
pC"CCdU~C.
The CAUTION beading in a manual explains hazards that could damage the instrument. Such damage may invalidate the warrmty.
lostrumcntatioo and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
To maintain pmtcctioo from electric shock and ftre, replacement components in mains cir­coils, including the power transfouner, test leads, and ioput jacks, must he purchased from Keithley Instruments. Standard fuses, with applicable national safety appmvals, may be used
if the ratiog sod type are the same. Other components that are not safety r&ted may hc por-
chased from other suppliers as long as they are equivalent to tbe original component. (Note that selected parts should be purchased only through Keithley Iostmmcnts to maiotain acco­racy sod fonctiooality of the product.) If you we unsure about the applicability of a replacc­ment component, call a Keithlcy Instruments office for information.
To clean an instrument. use a damp cloth or mild, water based cleaner. Clean the exterior of the instrument only. Do not apply cleaner directly tb the instrument or allow liquids to enter or spill on the instrument. Products that consist of a circuit hoard with no case or cbas­sis (e.g., data acquisition board for installation into a computer) should neverrequire clean­ing if handled according to instructiuns. If the board becomes contaminated sod operation
is affected. the hoard should he returned to the factory for proper cleaninglserviciog.
tie”. 2rB

SPECIFICATIONS

CHANNELS PER CARD: 9 plus temperature reference. CONTACT CONFIGURATION: 2 Pole Form A with common guard.
CONNECTOR TYPE: Screw terminals in isothermal block, No. 18 AWG wire
maximum.
RELAY DRIVE CURRENT: 12mA lper relay).
TEMPERATURE OFFSET: i0.05°C maximum from HI to LO of any input or be-
tween any two adjacent channels in one column on the isothermal block. * O.lOC maximum between an two ferminals on the isothermal block. Maximum addi-
tional dynamic offset J ue fo 10°C step chsngo in environment: *O.l°C after one
hour settling.
TEMPERATURE REFERENCE: Thermistor in a linearized bridge.
REFERENCE OUTPUT: - ,m”,°C, ,Om” at +3O”CI. REFERENCE ACCURACY: f0.2S°C ,,O’=C to 35OC,, +0.5OC
WARM UP TIME: 1 Hour to rated accuracy.
CONTACT OFFSET VOLTAGE: I,,“. ACTUATION TIME: < 5ms, exclusive of mainframe. CONTACT LIFE: > lo* cbs”res. CONTACT RESISTANCE: < 2n (<O.,O inidall. C”ANNEL ISOLATION: ‘109O. 1OpF. INPUT ISOLATION: a 10’R. 15OpF. COMMON MODE VOLTAGE: 200” peak. ENVIRONMENT, SPECIFIED: ,O’=C to 35°C. up to 70% R.H. ENWRONMENTAL, OPERATING: O°C to 50°C, up to 35OC at 70% R.H.
ENVIRONMENTAL. STORAGE: -25OC to +55”C. DIMENSIONS, WEIGHT: 32mm high x 114mm wide x 272mm long I1 %*’ x
4%“~ 10%“) net weight 0.54kg Illb. 5,502.).
Signaf Level: 42”. 1DDmA. 2VA maximum Inon-inductive load only).
,O”C to 10% and 35°C to 60°Cl.

TABLE OF CONTENTS

SECTION l-GENERAL INFORMATION Introduction
1.1 Warranty Information
1.2 ManualAddenda
1.3
Safety Symbols and Terms
1.4 SECTION Z-OPERATION
Introduction
Wiring
Operating Considerations,,
2.3
Operating Hints
2.4
Thermocouple Measurement Considerations,
2.5
Measurement Procedure
2.6
SwitchTerminology.. .....................................
2.7
SECTION 3-SERVICING INFORMATION Calibration Procedure.,
3.1 Calibration Procedures
3.2
Test of Calibration
3.3 Channel Isolation,,
3.4
3.5
Input Isolation, Common Mode SECTION 4-REPLACEABLE PARTS
introduction,
4.1 ReplaceableParts
4.2 Ordering Information
4.3
FactoryService ..........................................
4.4
4.5
Component Layout and Schematic Diagram
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LIST OF FIGURES

Typical Thermocouple Connections
:
Plug-In Board Assembly.
3
Using GUARD Connection
4
Typical Multiple Channel Analog Connections. Typical Thermocouple Measurements
Switch Terminology
ii
Chsnnel~lsolation Test Setup Common Mode Isolation Test Setup
;
Model 7057A. Component Location Drawing
9
Model 7057A. Schematic Diagram
10
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21
;1 21 22
23
ii 23
23
3 4 5 5 6
7 22 22 26 27

LIST OF TABLES

Summary of Temperature Measurement Procedure
:
NBS Quwtic Coefficients for Types S, R, B, E, J, K and T Recommended Test Equipment.
3 4
Model 7057A Rep!aceab!e parts .:
5
Model 7057A Replaceable Parts ,Mec”a”~ca,, 24
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.. : .,:
.... :
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................
7
......
2: 23
SECTION 1
GENERAL INFORMATION

1.1 INTRODUCTION

The Model 7057A is a thermocouple scanner card which is field-installable in an appropriate scanner mainframe (e.g. Model 7051. Since it combines the func­tions of a thermocouple scanner and uniform temperature reference, it is especially useful for scanning thermocouples. The input terminals aie HI0 alloy­copper set in an isothermal block to minimize temperature differences. A ther­mistor sensor within the isothermal block is used with a bridge network located on the Model 7057A to give an indication of the temperature reference or cold junction. The temperature of the heat sink is used to calculate the corrected thermocouple output. The output voltages of each thermocouple must be con­verted to temperature PC or OF) using appropriate thermocouple tables or polynomial equations. In addition any channel may be used for monitoring low­level signals. The Model 7057A uses Z-pole form A contacts for witching of signals up to 35V peak or IOOmA peak. Input and output connections 818 made through the rear panel of the scanner mainframe using #4 screw terminals on the
Model 7057A.

1.2 WARRANTY INFORMATION

Warranty information is stated on the inside front cover of the manual. If there is
a need for service, contact the Keithley representative or authorized repair facility in your area. Check the back cover of this manual for addresses. The service
form supplied at the end of this manual should be used to provide the repair
facility with adequate information concerning any difficulty.

1.3 MANUAL ADDENDA

Any improvements or changes to this manual will be explained on an addendum included with this manual.

1.4 SAFETY SYMBOLS AND TERMS

The symbol
i;;i;TbolN
The WARNING used in this manual explains dangers that could result in
personal injury or death. The CAUTION used in this manual explains hazards that could damage the
instrument.
denotes that the user should refer to the operating instruc-
A
denotes that a high voltage may be present on the ter-
1
SECTION 2
OPERATION

2.1 INTRODUCTION

This section provides information needed to use the Model 7057A with an *ppropriate scanner mainframe.

2.2 WIRING AND INSTALLATION

1. Wiring Configuration-The Model 7057A has a Z-pole switching configura­tion. It may be used to connect one of nine signals to the output. The tenth scanner position (Channel 1) is used to monitor the temperature of the input terminals with a thermistor bridge. Bridge power is derived from a non-
isolated internal supply with jumper provisions for an external isolated supply. A. lnwt and output connections are made to the screw terminals shown in
Fi& 1.
8. Signal path resistance, including both poles of a channel relay, is typically less than 1.4?, less than 2Q et end of life.
C. A guard surrounds 811 signal paths and is connected to the heat sink
surrounding the input terminals. Connection to the guard is made at the isothermal block.
2. Installation-Refer to the scanner mainframe instruction manual for scanner instructions.
I
I-==
Figure 1. Typical Thermocouple Connections.
3

2.3 OPERATING CONSIDERATIONS

1. Signal Level-IOV peak, 1OmA peak with a resistive load for expected life. Maximum peak instantaneous rating is 35V.
2. Contact Potential (Laboratory Environment)-Less than I$/ from input to output when copper wires are used.
3. Isolation-Guarded interchannel resitanceis nominally@!?. Guarded cap*­citance is less than 1OOpF between any two channels.
4. Maximum Levels-A 2OOV peak between channels or from channel to guard or mainframe (digital) common.
5. Operating Environment-OQC-50°C, up to 35°C at 70% relative humidity.

2.4 OPERATING HINTS

1. The clamp-type screw terminals will accept #I8 to #36 AWG (0.044 to
0.005 inch) wire. Figure 2 shows the mechanical features of the Model 7057A which prevent lead movement after the board is wired.
Figure 2. Plug-h Board Assembly
2. Thermal offset on any given channel is typically repeatable to within a few hundred nanovolts each time the channel is selected. That is, every time a channel is selected and allowed to stabilize for a period of time, the channel will exhibit the same thermal offset to within a few hundred nanovolts. This offset may be accounted for in the measurement and subtracted from each
reading, to obtain a more precise measurement.
3. To effectively eliminate error voltages produced by leakage current, the GUARD terminal should be connected to the reference connection on the channel which is most sensitive to error (that is, the one which has the lowest source voltage versus the highest resistance). For instance. two sources are connected to the Model 7057A; one having an equivalent source voltage of IV with a series resistance of IOOkR and the other having a source voltage of .lV with a lkn series resistance. The lOOka source resistance will develop 100 times the error voltage as the lkn Knwze resistance. Its source voltage however, is only 10 times as great. which means that the percentage error is 10 times as large on the lV/lOOkn chan-
4
nel. The GUARD would therefore be connected to the reference point of this channel. ISee Figure 3).
Figure 3. Using GUARD Connection
4. The relay switching time includes a 9&s time interval between releases end operate conditions. The actuation time is less than 5msec.
5. Reactances in the system cause transients during switching.
6. For scanner systems using two or more plug-in boards output HI and LO on
all Model 7057A plug-in boards should be made using continuous copper wires. This ensures that the number of copper-to-copper junctions is at a minimum and therefore unnecessary thermal effects are avoided. Figure 4 shows the method of continuous board-to-board connections.
Figure 4. Typical Multiple-Channel Analog Connections

2.5 THERMOCOUPLE MEASUREMENT CONSIDERATIONS

A thermocouple is B junction formed between two dissimilar metals. If the
junction temperature is T, a voltage E, will be developed between leads A and
B. When connected to B voltmeter two more junctions are formed with meter
terminals, which are usually copper as shown in Figure 5.
Figure 5. Typical Thermocouple Measurement
The voltage measured by the voltmeter is proponional to the difference be­tween temperature T, and T2. To determine T,, T2 the thermoelectric proper­ties of the thermocouple are needed. Data is available to determine the voltage versus temperature relationship based on a reference temperature IT*) of 0°C. Thus, if the thermocouple-to-copper junctions were maintained at O°C it would be possible to determine T, directly by referring to thermocouple reference tables*, which give temperature as a function of the meter reading V,. If these junctions are different from 0°C a voltage E2 will be introduced, where V, = E,-E,.

2.6 MEASUREMENT PROCEDURE

In the Model 7057A the reference temperatwre T is measured by a dual ther­mistor in a bridge circuit. The temperature of a thermocouple connected to Channels 2 through 10 is determined by the following procedure:
1. Measure the voltage for the reference junction V and calculate Tz. T2 =
30-w, x 1031.
2. Determine the reference junction voltage, E2, either from thermocouple reference tables’ or by the calculation**:
5 = a0 + A, T + a,p + aaT + a,,+ where T = T2 as determined in step 1 above. Q is expressed in microvolts. The constant a0 through a4 are a
function of the thermocouple type connected to the channel. The coeff-
CiWntS, aO, a,, a?, a3 and a4 are dependent on the thermocouple type and
temperature range under consideration.
3. Measure the thermocouple voltage V, at the channel output. Convert to microvolts.
4. Add b to V, to determine E,. E, =V, +E, (where V, is expressed in microvoltsl.
5. Determine the thermocouple temperature, T,, either from thermocouple reference tables* or by calculation**:
TI = a, + %EI. + %E12r + e,E? + %EI+ (where E, is expressed in microvoltsl.
6. For example, consider a type J iron-constantan thermocouple at 300°C (T,I. The reference junction temperature will be 6 to 10°C above ambient, say 36% IT2).
A. The bridge output ichannel II will be -.006V. Since the bridge output is
zero when T, = 30°C this indicates T2 = 36OC.
B. Using NBS Monograph 125 to determine the reference voltage for a type
J thermocouple gives b 4 1649,O@V. Using the most accurate quark
approximation formula (Table 21 for this range gives lB49.085@, C. The voltage at Channel 1, which is V,, will be 14476,OpV. IV, = E, -b). D. Add 6 to V, and get E, = 16325.0@,
6
E. Using Table A6.2.1 to find the thermocouple temperature gives
300.00°C. Using the formula (Table 2) gives 299.995°C.
* Thermocouple Reference Tables, Based on the IPTS-66 National Bureau
Standards Monograph 125. (SD Catalog No. C13.44~1251
** See also Table 2 which summarizes the quartic coefficients.
Table 1. Summary of Temperature Measurement Procedure
Quantity
channel output V,. Determine equivalent
V2
bLSl
Tz = 30-I!!, x 103)
Measured desired
Calculate correction
VI
(volts)
F
lCalcuiat~~olt.age E,. )
Calculate equivalent temperature TV.

2.7 SWITCH TERMINOLOGY

Throughout this manual the terminology Form A is used. The term Form A is
used in switch terminology and is described as follows:
1. Form A is simply a single pole normally open ISPNOI switch (refer to Figure 6). A Z-pole switch normally open is classified as 2 Form A.
2. Form B is similar to Form A except that its contacts are normally closed (refer to Figure 61. A Z-pole switch normally closed is classified as a 2 Form B.
3. Form C is shown in Figure 6 as a single pole double throw switch. It could also be a multipole switch such as a Z-pole which would be classified as a 2
-- 1 E, = E2 + V,.x-lO-” 1 mic~v,lts 1
T, = a, + a,E, + a,P, +
*Pl + Wl
T, IW
Figure 6. Switch Terminology
7
Reference Junction
1
16% to 176%
Correction
” tn m
Table 2. NBS Quartic Coefficients for Types S. R. B. E. J. K. and T.
Argument hp.
a0
=I
=2
Argument EXP. Arg”me”t Exp. Arg”ment EXP.
5.5439639
5.9791m
6.2516%!3
6.5554!232 Ma34421
8.7228147
9.5827994
9.4531354
2.9873073
3.4129348
6.4091373
3.9952876 *.co4320*
1.3532278
5.3994446 +o 1
I.2467754 -2
a3
Argument Exp.
a4
Exact-Approx.
Error
Range ILNV)
c
4.1137317 +1
4.4507790 +1
4.1670535 + 1
-3.0938374 +1 z!2zm7 +7
1.3866867 +2
1.3923740 +2
4.6133695 +3
2.3131446 +4
I
-2.0241757 -5 -2.0241757 -5
-m349c6, -5 -m349c6, -5
-9.cl763455 -6 -9.cl763455 -6
-7.0073775 -6 -7.0073775 -6
-6.319500, -6 -6.319500, -6
-1.8612979 -6 -1.8612979 -6
-,.33496,, -6 -,.33496,, -6
- I .6,62,80 - I .6,62,80 - 6 - 6
-4.9,94442 -6 -4.9,94442 -6
-3.2873314 -6 -3.2873314 -6
4.659nc8 -8 4.659nc8 -8
7.7266682 -8 7.7266682 -8
1.032002 -4 1.032002 -4
4.934,196 -4 4.934,196 -4
4rgumem Exp.
80
Zrgumenf Ex*.
a1
-4.0674108 +*
-5.mm84 +*
-5.4505828 +*
1.6618169 +3
1.5132838 +3
2.4m3703 +3
1.5787334 +3
-7.1904948 +4
8.8532076 14
5.4295008 +o
5.7622558 +o
6.1429772 +!I
6.4615269 +o
6.596212u +o
8.7490234 +o
9.673111, +o
9.5942872 +o
2.3048626 +O *.795%247 +o
4.1604579 -1 *.6321,44 +o
1.94423a3 +*
- ,.5014129 +*
1.1446885 -2
9.2715271 -3
7.1515857 -3
5.7010917 -3
5.1559203 -3
1.7115155 -3
-2.6994046 -4
-1.2813352 -4
8.7635426 -3
8.1571403 -3
1.0549178 -2
8.31co314 -3
- 1.7913090 - 1
9.5376167 -2
-1.1295306 -5
-7.1346883 -6
-3.7639447 -6
-1.8683292 -6
-1.2385309 -6
7.5039035 -7
2.5536988 -6
2.4468512 -6
-2.3016?318 -6
-1.9701159 -6
-3.0383621 -6
-2.0332036 -6
7.9264764 -6
-1.6644901 -5
-0.01 to +o.o,
5.w2w96 -9
2.5877454 -9
9.6963832 -10
2.3636365 -10
1.m3.27643 -11 1.m3.27643 -11
-3.oo96280 -10 -3.oo96280 -10
-8.9155191
-8.915549,
-8.6286758 -10
7.4284923 -11
6.5568964 -12
1.8540516 -10
1.6260416 -11
- 1.3167245 -8
-8.3062870 - 10 -8.3062870 - 10
- 10
- 10
-7 to 16
- 16 to 12
-35to25
-551036
7
-661036
- .4 to .5
-1~7 to 1.6
-2.1 to 1.8
- .05 to .05
- .05 to .05
- 45 to .05
- .05 to .05
-1.0 to 1.3 .05 to .05
,rg"ment Exp.
=0
Argument Exp.
a2
Argument Exp.
84
4.5509556 +1
4.9160016 +1
4.8343651 +1
-4.1134469 10
3.7487318 +1
8.0559850 +1
1.4180146 +3
3.176!3333 +3
1.2683437 +4
1.6251434 -1
1.5239494 -1
1.4441607 -1
1.3344190 -1
1.3752efj? -1
1.12ed875 -1
1.1054689 -1
1.1098270 -1
1.2738464 -1
1.1515zc4 -1
1.0442877 -1
9.0181346 -2
-5.m2431 -1
- 2.6747958 + 0
-2.0454379 -5
-1.3755675 -5
-9.5014952 -6
-7.4485484 -6
-6.7661171 -6
-2.86ces78 -6
-2.3559046 -6
-2.4353s9o -6
-4.3132296 -6
-2.9827002 -6
-1.9Enm -6
-7.4069329 -7
5.6190639 -5
2.2334214 -4
2.5404935 -9
1.2610922 -9
6.2073358 -10
3.8266182 -10
3.M2c473 -10
8.6173702 - 11
3.9276246 -11
-1.1767904 -13
-4.4281251 - 14
-1.9622497 -14
-7.4617277 -15
-5.4254672 -15
-1.1440038 -15
3.33-4 -16
1.8172612 -16
-1Ea3798 -15
-3.78Gss57 -16
2.4513433 -16
9.4290495 -16
3.0369250 -14
1.0882779 -13
-13to3
-4to7
-6 to 10
-7to13
-7 to 14
-.0tto.o4
-.08tom
-.lOfO .12
- .m* to .x3*
-.Oll to ,011
-.x05 to .wo5 .wo5 to .ooo5
-.ll to .I8
.ccm to .a307
a0
4rg”ment EXP.
=I =*
PIrgument EXp. Argument Exp.
Argument Exp.
a3
1.3740347 +1
-2.5321108 +1
-1.1708354 +*
-9.8446269 +2
1.3702395 + 3
~4.76445Sl +*
- 6.4mas29
‘Quadratic. cubic. and quark approximations f E=ag+alT+a*T*+a3T3+aqT4where E is in
+ 2
- I.3749133
-3.2914888
-9.9736579
3.smx94
3.367OEsS
~f!Eiy~~
7e dafa as a function Of temperat”le ,Y :rwolfs and T is in degrees Celsius.
- 1 6.3446673
-1 5.9766638
-2 5.4976533
-1 4.5539656 +o 8.2282215
-3
-3
-3
-3
-4
-5.6339756 -7
-5.9983692 -7 -9.7c41131 -11 -.,*to.*o
- 5.7165679 7 ~3.3057S24 -7 -2.w18428 10
-9.1094186 -8 -2.8098361 -10
-8.0141311 -7 - 2.7203972 - 1, - .05 fO .05
-3.6623964 -7 -3.6S6Slcc -10 -2.0 fo 1.8
3.6623964 -7 -3.69691cc -10 -2.010 1.8 *.‘lm1224 -6
3.W5686 -6 -9.4548852 -10 .05 fO .05
2.2417410 -6 ~7.6471224 10
2.4305578 -6 -8.1518033 -10 - .05 to .05
-1.2267180 -6
1 selecied temperat”re ranges. me expansion is 0‘ the form
-1.1808558 -10 -22f0.14
-1.0818193 -10 -.,m,.o
-4to5
-*to9
-7.7901142 -10 .05 ro .05
- $5 fO .05
0.01 fO +o.o,
80
E,,W
Range
WV1
EX*Ct-App,OX.
,rgument Ex
-5.7447033 -4
7.2874oE6 -1
5.7822214 -1
4.SS2Slrn -1
1.8946288 4
2.0949015 4
2.2394664 i
3.2188156 4
3.44,5x4 t
4.6255054 -1
3.ux.6136 -1
2.7222162 -1
2.4988761 -1
1.8282378 -1
1.7031473 - 1
1.5828913 -1
1.4979551 - 1
-3.177193, -4
-1.6039309 -4
-1.0349686 -4
-8.2176262 -5
-6.81oo680 -5 ~3.6330332 -5
-2.71@33,2 -5
-1.1561743 -5
-8.9696912 -6
-7.0050689 -6 ~6.n762S3 -6
-301075
-35row
-45 to 110
-5otom
-50 TO 130
-.09fO,.O
-3to3
-5to5
-.cmro.o03
-.0*5 to .o*o
- .W, 10 .w,
- ,031 to .Wl
1
n is Of the form
*0
Argwnent Exp.
*3 *3
\rgument hp. \rgument hp.
aq
*rgument Exp.
‘Cluadr*tic, cubic. and qu ‘Cluadr*tic, cubic. and qu E=ar,+a,T+a*T2+,3T: E=ar,+a,T+a*T2+,3T:
-8.5384268 +2
-1.383%33 +3
-5.1503130 +4
5.9287179 +1 5.9287179 +1 7.0983783 -2
5.6754764 +1 5.6754764 +1 5.7443085 -2
5.8943714 +1 5.8943714 +1 5.611850, -5
5.8318736 +1 5.8318736 +1 5.4292960 -2
5.m7691 +1 5.m7691 +1 5.3761106 -2
5.8734537 +1 5.8734537 +1
6.5022W +1 6.5022W +1
6.7*111*6 fl 6.7*111*6 fl 3.1669230 -2
-1.6691278 +2 -1.6691278 +2 4.1877018 -1
5.8637565 +1 p4.67*w25 -2
5.0763!?31 -2
3.4354900 -2
5.*421&u -5 5.*421&u -5
-5.GmmTn2 -5 -5.GmmTn2 -5
-5.9506584 -5 -5.9506584 -5
-5.6286941 -5 -5.6286941 -5
-5.2870696 -5 -5.2870696 -5
-4.7621793 -5 -4.7621793 -5
-2.9763494 -5 -2.9763494 -5
-2.9237913 -5 -2.9237913 -5
-3.1228607 -4 -3.1228607 -4
-1.443202 -6
3.8137875 -7
1.3960921 -7
2.2327737 -8
2.0825828 -8
1.5352840 -8
1.465!3118 -8
7.w39401 -9
8.1514671 -9
8.5283044 -8
-5to5
- .5 to .4
-6oto3n
-8704
-3ro4
-,8tol7
-2 to 2.5
- .03 to .03
-.06to.oE
- .12 70 + .24
I. Ouartic Equation
Error
Range
WV)
-2COt00
-mto76o
-MO to 12cm
-2oto5W 0 20 4cQ oto780
0t01200
4ooto760
4ooto12w
sooto760
780 to ,209
Reference Junction
Correction
0 to 50
t
-5.7831co5 +3 ,.,,2,3,, +3
-2.5724435 +4
3.9264982 +4
5.04cm743 +1
4.8xQ533 + 1
4.,052807 + 1
5.m +,
5.0452399 +1
5.12E8213 +1
5.5881877 +1
9.77l8!35 +1 ,.8%9x, +,
2.2151898 +2
-1.47850,7 +2
5.0373743 +1
a2
PIrgument hp.
3.Mo906) -2
3.269em2 -2
2.552650 -2
2.ax2596 -2
2.840913, -2
2.oo40854 -2
1.4207854 -2
-1.18E843n -1
5.3882730 -2
-4.041808, -1
3.647092, -1
3.01670,, -2
a3
Fwgumant 5xp.
-8.3493983 -5
-6.993603, -5
-2.2xl82s5 -5
-8.E&883o5 -5
-8.7558436 -5
-4.~ -5
3.1325181 -5
1.3184454 -4
-2.2171472 -5
4.2749984 -4
~2.7029305 -4
-7.4293513 -5
2.5174022 -7
5.,,,2,2!3 -8
7.1373907 -8
5.3587105 -8
5.ez8zo4a -8
3.281s4wJ -8
-1.5023,,0 -8
-4.8218788 -8
1.8445398 -10
1.6174242 -7
7.2113090 -8
a2
4rgument EXP.
a3
Argument Exp.
I 0 0 fO to ,200 400
Wuadratic. cubic. and q~artic approximation*
T=aO+alE+a2E2+a3E3+aqE4where E is in r
0t0760
4OOt07M1
403 fO ,203
6Wt07M1
700 to 1200
!3.2808351 +1
-1.1075293 +2
1.8020713 +2
-6.3828680 +2
1.8843850 -2
2.1155170 -2
2.1676850 -2
1.8745056 -2
1.8750953 -2
1.9323799 -2
1.8134974 -2
5.4483817 -3
2.8651303 -2
-4.5284199 -3
7.4068745 -2
- 3.3513149 -7
-2.1844454 -7 ~1.8094256 -7 ~I.8512600 -7
-1.03ca20 -7
1.2443!397 -11
3.9094347 -12
7.8771919 - 12
8.3681958 -12
3.7084018 -12
~2.5849263 -14
-1.5227150 -16
- 2.4303017
-1.1897222 -18
-1.328n568 -18
-5.1031937 -17
2.1141718 -17
9.9364476 - 17
-4.9012035 - 18
1.5521511 -18
- 17
IAlgUmenf
a2
Argument EXP.
83
Argm-“ant Exp.
1.3223524 +3
-3.6456236 +1
2.1326066 +3
-9.0373649 +2
-2.5972816 +3
3.9676618 +l
3.6478446 fl
3.6762217 +l
4.09B640 * 1
4.0961103 +1
3.9443859 +1
3.0191663 fl
3.8349319 +1
2.5608012 +1
4.0577145 +1
5.M75276 +1
3.1063356 -2
2.8266412 -2
2.4514587 -2
-3.2619221 -3
-1.5!%2510 -4
5.aJ53822 -3
2.76m912 -2
9.9993329 -3
3.7091744 -2
9.5092149 -3
- 1.4576419 -2
-9.16m895 -5
-1.14a8433 -4
-4.3@319%3 -5 S.FJl4137 -6
- 1.252RW.J - 5
-4.2015137 -6
-2.4734437 -5
-8.744446 -6
-3.3517324 -5
-1.0989249 -6
9.4854151 -6
3.0X+3626 -8
-2.8153447 -8
2.5127588 -8
-1.6912373 -9
3.2764725 - 8 I.3317059 -10
6.9798332 -9
1.7108618 -9
9.9607405 -9
-3.0753213 -9
-3.1,x779 -9
-1.1 fO 1.2
-.@3to.o+
-1mtom
-'25 to 45
-25to20
-60 to 110
-.9to1.4
-,2to,,
- .05 fO .o,
- .05 to .I3
- .05 to .05
-.ffito +.14
1 is of the form
a0
Argument EXP.
-r
a7
,rgu”lent Exp.
a2
Argument Exp.
a3
Argument EXP.
a4
*rgument Exp.
-270too
-200030
-2ootot?lm
-20t05CC 0 to ml
-2.4707112 t,
6.2300671 TO
-3.w30992 + 1
-3.1617495 CO
2.3615582 +2
1.2329875 -2
2.3763697 -2
2.8346886 -2
2.4363851 -2
2.4383246 -2
2.5132785 -2
2.3465633 -2
2.4655374 -2
3.1425797 -2
2.7115517 -2
1.1066277 -3
-1.4434305 -5
-2.4382217 -6
-5.8008526 -7
5.6206931 -8
9.7830251 - 9
-6.0883423 -8
-3.1332620 -7
-7.8788333 -8
-4.0935633 -7
-2.1941595 -7
8.2516607 -7
4.2824666
6.8203073
2.5720615 11
-3.8825620 -12
3.6276665 -12
5.5358209 -13
6.5075717 - 12
1.3266743 12
8.5462602 -12
4.6762626 - 12
-1.3558849 -11
9
4.2028679 - 13
10
-9.4854031 -14
-3.6813679 -16
3.9120208 17
-2.5756-W -16
9.3720918 18
-3.9663834 -17
1.5580541 -18
-5.5696636 -17
-2.9316611 -17
9.1638500 -17
I. Quartie Equafion
Argument
Exp.
3.9439319
+1
-27OtoO
-2cntoo
~200104m
Reference Junction
0 to 403
Correction
0 20 50
ä
3.8749356 +1
3.8621703 i-1
3.64@407 +1
3.8ml239 +1
=,
Argument Exp.
6.2407452 -2
4.5149603 -2
4.5433050 -2
4.6651731 -2
4.1277w -2
=*
-4.7753448 -5
8.0773568 -5
irgument Exp.
2.6846647 -7
-2.5773959 -8
1.4661300 -8
1.5999833 -8
=4
-0.04to t0.081
-9107
- .14 to .I3
-7 to 3.5
-9 to .9
I
Argument
4.3553379 -3
2.3837090 -2
2.6792411 -2
2.5661297~ -2
“Ouadratic. cubic. and qualfic approximarions fo fix data as a tuncti
T = a0 + al E + a2E2 + a3E3 + a4E4 where E is in mi~rovolts and T is in degrees Celsius
Argument EXP.
-2.0325426 -5 -5.4720813 -9
-2.9876839 -6
- 1.0370271 - 6 6.1330327 11
-6.195469 -7 2.2181644 - 11
=2
Argument Exp.
-7.1945810 10
=3
-5.0865527 13
-1.cc41943 -13
-1.39e8335 -15 ~3.5500900 -16
I
SECTION 3
SERVICING INFORMATION

3.1 RECOMMENDED TEST EQUIPMENT

The recommended test equipment for calibration and performance verification is given in Table 3. Test equipment other than recommended may be substituted if specifications at least equal those given in Table 3.
Table 3. Recommended Test Equipment
Itam Description
A 1 DMM
6 Voltage source C Electrometer
D Scanner Mainframe

3.2 CALIBRATION PROCEDURES

To calibrate the Model 7057A do the following procedure:
1. Remove the green wire on the Model 7057A.
2. Connect DMM across R104 l6.151kQ resistor).
3. Adjust RIO1 for 175.92mV fO.lmV.
4. Remove DMM and reconnect the green wire.

3.3 TEST OF CALIBRATION

Using RFL industries oil bath lor equivalentl, submerge thermistor Ion 7057Al with temperature standard measuring device (Thermometrics S-10 probe or equivalent) into the oil. Allow to stabilize and note the difference lat 30°C). The difference should be less than .2’C.

3.4 CHANNEL ISOLATION

A. This test ~measures the leakage resistance between two channels on the
board. One channel is to be open and the other closed. Set up the test cir­cuit shown in Figure 7.
B. Short the HI and LO connections of each channel on the Model 7057A. Do
not connect the channels together, just short the HI and LO terminals.
C. Set the Model 705 to the Channel mode, Channel 2 and the Step mode.
Set the electrometer to Amps and program the Model 230 to output 1OOV. Take the electrometer out of ZERO CHECK. Program the channel under test as open and other channels as closed.
D.Take the reading on the electrometer. The reading should be less than
1 x lo-6A. Using Ohm’s Law calculate the channel isolation. For example: R = E/I = IOOVll x lo-CA = 1 x lO%?. Due to the capacitance of the cir­cuit, the offset current may be high until the capacitance of the circuit is charged up. Wait until the readings settle out.
E. Manually scan through channels 2 through 10 repeating step C and D for
each channel.
Channel 1 is the temperature reference channel.
Specifications
I 1OuV resolution
1oov DC
IpA resolution
-
NOTE
21
Figure 7. Channel Isolation Test Sat Up

3.5 INPUT ISOLATION, COMMON MODE

A. This test measures the leakage resistance between signal lines and power
line ground. Set up the test circuit shown in Figure 8.
El. Short the input HI and LO terminals of each channel with a short piece of
solid copper wire. Do not connect the channels together, just short the HI and LO terminals.
C. Insert the Model 7057A into the mainframe and sea the Model 705 to the
Channel mode, Channel 2 and the Step mode.
D. Set the electrometer to Amps and program the Model 230 to output 1OOV.
Take the electrometer out of ZERO CHECK.
E. Take the reading on the electrometer. The reading should be less than
1 x lo-“A. Using Ohm’s Law calculate the isolation ileakaae resistance).
For example: R-=E/I = lOOVl1 x 10m5A = ~lO’n.- Due to the capacitance of the circuit, the offset current may be high until the capacitance is charged up. Wait until the readings settle out.
F. Manually scan Channels 2 through 10 repeating step D and E for each
channel.
22
Figure 8. Common Mode Isolation Test Setup
SECTION 4
REPLACEABLE PARTS

4.1 INTRODUCTION

This section contains replacement parts information, B schematic diagram and component layout for the Model 7057A.

4.2 REPLACEABLE PARTS

Parts are listed alpha-numerically in order of their circuit designation. Table 4 contains parts list information for the Model 7057A. Table 5 contains a mechanical parts list for the Model 7057A.

4.3 ORDERING INFORMATION

To place an order, or to obtain information concerning replacement parts,
contact your Keithley representative of the factory. See the inside front cover for addresses. When ordering include the following information:
1. Instrument Model Number
2. Instrument Serial Number
3. Part Description
4. Circuit Description (if applicable)
5. Keithley Part Number

4.4 FACTORY SERVICE

If the instrument is to be returned to the factory for service, please complete the service form which follows this section and return it with the instrument.

4.5 COMPONENT LAYOUT AND SCHEMATIC DIAGRAM

The component layout for the Model 7057A is shown in Figure 9, while
Figure 10 contains the Model 7057A schematic diagram.
Table 4. Modal 705JA Replaceable Parts
23
CkCUl
t
Deslg. Cl01
c102­Cl11
KlOl
K102 K103 K104 K105 K106
ix K109 KllO
RlOl R102
R103 R104 R105 R106
R107­R116
RTlOl
UlOl
Table 4. Model 7057A Replaceable Parts
Description
Capacitor, .l@, 5OOV, Polystyrene Capacitor, lOpF, 25V, Alummm
Electrolytic Relay, i Pole Form A
Relay, 2 Pole Form A Relay, 2 Pole Form A Relav. 2 Pole Form A R&i; 2 Pole Form A Relay, 2 Pole Form A Relay, 2 Pole Form A Relay, 2 Pole Form A Relay, 2 Pole Form A R&v. 2 Pole Form A
rot,‘ioon
Resistor, 77.77k, 0.02%, %W, Wirewound Resistor, 953.4n, O.OZ%, ‘/aW, Wirewound Resistor, 6.15kQ 0.02%, XW, Wirewound Resistor, 46.590, 0.02%, XW, Wirewound Resistor, 12k0, .l%, ‘/,W, Metal Resistor, 27OQ, 5%, ‘law, Composition
Thermistor Low Drift Voltage Reference, AD5803
Film
Ksithley Part No.
C-238-.1 c-314-10
RL-77
RL-77
E; RL-77 RL-77
;::g
RL-77 RL-77
Rl-97-100 R-260-77.77k
R-260-953.4 R-260-6.151k R-260-46.59 R-168-12k
R-76-270
RT-4
IC-151
Table 5. Model 7057A Replaceable Parts Mechanical
Description
Isothermal Block
Isothermal Block. Cover Clamp Assembl;, Upper a. Clamp, Upper
b. Strip, Rubber
Clamp Assembly, Lower a. Clamp Cable, Lower b. Stiip, Rubber
Handle (2 required)
Rivet (2 required)
Standoff (21 required)
#6-32 x 5116 Phillips Pan Head Screw
(2 required)
X6-32 x 1 inch Phillips Pan Head Screw
(2 required)
#6-32 x ‘X Phillips Pan Head Screw (Heat Sink)
(4 required)
#6-32 x J/4 Phillips Pan Head Screw (Heat Sink
Cover) (4 required)
#6-32 x 318 Phillips Pan Head Screw
Psrt Number
7057A-303 7057A-305 7055-303-06 7055-305 26621 7055-308 7055-307 26621 FA-119 FA-121 ST-139-7
Figure 9. Model 7057A Component Location Diagram
26
0
Y
Y
0
m
3 I; a
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