Keithley 1792 User manual

INSTRUCTION MAdUAL
Models 1792,6422
IsolatedBCD Outputs
Keithley instruments, Inc.
28775 Aurora Road/Cleveland, Ohio 44139/[phone]

WARRANTY
Keithley Instruments, inc. warrants this product to be free from defects
in material and workmanship for a period of 1 year from date of ship-
ment. During the warranty period, we will, at our option, either repair
or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley represent-
ative, or contact Keithley headquarters in Cleveland, Ohio. You will be
given prompt assistance and return instructions. Send the instrument,
transportation prepaid, to the indicated service facility. Repairs will be
made and the instrument returned, transportation prepaid. Repaired
products are warranted for the balance of the original warranty period,
or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from unauthorized
modification or misuse of any product or part. This warranty also does
not apply to fuses, batteries, or damage from battery leakage.
This warranty is in lieu of all other warranties, expressed or implied, in-
cluding any implied warranty of merchantability or fitness for a par-
ticular use. Keithley Instruments, Inc. shall not be liable for any indirect,
special or consequential damages.
STATEMENT OF CALIBRATION
This instrument has been inspected and tested in accordance with
specifications published by Keithley Instruments, Inc.
The accuracy and calibration of this instrument are traceable to the
National Bureau of Standards through equipment which is calibrated at
planned intervals by comparison to certified standards maintained in
the Laboratories of Keithley Instruments, Inc.
KEITHLEY INSTRUMENTS, INC.
INSTRUMENT DIVISION / 28775 Aurora Road / Cleveland, Ohio 44139 / U.S.A. / [phone] / Telex: 98-5469
WEST GERMANY: Keithley Instruments GmbH / Heiglhofstr. 5 / 8000 Munchen 70 / [phone] / Telex: 52-l 2160
GREAT BRITAIN: Keithley Instruments, Ltd. I 1, Boulton Road I Reading, Berkshire RG 2 ONL / [phone]/88 /Telex: 84-7047
FRANCE: Keithley Instruments SARL / 2, Bis Rue Leon Blum / B.P. 60 / 91121 Palaiseau Cedex / (6) 011-51-55 I Telex: 600-933
NETHERLANDS: Keithley Instruments BV / Arkelsedijk 4 / Postbus 559 / 4200 AN Gorinchem I (0) 1830-25577 / Telex: 24-684
SWITZERLAND: Keithley Instruments SA I Kriesbachstr. 4 / 8600 Dubendorf I 01/821-94-44 / Telex: 57-536
AUSTRIA: Keithley Instruments Ges.m.b.H. / Doblinger Haupstr. 32 / 1190 Wien / 314 289 / Telex: 13-4500

MODELS 1792, 6422
I SOLATED BCD OUTPUTS
Copyright 1979, Keithley Instruments, Inc.
Third Printing, May 1981, Cleveland, Ohio U.S.A.
Document No. 30155, Rev. B

TABLE OF CONTENTS
SECTION TITLE PAGE
1. GENERAL INFORMATION ................... l-l
l-l. INTRODUCTION ...................... l-l
l-3. COHPATIBILITY. ..................... l-l
l-5. WARRANTY INFORMATION .................. l-l
l-7. CHANGE NOTICES ..................... l-l
l-9. SAFETY SYMBOLS ..................... l-l
l-11. SPECIFICATIONS ..................... l-l
2. INITAL PREPARATION ...................... 2-l
2-l. INTRODUCTION ...................... 2-l
2-3. UNPACKING AND INSPECTION ................ 2-l
2.5. PREPARATION FOR USE. .................. 2-l
2-7. MODEL 1792 INSTALLATION. ................ 2-3
2-9. Fidel 1792 Output Connections. ............ 2-3
2-11. IIODEL 6422 INSTALLATION. ................ 2-4
3. GPERATION ....................... .3-l
3-l. INTRODUCTION ...................... 3-l
3-3. OVERALL OPERATION. ................... 3-l
3-9. CIRCUIT DESCRIPTION. .................. 3-3
3-11. Control Circuitry. .................. 3-3
3-14 Switching Circuitry. ................. 3-4
3-16. Isolator Network ................... 3-4
3-18. Busy/Hold Circuit. .................. 3-4
3-20. Output Registers And Buffers ............. 3-5
3-22. DC-to-DC Converter .................. 3-5
3-24 TEST POINT DATA. .................... 3-5
3-26. SPECIAL HANDLING OF STATIC SENSITIVE DEVICES ...... 3-6
4. REPLACEMENTPARTS ................... 4-l
4-l. GENERAL. ........................ 4-l
4-3. ORDERING INFORMATION .................. 4-l
4-5. SCHEMATIC. ....................... 4-l
4-7. COM’ONENT LAYOUT .................... 4-l
I LLUSTRATI GNS
FIGURE TITLE PAGE
2-l Installation of Model 1792 ............... 2-2
2-2 Installation of Model 6422 ............... 2-5
3-1 Model 1792/6422 Block Diagram. ............... 3-l
3-2 Timing Diagram ..................... 3-2
3-3 Ring Counter and Gating. ................ 3-3
3-4 Busy/Hold Circuit. ................... 3-4

UODELS 1792, 6422
SECTION 1 GENERAL lNFGRMATI(%
GENERAL INFORMATION
l-l. I NTRODUCTION.
l-2. The Models 1792 and 6422 are isolated BCD
output options that convert displayed meter readings
to electrically isolated, latched, and buffered per-
al lel 8CD outputs. These can be appl ied to I ine
printers or other external data hand1 ing equipment.
Logic levels are TTL/DTL and CMOS compatible.
Output data includes sign and overrange signals. In
addition, a BUSY control I i ne indicates that the
meter is updating data. The trailing edge of this
signal is normally used to initiate a print or load
operation at the listening device. An input control
I ine (HOLD) al lows the listening device to inhibit
the update of output data. When this line is high,
the data update rate is the same as the meter
conversion rate, typically 2.5 readings/second.
Operating characteristics for the Models 6422 and
1792 are given in their respective Specification
Tables (Table l-l and l-2). Both options can be
either factory or field installed. Separate
installation procedures are provided in this manual,
because of the different mounting and output cabling
provisions of the options.
l-3. CGf+‘ATIBILITY.
l-4. The Model s 1792 and 6422 interface options
are compatible with the following Keithley
I nstr unents:
Model 6422
Model 642 Electrometer Serial Nunber 53402A and
above.
Mode I 1792
Model 179 DMFl Serial Nunber 20000 and above.
Model 179-20A DMFl all Serial Numbers.
Model 177 DMM Serial Nunber 14500 and above.
Model 480 Picoammeter Serial Nunber 12000 and
above. Note: First 3-l/2 digits at BCD auf-put
same as Model 480 display.
l-5. WARRANlY INFGRMATIOIJ.
l-6. The Warranty is given on the inside front
cover of this Instruction Manual. If there is a
need to exercise the warranty, contact the Keithley
Representative in your area to determine the proper
action to be taken. Keithley maintains service fa-
cilities in the United Kingdom and West Germany, as
well as in the United States. Check the inside
front cover of this Manual for addresses.
l-7. CHANGE NOTICES.
l-8. Improvements or changes to the equipment which
occur after printing of the Instruction Manual will
be explained on a Change Notice sheet attached to
the inside back cover.
l-9. SAFETY SYMOBCLS
l-10. Safety symobls used in thls manual are as
fol lows:
IM3oRTANT
The !
n symbol can be found in various places in
this manual. Careful ly read the associated CAU-
TION statements with regard to proper use and
handling of the equipment. Damage to the equip-
ment may occur if these precautions are ignored.
t
This symbol can be found In various places in
this manual. This symbol indicates those areas on
the equipment which are potential shock hazards.
Careful ly read the associated WARNING statements
with regard to proper use and hand1 Ing of the
equipment. Serious personal injury may result if
these precautions are ignored.
1-11. SPECIFICATIONS.
l-12. Detailed specifications for the Model 1792
and 6422 are given In Tables l-l and 1-2,
respectively.
l-l

GENERAL INFORMATION MODELS 1792, 6422
SPECIFICATIONS
TABLE I-1
SPECIFICATIONS, MODEL 1792 ISOLATED BCD OUTPUT
OUTPUTS : 4-l/2 digit parallel BCD, polarity,
overrange bit, busy.
BUSY: Low during output update (5Oms max).
OUTPUT UPDATE RATE: Same as meter conversion rate
(2.5 reading/second typical).
CONTROL: E inhibits subsequent output updates
when low.
LOGIC LEVELS: TTL/DTL and CMOS compatible.
Output High = 4.5V minimum while
sourcing lOOkA.
Low = 0.5V maximum while
sinking 3.2mA.
Control High = open or 4V minimum.
Low = .5V maximum while
sinking 1mA.
ISOLATION: All outputs and controls isolated from
meter up to 1400V peak, 105V*Hz.
(lOlO, ,ll40pf typ1
ENVIRONMENT: Operate 0 to 55”C, 0 to 805 RH.
Storage’ -25 to 7O’C.
OUTPUT CONNECTOR: 26 pin card edge, mates with
CS294-1 (3M 3462 or equivalent)
INSTALLATION: Field installable, mounts within
and powered from Keithley meter.
Adds 0.2kg (0.51 bs).
Precludes Mode I 1788 battery pack
installation.
ASSESSORIES AVAILABLE: Model 1796 - 10’ ou-t-
put mating cable, one end unter-
minated.
Model 1797 - 10’ intercon-
nect cable to 750/7502 printer.
TABLE l-2
SPECIFICATIONS, MODEL 6422 ISOLATED BCD OUTPUT
OUTPUT: 4-l/2 digit parallel BCD, polarity,
overrange bit, busy.
BUSY: Low during output update (50111s max).
OUTPUT UPDATE RATE: Same as meter conversion
rate (2.5 reading/second
typical).
CONTROL: HOLD inhibits subsequent output updates
when low.
LOGIC LEVELS: TTL/DTL and CF%X compatible.
Output High = 4.5V minimum while
sourcing lOOpA.
Low = 0.5 maxlmum while
sinking 1mA
Control High = open or 4V minimum.
Low = .5V maximum while
sinking 3.2mA
I SOLAT I ON: All outputs and controls isolated from
meter up to 30V peak, 105VoHz.
(lolon II ,4OPf tYP)
ENVIRONMENT: Operate 20°C to 30°C
Storage -25°C to +55’C.
OUTPUT CONNECTOR: 26 pin ribbon cable, unterminated.
INSTALLATION: Field installable, mounts within and
powered from Keithley meter. Adds 0.4kg (1.0 Lbs).
Precludes Model 6428 battery adapter
installation.
l-2

MODELS 1792. 6422
SECTION 2. INITIAL PREPARATION.
INITIAL PREPARATION
2-l. INTRCOUCTION.
2-2. This section provides information for r(ncomlng
inspection and preparation for use of your Model
1792/6422 BCD output option.
2-3. UNPACKING AND INSPECTION.
2-4. The Model 1792/6422 was careful ly inspected,
both mechanically and electrically before ship-
ment. Upon receiving your BCD output option, un-
pack all items from the Sh i ppingcontainer and
check for any obvious damage which may have oc-
cured during transit. Report any damages to the
shipping agent. Retain and use the original
packaging materials if reshipment is required.
The following items (Keithley Part No. in paren-
theses) are shipped with al I orders of your
option:
Model 1792
a
- PC-498 and shield Assembly
1) PC-488 Assembly (29961D)
2) Shield Assembly (30108C)
b.
- Replacement Top Cover (30136C)
c. A copy of this Instruction Manual (30155)
-
d.
- Separate Optional Cable (Model 1796 or
1797), as ordered.
Model 6422
a. Assembled PC Board (299610) with modif ied PC-
-
498 (301658).
b. Shield (301328).
-
5 Output Cable assembly with back panel and
strain rel iefs.
I) Cable assembly (302348-l)
2) Back panel (301318).
3) Two strain reliefs (27686A).
-. Mounting Hardware
d
I) Eight Standoffs (ST-94).
2) Eight 6-32 X 5/16” screws.
8.
- A copy of this Instruction Manual (30155).
2-5. PREPARATION FOR USE.
2-6. The Models 1792 and 6422 are shipped ready
for installation. Separate installation procedures
are provided. Install the Model 1792/6422 in your
instrument using the appl icable installation
procedure.
TABLE 2-l
MODEL 1792/6422 Output Connections
1792/6422 P40 1 cs-294- 1 CABLE*
FUNCTION PIN NO. PIN NO WIRE NO. b COLOR
Common 1 1 1 BRN
Common 2 2 2 RED
HOLD ( Input) 3 3 3 ORN
BUSY 4 4 4 YEL
Dl-B (2) 5 5 5 GRN
Dl-A (1) 6 6 6 BLUE
Dl-0 (8) 7 7 7 VI0
01-C (4) 8 8 8 GRAY
02-B (2) 9 9 9 WHT
02-A (1) 10 10 10 BLK
02-D (8) 11 11 11 BRN
02-C (4) 12 12 12 RED
03-B (2) 13 13 13 ORN
’
D3-A (1) 14 14 14 YEL
D3-D (8) 15 15 15 GRN
D3-C (4) 16 16 16 BLUE
04-B (2) 17 17 17 VI0
04-A (1) 18 18 18 GRAY
04-D (8) 19 19 19 WHT
D4-C (4) 20 20 20 BLK
Common 21 21 21 BRN
05 22 22 22 RED
Overrange 23 23 23 ORN
Sign 24 24 24 YEL
Common 25 25 25 GRN
Common 26 26 26 BLUE
*Part of 6422 cable assembly or optional Model 1796
cable assembly.
2-l

\NITIAL PREPARATION MODELS 1792, 6422
CARD-EDGE .
CONNECTOR
PIN 2 (TOP)
PIN 1 (UNDERNEATH)
,-Model 1792
I I - ;+ \P1?08
PL
\GROUNF CLIP : 1
ASTIC SPACER
(4 PLACES)
1792-0023-A
FIGURE 2-l. Installation of Model 1792.
2-2

MODELS 1792, 6422 INITIAL PREPARATION
2-7. MODEL 1792 INSTALLATION
2-8. The Model 1792 is installed internally in the
Model 177, 179, 179-20A, or 480 and is powered by
the instrument% line operated power supply. Instal-
lation of the Model 1792 precludes use of the Model
1788 Battery Pack. Refer to Figure 2-1 and install
the Model 1792 as fol lows:
‘t WARNI NC
Disconnect the line cord before removing the
case cover.
a. Turn off power and disconnect line cord.
-
b.
- Turn the DMM bottom side up and loosen the
four screws in the bottom cover.
c. Hold the top and bottom covers together to pre-
-
vent their separation and turn the DMM over to the
normal position.
d.
- Lift off the top cover and the calibration
shield if installed. If the Model 1788 Battery
Pack is installed, disconnect its connector from
the plug on the main printed circuit board and
remove the Model 1788. The four plastic spacers
must remain in place on the upright studs project-
ing through the main printed circuit board.
NOTE
Do not discard the calibration shield.
This shield must be installed during caii-
brat ion, as described in the Instruction Manual
for your instrument.
e.
- If the Model 1788 was removed, set the LINE/
BAT switch on the main printed circuitboard to the
LINE position.
f
-* Connect P1008 to its mating recepticle on the
printed circuit board (J1002 on the Model 480
and J1008 on the Models 177, 179 and 179-20A).
9 Install the Model 1792 in the instrument so that
it rests on the plastic spacers. The ground clip
must make contact with the upper side of the shield
on the Model 1792.
h
-0 Install the top cover that was shipped with
the Model 1792. Th is cover has a s lot to
accommodate the card edge connector of the Model
mm
i1rL.c ~
AL- Save all removed parts for reinstallation In
the event that the 1792 is to be removed at a
I ater date.
2-9. Model 1792 Output Connections.
2-10. The Model 1792 uses a 26 pin card-edge
connector (P401) to provide all input and output
connections to external equipment. This connector
mates with a Keithley CS-294-1 flat-ribbon connector
(3M 3462 or equivalent), which is not supplied.
The output connector pins are identified in Table
2-l.
Two optional cable accessories are available for in-
terfacing the Model 1792 with external equipment.
The Model 1796 is a 10 foot (3 meter) flat ribbon
cable with 26 wires and an output mating connector
(CS-294-l) on one end. The other end is left
unterminated so that a connector can be installed
that is compatible with the equipment to be
interfaced. Pin identification for the Model 1796
is the same as that given in Table 2-l for the Model
1792 output connector. The wires are color coded
with the brown wire to pin 1, the red wire to pin 2,
and so on.
The Model 1797 is a 10 foot -(3 meter) cable that
provides the connections to interface the Model 1792
with the Keithley 750/7502 Line Printer. This cable
is plug-to-plug compatible with both the Model 1792
and Hodel 750/7502 for easy installation. Table 2-2
identifies the cable connector pins and wires.
2-3

INlTlhL PREPARATION MODELS 1792, 6422
2-11. MODEL 6422 INSTALLATION
2-12. The Model 6422 is installed internally in the
Model 642 and is powered by the Model 642 line oper-
ated power supply. Installation of the Model 6422
precludes the use of the Model 6428 Battery Adapter
option. Refer to Figure 2-2 and instal I the Model
6422 as follows:
t WARNING
Disconnect the line cord before removing
the case cover.
a. Turn off power and disconnect the I ine cord.
-
b. Remove the four attaching screws and remove
-
the top cover.
c. Remove the two attaching screws from the plate
-
(or Model 6428) on the rear panel of the main-
frame. If the Model 6428 is installed, remove
it as foi lows:
I) Disconnect the connector from the plug
on the mother board.
2) Remove the attaching screw and spacer, and
remove the Model 6428 through the opening in
the rear panel.
d. Remove the front four attaching screws from
-
the mother board and replace them with the metal
spacers, as shown in Figure 2-2. These spacers
may fit snugly and require use of a wrench to in-
stall them. Take care not to cross thread or
tighten them too tight.
8. Connect P1008 to 51013 on the mother board.
-
After making the connection, place the printed
circuit board outside of the Model 642 so that
there is no strain on the cable and the board will
be out of the way during installation of the
shield and spacers in the following steps.
f. Place the shield on the spacers and attach
-
with the four screws, as shown. The printed cir-
cuit board will not fit properly unless the
shield is installed with the nut plates on the
bottom side and with the hole pattern positioned
as i I I ustrated.
I-. Install the four spacers into the shield.
h. Place the printed circuit board on the
-
spacers (component side down) and attach it with
four screws.
i
-* Connect the output cable to the card-edge con-
nectar and attach the assembly to the rear panel
of the mainframe with the two screws removed in
step c above.
L* Reinstall the case top cover.
k. Connect the Model 6422 to your equipment by
-
installing an appropriate connector on the un-
terminated end of the cable. Pin identification
for the Cable assembly connector is the same as
that given in Table 2-l for the Model 1792/6422
output connector. The wires are color coded with
the brown wire to Pin 1, the red wire to pin 2,
and so on.
L- Save all removed parts for reinstal iation in
the event that the Model 6422 is to be removed at
a later date.
2-4