INSTRUCTION MAdUAL
Models 1792,6422
Isolated BCD Outputs
Keithley instruments, Inc.
28775 Aurora Road/Cleveland, Ohio 44139/(216) 248-0400
WARRANTY
Keithley Instruments, inc. warrants this product to be free from defects
in material and workmanship for a period of 1 year from date of shipment. During the warranty period, we will, at our option, either repair
or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You will be
given prompt assistance and return instructions. Send the 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 particular use. Keithley Instruments, Inc. shall not be liable for any indirect,
special or consequential damages.
STATEMENT OF CALIBRATION
This instrument has been inspected and tested in accordance with
specifications published by Keithley Instruments, Inc.
The accuracy and calibration of this instrument are traceable to the
National Bureau of Standards through equipment which is calibrated at
planned intervals by comparison to certified standards maintained in
the Laboratories of Keithley Instruments, Inc.
KEITHLEY INSTRUMENTS, INC.
INSTRUMENT DIVISION / 28775 Aurora Road / Cleveland, Ohio 44139 / U.S.A. / (216) 248-0400 / Telex: 98-5469
WEST GERMANY: Keithley Instruments GmbH / Heiglhofstr. 5 / 8000 Munchen 70 / (089) 710020 / Telex: 52-l 2160
GREAT BRITAIN: Keithley Instruments, Ltd. I 1, Boulton Road I Reading, Berkshire RG 2 ONL / (0734) 86-12-87/88 /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
Document No. 30155, Rev. B
U.S.A.
TABLE OF CONTENTS
SECTION TITLE
1.
l-l.
l-3. COHPATIBILITY. ..................... l-l
l-5. WARRANTY INFORMATION .................. l-l
l-7. CHANGE NOTICES ..................... l-l
l-9.
l-11. SPECIFICATIONS ..................... l-l
2. INITAL PREPARATION ...................... 2-l
2-l. INTRODUCTION ...................... 2-l
2-3.
2.5.
2-7. MODEL 1792 INSTALLATION. ................ 2-3
2-9. Fidel 1792 Output Connections. ............ 2-3
2-11. IIODEL 6422 INSTALLATION. ................
3.
3-l.
3-3.
3-9. CIRCUIT DESCRIPTION. .................. 3-3
3-11.
3-14
3-16.
3-18.
3-20.
3-22. DC-to-DC Converter .................. 3-5
3-24 TEST POINT DATA. .................... 3-5
3-26.
4.
4-l. GENERAL. ........................ 4-l
4-3.
4-5.
4-7.
GENERAL INFORMATION ................... l-l
INTRODUCTION ...................... l-l
SAFETY SYMBOLS ..................... l-l
UNPACKING AND INSPECTION ................ 2-l
PREPARATION FOR USE. .................. 2-l
GPERATION ....................... .3-l
INTRODUCTION ...................... 3-l
OVERALL OPERATION. ...................
Control Circuitry. ..................
Switching Circuitry. ................. 3-4
Isolator Network ................... 3-4
Busy/Hold Circuit. .................. 3-4
Output Registers And Buffers ............. 3-5
SPECIAL HANDLING OF STATIC SENSITIVE DEVICES ......
REPLACEMENTPARTS ...................
ORDERING INFORMATION ..................
SCHEMATIC. ....................... 4-l
COM’ONENT LAYOUT ....................
PAGE
2-4
3-l
3-3
3-6
4-l
4-l
4-l
FIGURE
2-l
2-2
3-1
3-2
3-3
3-4
I LLUSTRATI GNS
TITLE PAGE
Installation of Model 1792 ............... 2-2
Installation of Model 6422 ............... 2-5
Model 1792/6422 Block Diagram. ............... 3-l
Timing Diagram ..................... 3-2
Ring Counter and Gating. ................ 3-3
Busy/Hold Circuit. ................... 3-4
UODELS 1792, 6422
GENERAL INFORMATION
SECTION 1 GENERAL lNFGRMATI(%
l-l. I NTRODUCT I ON.
l-2.
output options that convert displayed meter readings
to electrically isolated, latched, and buffered peral lel 8CD outputs.
printers or other external data hand1 ing equipment.
Logic
Output data includes sign and overrange signals. In
addition,
meter is updating data.
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,
Operating characteristics for the Models
1792 are given in their respective Specification
Tables (Table l-l and l-2).
either factory or field installed.
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.
are
I nstr unents:
The Models 1792 and 6422 are isolated BCD
These can be appl ied to I ine
levels are TTL/DTL and CMOS compatible.
a BUSY control I i ne indicates that the
The trailing edge of this
typically 2.5 readings/second.
6422 and
Both options can be
Separate
The Model s 1792 and 6422 interface options
compatible with the following Keithley
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:
same as Model 480 display.
First 3-l/2 digits at BCD auf-put
WARRANlY INFGRMATIOIJ.
l-5.
l-6.
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.
cilities in the United Kingdom and West Germany, as
well as in the
front cover of this Manual for addresses.
l-7.
l-8.
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.
fol lows:
equipment.
these precautions are ignored.
1-11. SPECIFICATIONS.
l-12.
and 6422 are given
respectively.
The Warranty is given on the inside front
Keithley maintains service fa-
United States. Check the inside
CHANGE NOTICES.
Improvements or changes to the equipment which
Safety symobls used in thls manual are as
IM3oRTANT
The ! n symbol can be found in various places in
this manual. Careful ly read the associated CAUTION statements with regard to proper use and
handling of the equipment. Damage to the equip-
ment may occur if these precautions are ignored.
This
t
this manual.
the equipment which are potential shock hazards.
Careful ly read the associated WARNING statements
with regard to proper use and hand1 Ing of the
symbol can be found In various places in
This symbol indicates those areas on
Serious personal injury may result if
Detailed specifications for the Model 1792
In Tables l-l and 1-2,
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:
OUTPUT UPDATE RATE:
CONTROL : E inhibits subsequent output updates
LOGIC LEVELS: TTL/DTL and CMOS compatible.
ISOLATION:
ENVIRONMENT: Operate 0 to 55”C, 0 to 805 RH.
OUTPUT CONNECTOR:
INSTALLATION: Field installable, mounts within
Low during output update (5Oms max).
Same as meter conversion rate
(2.5 reading/second typical).
when low.
Output High = 4.5V minimum while
sourcing lOOkA.
Low =
0.5V maximum while
sinking 3.2mA.
Control High = open or 4V minimum.
Low =
All outputs and controls isolated from
meter up to 1400V peak, 105V*Hz.
(lOlO, ,ll40pf typ1
Storage’ -25 to 7O’C.
26 pin card edge, mates with
CS294-1 (3M 3462 or equivalent)
and powered from Keithley meter.
Adds 0.2kg (0.51 bs).
Precludes Mode I 1788 battery pack
installation.
.5V maximum while
sinking 1mA.
TABLE l-2
SPECIFICATIONS, MODEL 6422 ISOLATED BCD OUTPUT
OUTPUT:
BUSY: Low during output update (50111s max).
OUTPUT UPDATE RATE:
CONTROL : HOLD inhibits subsequent output updates
LOGIC LEVELS:
I SOLAT I ON :
ENVIRONMENT:
OUTPUT CONNECTOR: 26 pin ribbon cable, unterminated.
INSTALLATION:
powered from Keithley meter. Adds 0.4kg (1.0 Lbs).
Precludes Model 6428 battery adapter
installation.
4-l/2 digit parallel BCD, polarity,
overrange bit, busy.
Same as meter conversion
rate (2.5 reading/second
typical).
when low.
TTL/DTL and CF%X compatible.
Output High = 4.5V minimum while
sourcing lOOpA.
Low = 0.5 maxlmum while
sinking 1 mA
Control High = open or 4V minimum.
Low = .5V maximum while
sinking 3.2mA
All outputs and controls isolated from
meter up to 30V peak, 105VoHz.
(lolon II ,4OPf tYP)
Operate 20°C to 30°C
Storage -25°C to +55’C.
Field installable, mounts within and
ASSESSORIES AVAILABLE: Model 1796 - 10’ ou-t-
put mating cable, one end unter-
minated.
Model 1797 - 10’ intercon-
nect cable to 750/7502 printer.
l-2
MODELS 1792. 6422
INITIAL PREPARATION
SECTION 2. INITIAL PREPARATION.
2-l. INTRCOUCTION.
This section provides information for r(ncomlng
2-2.
inspection and preparation for use of your Model
1792/6422 BCD output option.
UNPACKING AND INSPECTION.
2-3.
2-4. The Model 1792/6422 was careful ly inspected,
both mechanically and electrically before shipment.
pack all items from the Sh i ppingcontainer and
check for any obvious damage which may have occured during transit.
shipping agent. Retain and use the original
packaging materials if reshipment is required.
The following items (Keithley Part No. in parentheses) are shipped with al I orders of your
option:
Model 1792
Model 6422
Upon receiving your BCD output option, un-
Report any damages to the
a - PC-498 and shield Assembly
1) PC-488 Assembly (29961D)
2) Shield Assembly (30108C)
Replacement Top Cover (30136C)
b.
c. A copy of this Instruction Manual (30155)
d. - Separate Optional Cable (Model 1796 or
1797), as ordered.
a. Assembled PC Board (299610) with modif ied PC-
498 (301658).
Shield (301328).
b.
-
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).
d
-. Mounting Hardware
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
for installation.
are provided.
instrument using
procedure.
1792/6422
FUNCTION
Common
Common
HOLD ( Input)
BUSY
Dl-B (2)
Dl-A (1)
Dl-0 (8)
01-C (4)
02-B (2)
02-A (1)
02-D (8)
02-C (4)
03-B (2)
D3-A (1)
D3-D (8)
D3-C (4)
04-B (2)
04-A (1)
04-D (8)
D4-C (4)
Common
05
Overrange
Sign
Common
Common
*Part of 6422 cable assembly or optional Model 1796
cable assembly.
Models 1792 and 6422
Separate installation procedures
Install the Model 1792/6422 in your
the
appl icable
TABLE 2-l
MODEL 1792/6422 Output Connections
P40 1 cs-294- 1 CABLE*
PIN NO.
1 1 1 BRN
2 2 2 RED
3 3 3 ORN
4 4 4 YEL
5 5 5 GRN
6 6 6 BLUE
7 7 7 VI0
8 8 8 GRAY
9 9 9 WHT
10 10 10 BLK
11 11 11 BRN
12 12 12 RED
13 13 13 ORN
’
14 14 14 YEL
15 15 15 GRN
16 16 16 BLUE
17 17 17 VI0
18 18 18 GRAY
19 19 19 WHT
20 20 20 BLK
21 21 21 BRN
22 22 22 RED
23 23 23 ORN
24 24 24 YEL
25 25 25 GRN
26 26 26 BLUE
PIN NO
are
WI RE NO. b COLOR
shipped ready
installation
2-l
\NITIAL PREPARATION
MODELS 1792, 6422
CARD-EDGE .
CONNECTOR
I I
PIN 2 (TOP)
PIN 1 (UNDERNEATH)
-
,-Model 1792
;+ \P1?08
\GROUNF CLIP :
1
2-2
PL
ASTIC SPACER
(4 PLACES)
FIGURE 2-l.
1792-0023-A
Installation of Model 1792.
MODELS 1792, 6422
INITIAL PREPARATION
2-7. MODEL 1792 INSTALLATION
The Model 1792 is installed internally in the
2-8.
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.
the Model 1792 as fol lows:
‘t
Disconnect the line cord before removing the
case cover.
a. Turn off power and disconnect line cord.
Turn the DMM bottom side up and loosen the
b.
-
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.
Lift off the top cover and the calibration
d.
-
shield if installed.
Pack is installed,
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.
Do not
This shield must be installed during caii-
brat ion,
for your instrument.
as described in the Instruction Manual
Refer to Figure 2-1 and install
WARN I NC
If the Model 1788 Battery
disconnect its connector from
NOTE
discard the calibration
shield.
Install the Model 1792 in the instrument so that
9
it rests on the plastic spacers.
must make contact with the upper side of the shield
on the Model 1792.
h
Install the top cover that was shipped with
-0
the Model 1792. Th is cover has a s lot to
accommodate the card edge
mm
i1rL.c ~
Save all removed parts for reinstallation In
AL-
the event that the 1792 is to be removed at a
I ater date.
Model 1792 Output Connections.
2-9.
2-10.
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 interfacing 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.
unterminated so that a connector can be installed
that is compatible with the equipment to be
interfaced.
is the same as that given in Table 2-l for the Model
1792 output connector.
with the brown wire to pin 1, the red wire to pin 2,
and so on.
The Model 1792 uses a 26 pin card-edge
Pin identification for the Model 1796
connector of the Model
The other end is left
The wires are color coded
The ground clip
e. - If the Model 1788 was removed, set the LINE/
BAT switch on the main printed circuitboard to the
LINE position.
Connect P1008 to its mating recepticle on the
f
-*
printed circuit board (J1002 on the Model 480
and J1008 on the Models 177, 179 and 179-20A).
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.
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.
This cable
2-3
INlTlhL PREPARATION MODELS 1792, 6422
Connect P1008 to 51013 on the mother board.
2-11. MODEL 6422 INSTALLATION
2-12.
Model 642 and is powered by the Model 642 line operated 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:
The Model 6422 is installed internally in the
WARNING
t
Disconnect the line cord before removing
the case cover.
8.
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.
Place the shield on the spacers and attach
f.
with the four screws, as shown.
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.
The printed cir-
a. Turn off power and disconnect the I ine cord.
Remove the four attaching screws and remove
b.
-
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
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.
Remove the front four attaching screws from
d.
the mother board and replace them with the metal
spacers, as shown in Figure 2-2.
may fit snugly and require use of a wrench to install them.
tighten them too tight.
Model 6428 is installed, remove
These spacers
Take care not to cross thread or
Install the four spacers into the shield.
I-.
Place the printed
h.
spacers (component side down) and attach it with
four screws.
Connect the output cable to the card-edge con-
i
-*
nectar and attach the assembly to the rear panel
of the mainframe with the two screws removed in
step c above.
Reinstall the case top cover.
L*
Connect the Model 6422 to your equipment by
k.
installing an appropriate connector on the un-
terminated end of the cable.
for the Cable assembly connector is the same as
that given in Table 2-l for the Model 1792/6422
output connector.
the brown wire to Pin 1, the red wire to pin 2,
and so on.
Save all removed parts for reinstal iation in
L-
the event that the Model 6422 is to be removed at
a later date.
The wires are color coded with
circuit board on the
Pin identification
2-4
MODELS 1792, 6422
INITIAL PREPARATION
MOD I F I ED PC-498
(30165B)
STANDOFF (8)
FIGURE 2-2.
MAINFRAME
6422-0032-B
ASSEMBLY
Installation of Model 6422
2-5
INITIAL PREPARATION
MODELS 1792. 6422
TABLE 2-2
Model 1797 Cable Connections
1792
FUNCTION
Common
Common
HOLD (Input)
BUSY 4
Dl-B (2)
Dl-A (1) 6
Dl-D (8) 7
Dl-C (4) 8
D2-B (2) 9
D2-A (1) 10
02-D (8)
D2-C (4) 12
D3-B (2) 13
03-A (1) 14
D3-D (8)
D3-C (4) 16
D4-B (2) 17
D4-A (1)
D4-D (8)
04-C (4)
Common 21
05 22
OVERRANGE
SIGN 24
Common
Common 26
cs-294- 1
PIN NO.
11
15
18
19
20
23
25
CABLE
WIRE NO.
AND COLOR
1
2
3
5
1 BRN
2 RED
3 ORN
4 YEL
5 GRN 2
6 BLUE
7 VI0
8 GRAY
9 WHT
10 BLK
11 BRN
12 RED
13 ORN
14 YEL
15 GRN 41
16 BLUE
17 VI0
18 GRAY
19 WHT
20 BLK 8
21 BRN 43,44,45
22 RED
23 ORN
24 YEL
25 GRN 12
26 BLUE
CS-27 1
PIN NO.
9
14
15
13
18
37
19
22
5
23
6
39
38
40
24
7
25
42
11
10
28,29
750/75op
FUNCTION
8-l gnd.
Common
HOLD (Output)
EXTERNAL PRiNT
3-2
3-l
3-8
3-4
4-2
4-l
4-8
4-4
5-2
5-l
5-8
5-4
6-2
6-l
6-8
6-4
7-2,7-4,7-8 gnd.
7-l
10-l
8-4
10-4 gnd.
10-8, I O-2 gnd.
2-6
O=On Scale
l=Overrai+
*Pr i nter Format
10 9 8 7 6 5 4 3 2 1 Column
L
SIGN
(+implied)
MODELS 1792, 6422
OPERATION
SECTION 3. OPERATION.
3-1. INTRODUCTION.
3-2.
to provide overall operation, circuit descriptions,
This section describes operation of the Model
1792/6422.
apply to both models.
test point data and special handling requirements
for static sensitive devices.
OVERALL OPERATION.
3-3.
3-4. Figure 3-l shows the Model 1792/6422 in block
diagram form.
verting multiplexed BCO input data into synchronous
serial data.
an opto-electric coupler network and loaded into a
twenty bit shift register.
and appears at the output in parallel BCD format.
The STROBE and CLOCK lines come from the meter
3-5.
motherboard and provide timing for the 1792/6422.
The control
counter. The divider is phase-locked to the STROBE
Except where noted, the descr lptions
The information is arranged
The 1792/6422 operates by first con-
Serial data is then transmitted across
Data is then buffered
consists of a divider and a ring
pulse and divides the lOOkliz CLOCK by ten to produce the 1OkHz SYNC train. The ring counter output
drives the switching to convert the multiplexed BCD
digit data into a serial one bit format. The digit
five (D5) line is decoded to serialize the SIGN and
OVERRANGE I ines.
3-6.
couplers and buffers. The SYNC and DATA pul ses
are transmitted with the opto-couplers normally off
to conserve power.
3-7.
BUSY/HOLD network which controls the output shift
reg i ster. This network consists of a flip-flop, one
shot, and gating.
data update. However,
data wiil be ioaded, and the output wiii not change.
With the HOLD line high, data is updated at the
meter
second.
The isolating network consists of two opto-
The SYNC train after transmission goes into a
The BUSY output goes low during
if the HOLD I ine is low, no
conversion rate,
typically 2.5 readings/
Figure 3-l.
OUTPUT COMMON
Model 1792/6422 Block Diagram
3-l
OPERAT I ON
STROBE
SYNC
GNO +-
I
I
I
I
t5v
2mSEC
MODELS 1792, 6422
I
I
I
I
4
39DmSEC
L
mu uuuu uuuu luuu
50
USE&+-
BUSY -
HOLD
sl-
-4
FLAG
SYNC
SHIFT
CLOCK
I”
II
I
I
II DATA I
I
L
I
I
7
I
’
d +t--20DnSEC iii hi. ~ ~
4
11 1 I I ’ 1 I I I 1
II I I I 1 I I I I I
1
I-*-- *--- .--- *--- au--
I
II
I
I
I
I’
//
7 y uSEC
+--2p SEC MIN.
-
1 1 1 I I I
’ I I
100
II
I 1 I I I I
I
I I
I I
r ZC
4
I
c- +5v
l
~380 mSEC
DON’T CARE
-!
= 20 mSEC COMMON
uuuu urn
I
I
I
I
I
I
3
I
I
I
I ~
I
I
I
I
I
I
f
I
I
I
I
3-2
FIGURE 3-2.
1792-0033-A
Timing Diagram.
MODELS 1792, 6422
OPERATION
3-a.
(+5V for the Model 1792 and t6V for the Model
6422).
provided by a DC-to-DC converter running at lOOkliz.
3-9.
3-10.
of the major circuit blocks described in Overall
Operation of the Model 1792/6422. The descriptions
are referenced to the Model 1792/6422 (schematic
299650,
schematics are also provided.
the Model 1792/6422 Waveform Diagram (Figure 3-2).
3-11.
3-12.
counter (U414) and a ring
gating.
produce 1OkHz optional transmission of the DATA and
SYNC tral ns across the opto-electric couplers.
STROBE pulses phase-lock the counter by presetting
Input power is furnished by the host meter
The power for the isolated (output) side is
CIRCUIT DESCRIPTIONS.
This section provides detailed descriptions
Page 4-4).
Control Circuitry.
The control
U414 divides the 1OOkHz CLOCK by ten to
Where necessary, simi pl if led
Timing is shown in
consists of a divide-by-ten
counter (U41lA) with
The
it to 2 on each pulse.
long term operation.
3-13.
and gating Is given in Figure 3-3.
pulse enables the transfer of one digit (four bits)
one bit at a time. There are five STROBE pul ses in
each complete data transfer.
STROBE pulse sets the latch comprised of U415A and
U415B, enabl ing U415D to gate the 1OkHz SYNC pulses
to the opto-electric coupler and to the CLOCK input
of U411A.
4
output lines Ql through Q4 to drive the quad switch
and serialize the digit data.
latch when the Ql through Q4 I ines are clocked to
al I zeros,
STROBE pulse. Since the latch is not reset until
U411A is clocked to al I zeros, a pulse of c- 500
nanoseconds is produced on the SYNC I ine after each
4 SYNC pul ses, but this is too fast to be acknow-
ledged by the opto electric couplers.
A simpl i fled schematic of the ring counter
U41lA gates a elll in sequence on its
and it remains in reset unti I the next
Th 1 s ensures synchronous
Each STROBE
In operation, the
U415C resets the
STROBE
HIGH l/2 CLOCK PULSE
AFTER 94 GOES HIGH.
FIGURE 3-3.
Ring Counter and Gating.
To U41lB
TO QUAD SWITCH
(U4 13)
1792-0036-A
3-3
OPERAT \ ON MODELS 1792, 6422
3-14.
3-15.
provided by U413 and U416A.
4: 1 multi plexer.
nected through to the DATA opt-o-electric coupler
when its respective control I ine is driven high by
the ring counter (U4llAI.
dual 2:’ multiplexer, switching is controlled by the
digit 5 (D5) line.
significant digit and is transmitted first.
it is always a nOw or a lllw, bits 2, 3 and 4 are not
needed and can be used to transfer other information.
When the D5 line is high, the overrange and sign
status is sent on bits 4 and 3, respectively.
Conversely,
digits 4 through 1 are sent.
3-16.
3-17.
optically coupled isolators, two transistors and
their associated biasing resistors.
Switching Circuitry.
Switching to serialize the input BCD data is
U413 is connected as a
One of its input lines is con-
U4 16A is connected as a
The fifth digit is the most
Since
when the 05 line is low, 88 and 84 for
Isolator Network.
The isolator network is comprised of two
The isolators
provide 101oD isolation and are normally off to
conserve power. The transistors invert the pulses
and serve both as wave shapers and low impedance
buffers into the high impedance CMOS circuits.
3-18. Busy/Hold Circuit.
3-19.
cuit is given in Figure 3-4. The BUSY I ine always
goes low during a potential data transfer.
BUSY goes low, the f I ip-flop Is clocked and the HOLD
I ine checked to see
desired. If the HOLD line is high, the FLAG is set,
enabl ing U409D to gate the SYNC pul se train.
BUSY line
mi I I iseconds.
resets the fl ip-f lop and no data transfer can occur
until it goes low again. This will occur when the
one-shotmultivibrator
pulse of the next SYNC train.
A simpl ifled schematic of the BUSY/HOLD cir-
if a new data transfer is
remains
When the BUSY I ine returns high, it
for
low
is triggered by the first-
approximately 20
When
The
HOLD
BUSY
*U404 and U408 PROVIDE -400 NANOSECOND
DELAY TO ENSURE THAT FF RESET LINE IS LOW
BEFORE CLOCKING.
FIGIURE 3-4.
Busy/Hold Circuit.
SYNC CLOCK I NG TO
OUTPUT SHIFT REGISTERS.
1792-0035-A
3-4
MODELS 1792, 6422
OPERATION
3-20. Output Registers And Buffers.
3-21. Five 4-stage serial-input/paral lel-ouiput
registers are connected together to form the twenty
bit output shift register. Serial input data is ap-
plied to the lrD1t input of U407A. Data is set up on
the fal I ing edges of the SYNC pulses and latched on
the rising edges. Data is shifted into the outpuf
register in a seq uBnce that can be determined by
reading the output line identification from top to
bottom on Schematic 29965D, page 4-4.
transfer is complete, the display information is
available at the oufput card-edge connector in a
buffered parallel BCD format.
3-22. DC-to-DC Converter.
3-23.
applied to switching transistor 0403. 0 i ode CR402
The 1OOkHz clock is buffered by U410 and
After data
TABLE 3-l.
Test Point Data
shunts one half cycle of buffer drive and provides
optimal switching of 0403 to prodllce maximum voltage
in the secondary of the transformer.
I imits the base current to 0403.
across transformer T401 and half- wave rectified by
CR401. Capacitor C401 and voltage regulator VR401
provide a stable positive five volt supply to the
isolated circuits.
3-24. TEST POI NT DATA.
3-25. The Model 1792/6422 has ten test points that
can be used for trocbl eshoot I ng or confidence test-
ing. Test point signals are described in Table 3-l.
The test points are accessible by removing the
instrument top cover as described in the applicable
instal lation procedure (i.e, Para. 2-l for Model
1792 or Para. 2-11 for Model 6422).
R411 I imits
Power is pul sed
Test
Point
TP’
TP2
TP3
TP4
TP5
TP6
TP7
TP8
TP9
Signal
1OkHz. Clock, SVpp, 50% duty cycle
SYNC (See Timing Diagram Figure 3-l).
Digital non-isolated common, OV reference
for TPl and TP5.
Non-isolated positive supply from meter
(6V f 5% Model 6422 and 5V f 5% for Model
1792).
DATA (See Timing Diagram Figure 3-l).
Complement of TP2.
Isolated DATA, same as TP5.
Isolated t5V f 0.25V.
SYNC SHIFT CLOCK-If HOLD is high,
same as TP2.
See Timing Diagram Figure 3-l.
If HOLD is low, +5V (high).
Reference
TP3
TP3
TP3
TP3
TPlO
TP’O
TP’O
TP’O
Isolated common, OV reference for TP6 thru
TP9.
3-5
OPERAT I ON
MODELS 1792, 6422
3-26.
SENSITIVE DEVICES.
3-27. CMCS devices are designed to function at
very high impedance levels for low power consump-
t ion. For this reason, a normal static charge build
up on your person or clothing can be sufficient to
destroy these devices.
static sensitive devices In your Model
and provide instructions on how to avoid damaging
them when they must be removed/replaced.
SPECIAL HANDLING OF STATIC
The fol lowing steps I is-t the
1792/6422,
a. Static sensitive devices:
Keithley
Part Number
IC-107
IC-136
IC-102
IC-106
IC-105
IC-221
IC-145
I c-222
The above integrated circuits should be
b.
handled and transported only In protective con-
ta i ners. Typically they wil I be received in metal
tubes or static protective foam. Keep the devices
Reference
Designation
U401-U404 ,U408
u405-u407 ,u411
u409, u415
u410
U412
u413
u414
U416
in their original containers until ready for use.
Remove the devices from their protective con-
C.
talners only at a properly grounded work bench or
table, and only after grounding yourself by using
a wrist strap.
Handle the devices only by the body.
d.
touch the pins.
NOTE
P1008 is shipped with a piece of conductive
foam covering the pins to prevent static
damage.
placed If you disconnect P1008 to remove
your BCD option from its host instrunent.
e. Any printed circuit board into which a device
-
I s to be inserted must al so be grounded to the
bench or table.
f. - Use only anti-static type solder suckers.
Use only grounded tip soldering irons.
3-0
After soldering the device into the board,
h.
-
or properly Inserting it into the mating recep-
tacle, the device is adequately protected and
normal hand1 ing can be resuned.
This conductive foam should be re
Do not
3-6
MODELS 1792, 6422
SECTION 4 REPLACEMENT PARTS
4-l. GENERAL.
This section contains information for order-
4-2.
ing replacement parts.
(Table 4-2, Page4-2) is arranged in alphabetical
order of the Circuit Designations of the components.
A Cross-Reference List of Manufacturers, containing
their addresses,
DRDERING INFORMATION.
4-3.
4-4.
concerning replacement parts, contact your Keithley
representative or the Factory. See the inside front
cover for addresses.
following information.
To place an order,
is given in Table 4-l.
The Replaceable Parts List
or to obtain information
When ordering, include the
REPLACEMENT PARTS
TABLE 4-l.
Cross-Reference of Manufacturers~
MFG.
CODE NAME AND ADDRESS
CLB
F-l
ITT
K-l Keithley Instruments, Inc.
Centralab Division
Milwaukee, WI 53201
FaIrchild Inst. Corp.
Mountain View, CA 94043 07263
Components
Lawrence, MA 15238
Cleveland, Ohio 44139
FED.
SUPPLY
CCQE
71590
88164
a. Equipment Model Number.
Part Description.
b.
-
c. Circuit Designation (if applicable).
Keithley Part Number.
d.
-
SCHEMATIC
4-5.
Model 1792/6422 BCD Option:
4-6.
Schematic No. 29965D page 4 - 4.
COFPDNENT LAYOUT.
4-7.
Physical location of the components is shown
4-8.
in Component Layout No. 29961D, Pageq-5.
MEP Mepco, Inc.
Morrlstcwn, NJ 07960
NAT
NCI
RCA RCA Corporation
T-l Texas I nstruments, Inc.
Nationa! Semi Corp.
Santa Clara, CA 95051
Nationa I Components, Inc.
West Pal m Beach, FL
Morrestown, NJ 08050
Dallas, TX 75231
8003 1
27014
02734
01295
4-l
REPLACEMENT PARTS
MODELS 1792, 6422
TABLE 4-2
REPLACEABLE PARTS LIST
Circuit
3es ig.
/
4T40 I
/
4T402
I
2401
I
c402
I
C403
I
D404
I
CR401
I
CR402
I
P1008
I
PI008
I
Q401
I
Q402
I
Q403
I
R40l
I
R402
I
R403
I
R404
I
R405
I
R406
I
R407
I
R408
I
R409
I
R410
I
R4 11
I
R412
I
R413
Location Mfr. Mfr. Keithley
Description
IC, Optical Iy-Coupled Isolator D-4 F-4 F-l
IC, Optically-Coupled Isolator D-2 F-4 F-l FCD 820
Cap, 4.7uF, 2OV, ETT
Cap, 0.3311F, 2OV, ETT E-5
Cap, O.luF, 16V, CerD
Cap, 0.3311F, 2OV, ETT
Diode, Si I icon, 75mA, 75V
Diode, Si I icon, 75mA, 75V B-2 D-5 T-l lN914 RF-28
Cable Assembly (1792)
Cable Assembly (6422)
Transistor NPN Silicon D-4 E-4 T-l 2N3904 TG47
Transistor, NPN, Silicon
Transistor, NPN, Silicon C-l D-5 T-l 2N3904 TG-47
lOKD,t5%, 1/4W, CarbF E-6 D-3
lOOKR,*5%, 1/4W, CarbF E-5
lOKD,i5%, 1/4W, CarbF
lOKD,k5%, l/4W, CarbF
lOOKl2,*5%, 1/4W, CarbF
lOOKG,k5%, 1/4W, CarbF
39OO,i5%, 1/4W, CarbF
3908,*5%, 1/4W, CarbF
lOOKJ2,*5%, 1/4W, CarbF
lOKn,f5%, 1/4W, CarbF
lKn,tS%, 1/4W, CarbF
lOOKD,k5%, 1/4W, CarbF
lOOKn,k5%, 1/4W, CarbF
Sch. Pcb.
E-l D-4
F-4 ITT
B-l
A-4
E-l D-4 T-l lN914
A-2 H-5 K-l --- 27961A-l
A-2 H-5 K-l --- 2796 l A-2
D-2
E-3 E-4
E-2
D-4
D-2
D-4 F-4 MEP CR25* R-76-390
D-3
D-5
C-l D-5
B-l
D-4
D-3
D-5
F-5
F-4 T-l
F-4
F-4 MEP CR25”
E-4 MEP
F-4 MEP CR25”
F-4 MEP CR25” R-76-390
F-4 MEP CR25” R-76- 1OOK
D-5
E-4 MEP CR25” R-76-100K
F-4 MEP CR25* R-76- 1OOK
Code Des lg. Part No.
FCD 820 I C-82
I C-82
NCI KNS475A020K c-179-4.7
TAPA.33KZO
CLB UK16-104 C-238-. I
ITT
MEP CR25” R-76- 10K
MEP
MEP
MEP CR25” R-76- IOK
MEP CR25” R-76- 1K
TAPA .33K20 C-204-.33
2N3904 TG47
CR2 5”
CR25” R-76- 1OK
CR25”
C-204- .33
RF-28
R-76- 1 OOK
R-76-10K
R-76- 1OOK
R-76- IOOK
4-2
T401
u401
U402
u403
u404
u405
*Manufacturers Des ignat ion includes Part Descr Ipt ion; e.g., CR25,
Transformer, Power
IC, CMOS, Hex Buffer
IC, CMOS, Hex Buffer F-2,3 E-3
IC, CMOS, Hex Buffer
IC, CMOS, Hex Buffer F-5,D-5
IC, CMOS, Duel 4-Stage Static Shift
Reg i ster.
D-l
F-l ,E6
F-4
F-1,2
D-4 K-l --- TR- 170
D-3
E-3
F-3
D-4 RCA CD4015AE IC-136
RCA CD4050AE 10107
RCA CD4050AE IC-107
RCA CD4050AE
RCA CD4050AE IC-107
lOKP,*5%, 1/4W, CarbF for R40l.
IC-107
MODELS 1792, 6422
REPLACEMENT PARTS
TABLE 4-2 (CONT.1
REPLACEAEILE PARTS t fSf
Circuit
Desig.
U406
u407
U408
u409
u410
u411
U412
u413
u414
u415
U416
VR401
DescrIptiOn
IC, CMDS, Dual 4-Stage Static Shift
Reg i ster. F-3,4
IC, CMOS, Dual 4-Stage Static Shift
Register.
IC, CMOS, Hex Buffer
IC, CMOS, Quad 2-Input NAND Gate
IC, CMOS, Hex lnverter
IC, CMOS, Dual 4-Stage Static Shift
Reg i ster.
IC, CMOS, Dual 4-Input NOR Gate
IC, CMOS, Quad Analog/Digital Switch
IC, CMOS, Presettable Divide-by-N
Counter.
IC, CMOS, Quad 2-Input NAND Gate
IC, CMOS, Quad 2 Channel Data Selector B-5
IC, 3-Terminal,
t5V Regu I ator f 5% E-l
scfa.
D-5,F-4
E-2,4,5,
DE-4,5
ABCD-1,2,3,5 D-5
CD-3
B-4,A-5 E-5 RCA
C-5
B-2 D-5
BC-3,4 E-5
LocatIon
Mfr.
Pcb. Coda
E-4 RCA
E-4 RCA
F-4 RCA
F-4 RCA
RCA
E-5 RCA
F-5 NAT
RCA
RCA
E-5 NAT
D-4 NAT
Mfr.
Desig.
CD4015AE
CD4015AE
CD4050AE
CD401 1AE
CD4049AE
CD40 15AE
CD4002AE
CD40 16CN
CD4018AE
CD401 IAE
CD45 19BCN
LM78L05ACZ
Keith1.y
Part No.
IC-136
10136
IC-107
10102
IC-106
10136
10105
10221
10145
10102
I c-222
I C-223
4-3
Sxa (u -
-- ----.
il.l.m’
.
8
Z’
1 I
-
4-4
P
VI
SERVICE FORM
Model No.
Name
Company
Address
City
Serial No. P.O. No.
State
Date
Phone
Zip
List all control settings and describe problem.
(Attach additional sheets as necessary. 1
Show a block diagram of your measurement system including all instruments connected (whether power
is turned on or not). Also describe signal source.
Where is the measurement being performed? (factory, controlled laboratory, out-of-doors, etc.)
What power line voltage is used? Variation?
Frequency? Ambient Temperature?
Variation?
OF. Rel. Humidity? Other?
OF.
Any additional information. (If special modifications have been made by the user, please describe below.)
*Be sure to include your name and phone number on this service form.
KEITHLEY INSTRUMENTS, INC.
INSTRUMENT DIVISION I 28775 Aurora Road / Cleveland, Ohio 44139 / U.S.A. / (216) 248-0400 / Telex: 98-5469
WEST GERMANY: Keithley Instruments GmbH / Heiglhofstr. 5 / 8000 Munchen 70 / (089) 710020 / Telex: 52-12160
GREAT BRITAIN: Keithley instruments, Ltd. / 1, Boulton Road / Reading, Berkshire RG 2 ONL / (0734) 86-l 2-87/88 /Telex: 84-7047
FRANCE: Keithley Instruments SARL / 2, Bis Rue Leon Blum / B.P. 60 / 91 121 Palaiseau Cedex / (6) 01 1-51-55 I Telex: 600-933
NETHERLANDS: Keithley Instruments BV I Arkelsedijk 4 I Postbus 559 / 4200 AN Gorinchem I (0) 1830-25577 I Telex: 24-684
SWITZERLAND: Keithley instruments SA / Kriesbachstr. 4 / 8600 Dubendorf / 01/821-94-44 / Telex: 57-536
AUSTRIA: Keithley Instruments Ges.m.b.H. / Db’blinger Haupstr. 32 I 1190 Wien / 314 289 / Telex: 13-4500
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