Service Information
5-5
Contact potential tests
These tests check the EMF generated by each relay contact
for each channel. The tests simply consist of using a sensitive
DVM (Model 182) to measure the contact potential.
Perform the following procedure to check contact potential
of each path:
1. Turn off the Model 7001/7002 if it is on.
2. Set the Model 182 to the 3mV range, short the input
leads, and press REL READING to null out internal off-
set. Leave REL enabled for the entire procedure.
3. Connect the Model 182 to channel 1 as shown in Figure
5-3.
4. Install the switch card in slot 1 (CARD 1) of the
Model 7001/7002 if it is not already installed.
5. Turn on the Model 7001/7002.
6. Program the Model 7001/7002 to close channel 1!1.
7. Verify that the reading on the Model 182 is <4
µ
V. This
measurement is the contact potential of the channel.
8. Repeat the basic procedure in steps 1 through 7 to test
the rest of the channels of the Model 7036.
Channel to channel isolation tests
These tests check the leakage resistance (isolation) between
adjacent channels. A channel is simply the circuit from the
input (IN) to the output (OUT) that results by closing the
channel relay.
In general, the test is performed by applying a voltage
(+42V) across two adjacent channels and then measuring the
leakage current across the channels. The isolation resistance
is then calculated as R = V/I. In the following procedure, the
Model 6517A functions as both a voltage source and an
ammeter. In the R function, the Model 6517A internally cal-
culates the resistance from the known voltage and current
levels and displays the resistance value.
Figure 5-3
Contact potential testing
Each channel:
7036
IN
OUT
HI
LO
KEITHLEY 182 SENSITIVE DIGITAL VOLTMETER
TRG
SRQ
REM
TALK
LSTN
Model 182
Model 1484
Low Thermal Cable
(Unterminated)
