Keithley 7077, Инструкция по эксплуатации

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Service Information
4-8
4.4.5 Path isolation tests
Path isolation tests check the leakage resistance (isolation)
between adjacent paths. A path is defined as the HIGH (H)
and LO (L) circuit from a row to a column that results from
closing a particular crosspoint. The test is performed by ap-
plying a voltage (+42V) across two adjacent paths and then
measuring the leakage current across the paths. The isolation
resistance is then calculated as R = V/I. In the following pro-
cedure, the Model 6517 functions as both a voltage source
and an ammeter. In the V/I function, the Model 6517 inter-
nally calculates the resistance from the known voltage and
current levels and displays the resistance value.
1. Remove all power from the switching matrix and
switching matrix cards.
2. Install the Model 7077 in the Model 708 or in slot 1 of
the Model 707.
3. Connect the Model 6517 to ROWS A and B as shown in
Figure 4-5. Make sure the voltage source is in standby
and there are no other connections to the card.
4. On the Model 6517, select the 20pA range, and enable
zero check and then zero correct. Leave zero correct en-
abled for the entire procedure.
5. On the Model 6517, select the 200pA range, and release
zero check.
6. On the Model 6517, press suppress to cancel offset cur-
rent, and then enable zero check.
7. On the Model 6517, set the voltage source for +42V, and
select the 20nA current range. Make sure the voltage
source is in standby.
8. Place the Model 6517 in the V/I measurement function.
9. Turn on the Model 707/708, and program it to close
crosspoints A1 and B2.
10. On the Model 6517, disable zero check, and press OP-
ERATE to 42V.
11. After allowing the reading on the Model 6517 to settle,
verify that it is >10G
Ω
. This measurement is the leakage
resistance (isolation) between ROW A, COLUMN 1 and
ROW B, COLUMN 2.
12. Enable zero check, and then place the Model 6517 in
standby.
13. Turn off the Model 707/708, and make sure all power is
removed from the circuit.
14. Disconnect the Model 6517 from ROWS A and B. In a
similar manner, reconnect it to ROWS B and C (picoam-
meter high and voltage source low to ROW B and volt-
age source high and low to ROW C).
15. Turn on the Model 707/708, and program it to close
crosspoints B2 and C3.
16. On the Model 6517, disable zero check, and press
OPERATE to 42V.
17. After allowing the reading on the Model 6517 to settle,
verify that it is >10G
Ω
.
18. Using Table 4-2, repeat steps 13 through 18 for the rest
of the path pairs starting with test number 3.