Keithley 7012-S, Instruction Manual, Page: 69 / 93

Service Information
5-7
5.3.7 Path isolation tests
These tests check the leakage resistance (isolation) be-
tween adjacent paths. A path is de
Þ ned as the high (H)
and low (L) circuit from a row to a column that results
by closing a particular crosspoint. In general, the test is
performed by applying a voltage (+100V) across two
adjacent paths and then measuring the leakage current
across the paths. The isolation resistance is then calcu-
lated as R = V/I. In the following procedure, the Model
617 functions as both a voltage source and an ammeter.
In the V/I function, the Model 617 internally calculates
the resistance from the known voltage and current lev-
els, and displays the resistance value.
1. Turn the Model 7001 off if it is on.
2. Jumper the high (H) terminal to the low (L) termi-
nal for each row (see Figure 5-5).
3. Connect the Model 617 to Rows 1 and 2 as shown
in Figure 5-5. Make sure the voltage source is in
standby. Also, make sure there are no other con-
nections to the card.
4. Install the Model 7012 in slot 1 of the Model 7001.
WARNING
The following steps use high voltage
(100V). Be sure to remove power
from the circuit before making con-
nection changes.
5. On the Model 617, select the 2pA range, and enable
zero check and zero correct in that order. Leave
zero correct enabled for the entire procedure.
6. On the Model 617, select the 20pA range and re-
lease zero check.
7. On the Model 617, press suppress to cancel offset
current and then enable zero check.
8. On the Model 617, set the voltage source for +100V
and select the 200nA current range. Make sure the
voltage source is in standby.
9. Place the Model 617 in the V/I measurement func-
tion by pressing SHIFT OHMS.
10. Turn on the Model 7001 and program it to close
Channels 1!1!1 (Row 1, Column 1) and 1!2!2 (Row
2, Column 2).
11. On the Model 617, disable zero check and press
OPERATE to 100V.
12. After allowing the reading on the Model 617 to set-
tle, verify that it is >1G
Ω
. This measurement is the
leakage resistance (isolation) between Row 1, Col-
umn 1 and Row 2, Column 2.
13. Place the Model 617 in standby and enable zero
check.
14. Turn off the Model 7001.
15. Disconnect the Model 617 from Rows 1 and 2, and
in a similar manner, reconnect it to Rows 2 and 3
(picoammeter high to Row 2 and voltage source
high to Row 3).
16. Turn on the Model 7001 and program it to close
Channels 1!2!2 and 1!3!3.
17. On the Model 617, disable zero check and press
OPERATE to 100V.
18. After allowing the reading on the Model 617 to set-
tle, verify that it is >1G
Ω
.
19. Using Table 5-2 as a guide, repeat the basic proce-
dure in steps 13 through 18 for the rest of the path
pairs (starting with test #3).
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