Keithley 7077, Instruction Manual

Page: 43 / 62

Service Information
4-5
4.4.3 Path resistance tests
NOTE
Refer to the performance verification
overview (paragraph 4.4) prior to perform-
ing this procedure.
1. Remove all power from the switching matrix and
switching matrix cards.
2. Install the Model 7077 Matrix Card in the switching ma-
trix.
NOTE
Install the Model 7077 Matrix Card in slot
one of the Model 707/708 Switching Ma-
trix.
3. Connect all column terminals (columns 1 through 12) of
the Model 7077 together (Figure 4-2) forming one com-
mon terminal.
4. Set the Model 2000 to the 100
Ω
range for
Ω
4 measure-
ments.
5. Connect the four test leads to the INPUT and SENSE
Ω
4 WIRE inputs of the Model 2000. Make sure the
Model 2000 is set appropriately for front panel or rear
panel inputs.
6. Short the four test leads together and zero the Model
2000. Leave zero enabled for the entire test.
7. Connect the Ohms HI and Ohms Sense HI leads from
the Model 2000 to the common terminal (refer to step
3). Make the physical connections at columns 1 through
12 as shown in Figure 4-2.
8. Connect the Ohms LO and Ohms Sense LO leads from
the Model 2000 to the high terminal (marked H in Fig-
ure 4-2) of ROW A.
9. Turn on the switching matrix and check the high termi-
nals’ path resistance.
A. Program the switching matrix to close crosspoint
A1. Verify that the resistance of this path is <1.5
Ω
.
B. Open crosspoint A1, and close crosspoint A2. Verify
that the resistance of this path is <1.5
Ω
. Repeat this
procedure for the remainder of row A’s high termi-
nal column paths (columns 3 through 12).
10. Turn off the switching matrix and connect the Ohms LO
and Ohms Sense LO leads from the Model 2000 to the
low terminal (marked L in Figure 4-2) of ROW A.
11. Turn on the switching matrix and check the low termi-
nals’ path resistance.
A. Program the switching matrix to close crosspoint
A1. Verify that the resistance of this path is <1.5
Ω
.
B. Open crosspoint A1, and close crosspoint A2. Verify
that the resistance of this path is <1.5
Ω
. Repeat this
procedure for the remainder of row A’s low terminal
column paths (columns 3 through 12).
12. Repeat steps 8 through 11 for the remainder of the ma-
trix card’s rows (rows B through H).