Keithley 7077, Instruction Manual

Page: 42 / 62

Service Information
4-4
tamination, always grasp the card by
the handle and side edges. Do not touch
the card edge connectors, board surfac-
es, or components. On plugs and recep-
tacles, do not touch areas adjacent to the
electrical contacts.
NOTE
Failure of any performance verification
test may indicate that the matrix card is
contaminated. See paragraph 4.2 for card
cleaning instructions. If the test still fails
after cleaning, clean the backplane (see
the Switching Matrix Instruction Manual).
4.4.1 Environmental conditions
All verification measurements should be made at an ambient
temperature between 18
°
and 28
°
C and at a relative humidity
of less than 70%.
4.4.2 Recommended equipment
Table 4-1 summarizes the equipment necessary for perfor-
mance verification and an application for each unit.
NOTE
Do not use the Model 7070 Universal
Adapter Card as an extender card to verify
performance of the Model 7077. The
Model 7077 must be installed in the
switching matrix.
Table 4-1
Verification equipment
Description
Keithley model or
part number
Specifications Applications
DMM
Electrometer with voltage source
Nanovoltmeter
Triax cable (unterminated)
Low thermal cable (unterminated)
Model 2000
Model 6517
Model 182
Model 7025
Model 1484
100
Ω
, .008%
20pA-200pA, 1%
100V source, .15%
2mV, 0.015%
—
—
Path resistance
Offset current path isolation
Contact potential
Offset current
Contact potential
4.4 Performance verification
The following paragraphs discuss performance verification
procedures for the Model 7077, including path resistance,
offset current, contact potential, and isolation.
WARNING
The performance verification proce-
dures contained in this section are in-
tended for use by experienced service
personnel. Do not perform these proce-
dures unless qualified to do so. Failure
to recognize and observe normal safety
precautions could result in personal in-
jury or death.
The procedures described in this section are lengthy due to
the large number of row and column combinations checked.
As an alternative to this extensive testing, it may be desirable
to check only those paths that are going to be used, or those
that are suspected of being faulty.
With the Model 7077's backplane jumpers installed, the per-
formance verification procedures must be performed with
only one matrix card (the one being checked) installed in a
Model 707/708 Switching Matrix. The switching matrix
must not be daisy-chained to another switching matrix.
These conditions do not apply if the Model 7077's backplane
jumpers have been removed.
CAUTION
Contamination will degrade the perfor-
mance of the matrix card. To avoid con-