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4.6.5 Path resistance verification
The following paragraphs discuss the equipment, connec-
tions, and procedure to check path resistance. Should a par-
ticular pathway fail the resistance test, the relay (or relays)
for that particular crosspoint is probably defective. See the
schematic diagram at the end of Section 5 to determine
which relay is defective.
NOTE
The following procedure verifies the resis-
tance of the HI signal path. To verify the
resistance of the GUARD path, modify the
cable of Figure 4-5 to connect the inner
shield to the banana plug and have no con-
nection to the triax center conductor.
Recommended equipment
• Model 196 DMM
• 7078-TRX-T triax tee adapters (3)
• 237-BAN-3 triax to banana cables (4)
Connections
Figure 4-6 shows the connections for the path resistance
tests. The Model 196 is to be connected to the row and col-
umn jacks using Model 237-BAN-3 triax/banana cables.
These cables differ from the one in Figure 4-5 in that the
inner shield and center conductor are not connected together.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
7078-TRX-T
Triax Tee Adapters
237-BAN-3
Triax/Banana
196 DMM
Figure 4-6
Connections for path resistance verification
Service Information
7174A
KEITHLEY
8 x 12 LOW
CUR R ENT MATRIX
SIGNAL
COLUMNS
200V PK
200V PK
GU
RD
A
200V PK
ROWS
B
C
D
E
Triax
F
G
H
WARNING:
!
TIGHTEN MOUNTING SCREWS
TO ENSURE PROPER
CHASSIS GROUND
7174A Matrix Card
4-9
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