Service Information
4-7
Isolation tests
These tests check the leakage resistance (isolation) between all HI and LO inputs for each
channel and from the HI and LO inputs to chassis ground. In general, the test is performed by
applying a voltage (60V) across the connections and then measuring the leakage current. The
isolation resistance is then calculated as R = V/I. In the following procedure, the Model 6517A
Electrometer functions as a voltage source and as an ammeter. In the R function, the
electrometer internally calculates the resistance from the known voltage and current levels and
displays the resistance value.
Perform the following steps to check isolation:
NOTE
To perform this test, you must custom-wire a cable to connect to the scanner card
connections.
1.
Turn off the Model 2000-20 Multimeter if it is on and remove the scanner card.
2.
Remove any jumpers or test leads connected to the card.
3.
Turn on the Model 6517A Electrometer and allow the unit to warm up for two hours
before testing.
4.
Connect a 4 in. length of Teflon-insulated #22AWG stranded wire to every HI and LO
input and output on the scanner card (connectors J1035 and J1036). Mark the free end
of each wire so you can identify the wires when the scanner card is installed.
5.
With the power off, install the scanner card in the multimeter.
6.
Connect the electrometer to OUT A HI and LO of the scanner card as shown in
Figure 4-3
Connections for same-channel isolation tests
HI
LO
Channel 1
HI
LO
Channel 2-9
Channel 10
HI
LO
Channel 11
HI
LO
Channel 12-19
Channel 20
HI
LO OUT A
OUT B
HI
2-Pole
4-Pole
Model 2000-SCAN-20
HI
Model 6517A
V-Source HI
(Red)
Banana to
Banana
Cable
Com
(Ground Link
Removed)
Unterminated to
Banana Cable
V-Source LO
Model 6171
Triax Adapter
Model 7025
Unterminated
Triax Cable
Source V and
Measure V/I
LO
Summary of Contents for 2000-SCAN-20
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Page 12: ...1 General Information General Information ...
Page 17: ...1 6 General Information ...
Page 18: ...2 CardConnections andInstallation CardConnec tionsand Installation ...
Page 35: ...2 18 Card Connections and Installation ...
Page 36: ...3 Operation Operation ...
Page 51: ...3 16 Operation ...
Page 52: ...4 Service Information Service Information ...
Page 63: ...4 12 Service Information ...
Page 64: ...5 Replaceable Parts Replace ableParts ...
Page 67: ...5 4 Replaceable Parts ...
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Page 74: ...A Specifications Section A Specs 7 8 03 4 32 PM Page 1 ...
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