Maintenance
be checked at the connectors at each end of the board.
Table 7-1 lists the ouptut voltages that shoud be
checked.
Symptom Repeated blowing of fuses indicates a
faulty power supply or other boards:
•
Disconnect the various wiring harnesses or re-
move boards and check for short circuits.
7.8.4 Micro DIN board
•
The micro DIN board contains several ICs and dis-
crete components for interfacing and protection.
Failures are unlikely unless caused by external
overloads. The BIT will test the micro DIN board to
some degree.
Symptom Improper communication with external
equipment via micro DIN or BNC connectors:
•
Check for broken or bent connector pins or exter-
nal wiring.
•
Check for defective BNC or micro DIN board.
Table 7-1
Power supply checks
Test
Output
point
voltage
J102-1
+14.6VDC
J102-4
+6VDC
Notes:
1. Tolerance is measured with output at 60% rated load.
2. Ripple/noise is measured by using a 12-inch twisted wire terminated with a 47µF capacitor.
7-16
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7.8.5 Backplane board
The backplane board interfaces plug-in relay cards to
the digital board. If communication through the back-
plane board is faulty, check the cards and the condition
of the card edge connectors on the backplane board.
Symptom Incorrect identiÞcation of relay cards
plugged into backplane:
•
Symptom Test circuit conÞgurations not functioning
properly:
•
•
7.8.6 BNC board
The BNC board contains only passive components.
Mechanical components include the power switch and
BNC connectors. The only signal cable from the BNC
board carries BNC I/O to the micro DIN board. Fail-
ures are unlikely.
Rated
Tolerance
load
Ripple/noise
±5%
1.67A
100mV
±3%
2.5A
50mV
Move the affected relay card into the other back-
plane slot. If it is correctly identiÞed, suspect the
backplane board. If not, suspect the relay card.
Defective or improperly seated relay cards.
Defective backplane board.
Referenced to J102-2
Referenced to J102-3,
adjustable