Table B-2
Troubleshooting Procedure Chart (Continued)
PROBLEM
PROBABLE CAUSE
RECOMMENDED REPAIR
3. Emergency unload
1.
Emergency
unload
condition
1. Refer
to
Recommended Repair column, Problem
14.
relay, K 1 , on Servo being activated prevents
K1
PCBA, does not relay from engaging
during
engage.
purge
cycle.
2.
Defective relay or defective
2.
Replace relay
K1
(Servo PCBA).
If
still
not engaging, check logic level at
relay engage
circuit.
J202-32.
If
low, relay driver
circuit
Is defective; replace the Servo PCBA.
If
J202-32
is
high and does not go
low
when going Into purge cycle,
replace the
Logic
PCBA.
3.
-20v
dc at J212-3
out
of
3.
Check the
following:
tolerance.
a.
Check fuses
F1
, F2, F3, and F4. Refer
to
Power Supply assembly
drawing
103581
for fuse location.
b.
Refer
to
Servo PCBA drawing
102811
for test point locations. Use an
oscilloscope or digital voltmeter
to
check voltages as follows.
Test POint Voltage
TP4
+
5v
dc ± 0.25v dc
TP12
-5v
dc ± 0.25v
dc
TP21
+ 10v dc ± 0.8v de
TP25
-10v
dc
±0.8v
dc
c.
If
voltage at TP4
is
incorrect, adjust variable resistor
R158.
If
voltage at TP12
is
incorrect, adjust variable resistor
R167.
Both
resistors are shown at the upper
left corner of drawing 102811.
d.
If any voltage cannot be correctly adjusted, check the input voltages
at J212, as follows.
J212-8
+
10v dc
-0.5
+5vdc
J212-11
+
20v
de
-3.0
+5vdc
J212-3
-20vdc
-5.0
+3vdc
e.
If
any voltage specified in Step 3d is not present, replace the power
supply; otherwise
go
to Step 3f.
1.
If
one
of
the voltages
is
not correct, disconnect all boards that are
powered from the Servo
PCBA.
If
voltages are correct after boards are
disconnected, begin reconnecting boards one at a time
until
an
incorrect
voltage is measured. Replace board causing the problem.
g.
If voltage at
TP21
is incorrect, check
026
on the heatsink.
If
026
is
defective, replace it. If
026
checks good, replace the Servo PCBA.
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