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TM 11-6625-2965-14&P
more useful to trace the loop from the series reg-
failures occur more often at the higher power
ulator backwards a stage at a time, since loop
levels.
Table 5-4. High Output Voltage Troubleshooting
STEP
ACTION
RESPONSE
PROBABLE CAUSE
a. Output voltage
b. Output voltage
remains high.
decreases.
Check turn off of series
regulator by shorting Q4
emitter to collector.
a. Series regulator Q7
(or Q6) shorted.
b. Remove short and proceed
to Step 2.
1
2
Check turn on of Q4 by
disconnecting collector
of Q3.
Check turn off of Q3 by
disconnecting collector
of Q1A.
a. Output voltage remains high.
b. Output voltage decreases.
a. Output voltage remains high.
b. Output voltage decreases.
a. Q4 open.
b. Reconnect lead and pro-
ceed to Step 3.
3
a. Q3 shorted.
b, Check Q1A for short,
Q1B for open. Check for
open strap between A6
and A8.
Check R10 for
open.
Table 5-5.
Low Output Voltage Troubleshooting
STEP
ACTION
RESPONSE
PROBABLE CAUSE
1
Check turn on of Q7
(and Q6, if included)
by opening the emitter
of Q4 .
a. Output voltage remains low.
b. Output voltage increases.
a. Q7 (or Q6) open.
b. Reconnect lead and pro-
ceed to Step 2.
2
Eliminate the current
limit circuit as a source
of trouble by discon-
necting the anode of
CR16.
a. Output voltage increases.
a. Q10 shorted, R81 defec-
tive.
b. Output voltage remains low.
b. Reconnect lead and pro-
ceed to Step 3.
3
Check turn off of Q4 by
shorting Q3 emitter to
collector.
a. Output voltage remains low.
b. Output voltage increases.
a. Q4 shorted.
b. Remove the short and
proceed to Step 4.
5-11