Series Regulator Troubleshooting, High Voltage Condition - HP 6269B Operator’s, Organizational, Direct Support And General Support Maintenance Manua L

Table 5-5. Series Regulator Troubleshooting, High Voltage Condition
ACTION
STEP
These tests should be made with
1 Check turn-off of series
regulator transistors A4Q103
through A4Q108 by shorting
base (TP101) to emitter
(TP103).
2 Check turn-off of driver
A4Q102 by shorting base
(TP100) to emitter (TP101).
3
Check conduction of error
amplifierA4Q101 by connect-
ing base (TP45) to cathode
of CR45 (TP67) through a
100 Ω resistor.
4
Check conduction of error
amplifier Q42 by connecting
base (TP44) to cathode of
CR45 (TP67) through a 1K Ω
resistor.
s Check turn-off of mixer am-
plifier Q41 by connecting
base (TP40) to +11 volt sup-
ply (TP66) through a 1K Ω
resistor.
6 Check turn-off of constant
voltage comparator Z 1 by
shunting R 1 with a 10K Ω re-
sistor, or by installing a
10K Ω resistor in R1 position
if resistor is not installed
in the supply.
Table 5-6. Series ReguIator Troubleshooting, Low Voltage Condition
STEP ACTION
These tests should be made with external source connected as described in Table 5-4, Step 3.
1 Check conduction of series
regulator transistors A4Q103
through A4Q108 by connect-
ing base (TP101) to +11 volt
supply (TP66) through a 100
ohm resistor.
RESPONSE
external source connected as described
a. Output voltage remains high.
b. Output voltage decreases.
a. Output voltage remains high.
b. Output voltage decreases.
a. Output voltage remains high.
b. Output voltage decreases.
a. Output voltage remains high,
b. Output voltage decreases.
a. Output voltage remains high.
b. Output voltage decreases.
a. Qutput voltage remains high.
b. Output voltage decreases.
RESPONSE
a. Output voltage remains low.
b. Output voltage rises.
5-13
TM 11-6625-2958-14&P
PROBABLE CAUSE
in Table 5-4, Step 3.
a. One or more of A4QI03
through A4Q108 shorted
or A4CR105 shorted.
Check A4R150-A4R155.
b. Remove short. Proceed
to Step 2.
a. A4Q102 shorted.
b. Remove short. Proceed
to Step 3.
a. A4Q101 open.
b. Remove resistor. Pro-
ceed to Step 4.
a. Q42 open.
b. Remove resistor. Pro-
ceed to Step S.
a. Q41 shorted.
b. Remove resistor. Pro-
ceed to Step 6.
a. Z1 defective, R110
shorted.
b. R23 open, open strap
between A 1 and A2,
A5R121 or A5R122 open.
PROBABLE CAUSE
a. A4Q103 throughA4Q108
open and/or A4R150
through A4R155 open,
A4CR106 shorted.
b. Remove resistor. Pro-
ceed to Step 2.
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