Agilent Technologies E3630A Manual De Funcionamiento Y Servicio página 94

SYMPTOM
The +20V supply must operate properly before troubleshooting the -20V supply.
High output voltage 1. Attempt to turn off Q1 by
(higher than rating) shorting emitter-to-base
of Q1.
2. Measure voltage at
base of Q4.
Low output voltage 1. Measure voltage at the
(lower than rating) base of Q4.
2. Eliminate current limit
circuit as a source of
trouble by disconnecting
anode of CR7.
3. Measure voltage at
pin 3 of U2.
STEP
Set output voltage at 12V+0.5V.
1 Measure pin 1 of U14.
2 Measure pin 1 of U13.
3 Measure pin 1 of U11.
STEP
Set output voltage at -12V-0.5V.
1 Measure pin 7 of U14.
2 Measure pin 1 of U12.
3 Measure pin 1 of U10.
Table A-7. +6V Supply Troubleshooting
STEP - ACTION
a. Output voltage remains high.
b. Output voltage becomes near zero
a. Measured voltage is more than
b. Measured voltage is less than
a. Measured voltage is less than
b. Measured voltage is more than
a. Output voltage increases.
b. Output voltage remains low.
a. Measured voltage is near
b. Measured voltage is zero volt.
c. Measured voltage is near
Table A-8. +20V Preregulator/Control Circuit Troubleshooting
ACTION
a. Measured voltage is -12V.
b. Measured voltage is near
a. Measured voltage is near +1V
b. Measured voltage is near 0V.
a. Measured voltage is near +1V
b. Measured voltage is near 0V.
Table A-9. -20V Preregulator/Control Circuit Troubleshooting
ACTION
a. Measured voltage is -12V.
b. Measured voltage is near
a. Measured voltage is near +1V
b. Measured voltage is near
a. Measured voltage is near +1V
b. Measured voltage is near 0V.
RESPONSE
volt.
-0.6V.
-0.6V.
-0.6V.
-0.6V.
-0.7V.
+0.7V.
RESPONSE
+4.3V.
RESPONSE
+4.3V.
+4.3V.
A-10
PROBABLE CAUSE
a. Q1 shorted.
b. Remove short and proceed to
step 2.
a. Check for defective Q4.
b. Check for open CR6, R11 and
check for defective U2A.
a. Check for open Q1, Q6, R25, or
CR5.
b. Proceed to step (2).
a. Check for U2B defective.
b. Reconnect lead and proceed to
step (3).
a. Check for defective U2A.
b. Check for CR9 and CR10 shorted.
c. Check for open R29, shorted R11,
or leaky or shorted C5.
PROBABLE CAUSE
a. Proceed to step (2).
b. Check for defective U14A.
a. Check for defective U13 or
CR12.
b. Check for open Q11 or R81.
a. Check for defective U11.
b. Check for open Q11 or R82.
PROBABLE CAUSE
a. Proceed to step (2).
b. Check for defective U14B.
a. Check for defective U12 or
CR31.
b. Check for open Q10 or R56
a. Check for defective U10 or
CR27.
b. Check for open Q10 or R55.