Tequipment Agilent E361 Serie Manual De Funcionamiento Y Servicio página 26

SYMPTOM
Poor Load Regulation
(Constant Voltage)
Poor Load Regulation
(Constant Current)
Oscillates (Constant Voltage/
Constant Current)
Poor Stability
(Constant Voltage)
Poor Stability
(Constant Current)
Excessive heat
OVP Shutdown
STEP ACTION
1 Check turn off of Q1 and
Q4 by shorting Q9 emitter
to collector.
2 Check turn on of Q9 by
shorting point 1 to -12 V.
3 Check voltage from pin 5
to pin 6 of U9.
STEP ACTION
1 Check turn on of Q1 and
Q4 by disconnecting emitter
of Q9.
2 Check turn off of Q9 by
shorting point 1 to +15 V.
3 Eliminate constant current
comparator as a source of
trouble by disconnecting
anode of CR22.
Table A-3. Overall Troubleshooting (Cont'd)
CHECKS AND PROBABLE CAUSES
a. Refer to "Measurements Techniques" paragraph.
b. Check +10 V reference voltage.
c. Ensure that the supply is not going into current limit.
a. Check +10 V reference voltage.
b. CR1, CR19, CR20, C2, C31 leaky.
c. Ensure that the supply is not crossing over to constant voltage operation.
a. Check C29 and C36 in constant voltage circuit.
b. Check C31 and C33 in constant current circuit.
a. Check +10 V reference voltage.
b. CR27, CR28, CR23, and CR26 leaky.
c. U9 defective.
d. Noisy programming resistor R83.
a. Check +10 V reference voltage.
b. CR24, CR25, CR29, and CR30 leaky.
c. U9 and U10 defective.
d. Noisy programming resistor R85.
a. Check preregulator control circuit. Refer to Table A-6.
b. CR10, CR12, CR15, and CR18 short
a. Check that the front panel OVP Adjust screw control is rotated fully clockwise.
b. Check the overvoltage protection circuit.
Refer to "Overvoltage Protection Circuit Troubles" paragraph or Table A-7.
Table A-4. High Output Voltage Troubleshooting
RESPONSE
a. Output voltage remains high.
b. Output voltage decreases.
a. Output voltage remains high.
b. Output voltage decreases.
a. Input voltage is positive.
b. Input voltage is negative.
Table A-5. Low Output Voltage Troubleshooting
RESPONSE
a. Output voltage remains low.
b. Output voltage increases.
a. Output voltage remains low.
b. Output voltage increases.
a. Output voltage is increases.
b. Output voltage remains low.
a. Q1 or Q4 shorted.
b. Remove short and proceed to step 2.
a. Q9 open.
b. Remove short and proceed to step 3.
a. U9B is defective.
b. Turn down the voltage control fully
counter clockwise. Check the voltage
of U9 pin 1 is 0.
a. Q1 or Q4 open.
b. Reconnect emitter lead and proceed to step 2.
a. Q9 shorted.
b. Remove short and proceed to step 3.
a. Proceed to step 4.
b. Reconnect lead and proceed to step 5.
A-10
PROBABLE CAUSE
PROBABLE CAUSE