Agilent Technologies E3630A Manual De Funcionamiento Y Servicio página 92

STEP ACTION
1 Check output voltage of +20V
supply.
2 Check output voltage of -20V
supply in fixed tracking ratio
mode.
3 Check output of +6V supply.
STEP ACTION
1 Check +12V bias.
2 Check -5V reference.
3 Check -12V bias.
SYMPTOM
High output voltage 1. Attempt to turn off Q9 by
(higher than rating) shorting emitter-to-base
of Q9.
2. Measure voltage at
base of Q5.
Table A-3. Initial Trobleshooting Procedure
RESPONSE
a. Normal
b. Zero volts
c. Output voltage lower or
higher than rating
a. Normal
b. High, low, or zero out-
put voltage.
a. Normal
b. High, low, or zero out-
put voltage.
Table A-4. Bias and Reference Voltage Check
RESPONSE
a. Normal (+12V ± 5%)
b. Voltage high
c. Output voltage lower or
higher than rating
a. Normal (-5V ± 2%)
b. Voltage high
c. Voltage low
a. Normal (-12V ± 5%)
b. High voltage
c. Low voltage
Table A-5. +20V Supply Troubleshooting
STEP - ACTION
a. Output voltage remains high.
b. Output voltage becomes near zero
a. Measured voltage is less than 0
b. Measured voltage is more than 0
a. Proceed to step (2).
b. Check ac line fuse (F1). If blown, proceed to "Open Fuse
Troubleshooting" paragraph. If not blown, check bias
and reference voltages (Table A-4).
c. Check bias and reference voltages (Table A-4).
a. If +20V and -20V outputs are both normal with no load, a
supply might be current limiting under load. To check
this adjustment see steps (l) thru (p) on page A-4.
b. Proceed to -20V supply troubleshooting.
a. If the output of this supply is normal unloaded but its volt-
age falls when loaded, check the current limit adjust-
ment, steps (q) thru (t) on page A-4.
b. Proceed to Table A-7.
a. Proceed to step (3).
b. Check U3 for short.
c. Check U3 for open.
Note: A short within U2, U6, U8, U9 or U14 can cause low
+12V or -12V bias voltages.
a. Proceed to step (3).
b. Check U5 for open.
c. Check U5 and Q2 for short.
a. Proceed to +20V supply troubleshooting, Table A-5.
b. Check U1 for short.
c. Check U1 for open.
RESPONSE
volt.
volt.
volt.
A-8
NEXT ACTION
NEXT ACTION
PROBABLE CAUSE
a. Q9 shorted.
b. Remove short and proceed to step
(2).
a. Check for open CR13 or R36 and
check for defective U6A.
b. Check for defective Q5.