Symptom
Procedure
Probable cause
9. High output unable to be reduced Open Zener diode CR4 . . . . . . . . . .
Replace diode.
to zero.
10. Poor regulation in output (master- Low gain in one of control am-
Check individual stages and replace
plifiers (Q10, Q11, Q12, Q13,
slave stages). (Results of test
as needed.
given in para 6-7.)
Q14, or Q15).
11. Poor regulation in reference sup- Low gain in one of the reference
Check individual stages and replace
as needed.
supply stages (Q16, Q17, Q18,
ply. (This symptom may be
checked by the test given in para
Q19, Q20, or Q21) or reference
5-3b (3).)
Zener diode CR12.
12. Poor regulation with R36 over- Shorted transistor Q7 . . . . . . .
Replace transistor.
Replace transistor.
Shorted transistor Q8 . . . . . . . . . . .
1 3 . Poor regulation with R9 over-
Replace transistor.
Shorted transistor Q9 . . . . . . . . . . .
14. Poor regulation with R47 and R10
overheating.
Filter capacitor C1, C9, C13, C16,
Check for leakage, capacity change,
15. High ripple as measured at the
load terminals.
or C17 are faulty.
or opens.
Note: measured ripple should be
Faulty rectifier doide CR1 or CR2
Unsolder leads to check for open or
0.5
millivolts
rms.
shorts; replace.
or both.
Response time o f c o n t r o l a m -
individual
Check
transistors
for
plifiers not adequate because of
alpha on a suitable tester.
(In-
l o w gain on a stage, or poor
circuit tests may be made. Refer
response on a passing stage.
to applicable transistor manual.)
Loose connections in power supply.
Perform visual check and tighten.
Open in one side of input trans-
Unsolder leads at diodes CR1 and
formed secondary (T2).
CR2 and check continuity at trans-
former secondaries.
5-2
