IEC 30 Series - Page 48

SECTION 5
Table 5-1. Troubleshooting Guide (Continued)
Symptom/Step
Possible Cause
Remarks
b.
Negative output
« -11 open circuit)
at all times.
1.
2.
Q18,
or VR7 open.
Negative regulated supply not operating.
3. IC9 faulty.
c.
Small offsets only.
1.
IC9 faulty.
2.
Q17
shorted base to emitter or open collector.
d. Clipped waveforms.
1.
Q19 or Q20 open.
2.
IC9 faulty.
I
e. Oscillations.
1. C55 or C53 open.
2. C58
misadjusted.
3.
C56, C59, C57,
or C52 open.
4. Feedback path partially shorted: R166 or R132.
f.
Squarewa ve for all
Waveforms positions,
saturating at both
ends.
Feedback path open: R166 or R132 open.
g. Low amplitude 1. Feedback path shorted or partially shorted: R166,
R132.
2.
Q18
or IC9: low current gain.
h.
Ov Output C58 shorted.
15. TRIANGLE LOOP
INOPERATIVE
a.
Squarewave locked
up @ +3v @ TP16 or
Triangle locked up
@ >+3v @ TP19.
I
1. IC5 faulty.
2.
Q9 or (;/j open.
3.
CRll, CR12, CR13 or CR14 open.
b. Squarewave locked
up at -3v @ TP16 br
Triangle locked up
> -3v @ TP19.
l. IC5 faulty.
2. Q9 or Q6 open.
3.
CR11, CR12, CR13,
or CR14 open.
c.
Squarewa ve locked
up
@ ±3v @ TP16 or
Triangle locked up
"",Ov.
1.
2.
C1, C2, C3, C4, C5, C6, C8, C9, C10,
shorted to common.
IC4
faulty.
or C14
3.
TP9 or junction of R12 and R13 shorted to
common.
5-8