IEC 30 Series - Troubleshooting Guide

SECTION 5
TABLE 5-1. TROUBLESHOOTING GUIDE
Symptom/Step
Possible Cause
Remarks
1.
a.
NO OUTPUT
For all waveform
positions
1.
Output amp disabled.
2. Power supply disabled.
See step 14.
See step 20.
b.
For all waveform
positions except
(offset) dc
Triangle loop stalled. See steps 15
and 4b.
c. No sine waveform
output
Sine shaper disabled.
See step 21.
d.
No square output
1.
Short to ground between CR19 cathode and Q7
or Q8 base.
2.
Open CR19
or CR21, R61, R62 or R63.
3.
Open R64 or R65, Q7 or Q8.
e.
No offset capability
S4 not functioning (always closed).
f.
No variable pulse
(33, 34)
1.
Variable pulse circuit disabled.
2.
Wiper of R248 shorted to ground.
See step 24.
g.
No sweep (F34)
1.
Swi tch not in SWP mode position.
2.
Logic "0" from S6-2B wiper. See step 22.
2.
NO SYNC OUT,
Loop Functioning
1. Open circuit between TP13 and Sync Out BNC.
2.
Short to ground between R44 and Sync Out BNC.
3.
NO
FREQ ANALOG
OUT (F34)
1.
Faulty IC-17.
2.
Open circuit between IC17-6 and Analog Out
BNC.
4.
a.
OUTPUT LEVEL
Improper
Low
amplitude 1.
Output amp faulty.
2.
Misadjusted R166.
3.
Failure in attenuator S5.
4.
Failure in LEVEL potentiometer (R107).
See step 14.
Check atten-
uator calibra-
tion.
b.
Large d-c Offsets
1.
S4 failure.
2.
Misadjusted R119.
3.
Output amplifier faulty.
See part 14.
5-3