IEC 30 Series - Page 51

SECTION 5
Table 5-1. Troubleshooting Guide (Continued)
Symptom/Step
Possible Cause
Remarks
i.
-5v too low. Q3l, Q32 open.
2l.
SINE SHAPER
FAULTS
a.
Sine Amplifier
no output.
l. IC6 faulty.
2. VRl faulty.
3. C43 shorted.
b. Excessive distortion.
l.
IC6 faulty.
2. Open diode in IC7 or IC8.
3.
CR29, CR30 shorted.
4.
Open
resistor in RlOO or RlOl.
c.
Clipped Waveforms. l.
Open CR29, CR30.
2.
Qll, Ql2, Ql5, Ql6 faulty.
3.
Ql3, Q14 shorted.
22. LOGIC FAULTS
a.
Logic "0" at TP30
in CONT
mode.
l. Open CR53.
2.
Short to ground at CR54, CR68, CR69 or S6-lB.
b.
Logic "0" always at
TP30 in GATE,
BURST and SWP
CONT
modes.
l.
ICl4 faulty.
2.
ICl3 faulty.
3.
S9 faulty.
23.
START-STOP
FAULTS
a.
No Gating.
l. Q52 open.
2.
Open
circuit between E47 and TP25.
b.
Incomplete last
Triangle Cycle.
CR56 open.
c.
Loop Stalled
Negative @ TPl3.
l.
Q52, Q53 or Q54 shorted.
2. Q55 open.
d.
Loop Stalled
Positive @ TPl3.
CR58 shorted.
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