IEC 30 Series - Page 49

SECTION 5
Table 5-1. Troubleshooting Guide (Continued)
Remarks
Possible Cause
Symptom/ step
See step 20.
and triangle wave
at Ov.
Power supply disabled.
d.
Both squarewave
16.
VLS
FAULTS
a.
TP16 @ +3v and 1. qJ open collector or base-emitter short.
TP13 @ +5v always.
2. IC5 -9 does not go to + logic level (~3v): faulty
IC or no input.
3.
(!) open.
4.
(;{J or Q10 shorted.
5.
TP19 open circuit.
6. TP13 open.
b.
TP16 @ -3v and 1. Q9 shorted.
TP13 @ -5v always.
2.
IC5-9 does not go to - lOgic
level (~1 v). or
no input.
3. CR17 open.
4.
TP19 jumper open circuit.
5.
TP13 jumper open circuit.
17.
FOLLOW AMPLIFIER
1.
IC4 faulty.
a.
TP19 @ +5v.
2. Q4 shorted (drain to source)
3. Q21 or R29 open.
b.
TP19 @ more
1. IC4 faulty.
negative than -5v.
2.
Q4 open.
3. Q21
shorted.
1.
IC4 faulty.
and -3v.
c.
TP19 between +3v
2.
Short to ground.
from E49 to S3.
18.
CURRENT CONTROL
DISABLED
1.
Q2 open.
and short TP17 to
ground for test.
a.
Set FREQ dial @ 3.0
2. IC2 faulty.
Voltage @ CR9
cathode < 330mv
See step 19.
Voltage @ CR4
3.
Voltage across R15 less than 5. 8v: (a) IC1 faulty
or Q1 open; (b) voltage at TP8 improper.
cathode +5v.
FREQ Control faulty.
5-9