Realistic STA-7 - Troubleshooting; Troubleshooting Common Issues

7.
TROUBLESHOOTING
)
I
I
I
Symptom
Cause/Remedy
1)
No
output
1)
Faulty AC
power
cord
*Replace
the
cord.
2) Defective
power
switch
*Replace
the switch.
3)
Broken wire in
the
power
transformer
*
Replace
the
transformer.
2)
Pilot lamps do not light. 1)
Broken lamp(s)
(PL7O2-7O5l.
*Replace
the
lamp(s).
2) Open in the
power
transformer tertiary winding
*
Replace the transformer.
3)
Blown
fuse
in tertiary
winding
(1.5
A)
(F3)
*Replace
fuse.
3)
Pilot
lamps light but no speaker output 1)
Defective capacitor C505
or
506
*
Replace
the
defective capacitor(s).
2) Defective diode
D501-504
*Replace
the
defective diode(s).
3) Defect in the
power
transformer secondary
winding
*Replace
the
power
transformer.
4) Blows
fuse.
1)
Defective diode
D501-504
in the
rectif
ier circuit
*Replace
the
defective diode.
2) Short-circuit
in
the
rectifier
circuit.
*Remove
the short.
3) Short-circuit
in
power
lC
circuitry
lC4O1
or 402
*Replace
circuit
and/or
replace the defective transistor(s).
5-1) No
output one
channel
with
VOLUME
at
maximum and BALANCE
at center,
when
a test signal
is
applied
to
the terminal of
non-operating chan-
nel of
the
BALANCE control
VR302.
1
)
Defective transistor TR 301
-304
or
1C401
,
4O2
*Replace
the defective transistor(s) or
lC.
2) Defective
resistor
or
capacitor
of
TONE
or
MAIN AMP circuit
"Replace
the
defective
part(s).
5-2l
No
output
when
a
test signal is applied
to
the
input
terminals.
1)
Defective transistor,
resistor
or capacitor of
PRE AMP
circuit
*Replace
the
defective
part(s).
2) Defective
MONO/Stereo or TAPE MONitor
switch
*Replace
or
repair
the switch(es).
3)
Defective Selector switch
*Replace
the Selector
switch.
6) Speaker
works normally
but
headphone
does not work.
1)
Defective
R423
(left)
or
R424
(right)
*Change
it.
7)
All the inputs
work normally except
"AUX"
input.
1)
Poor contact
in
"AUX"
input
jack
*Repair
or
replace it.
2)
Poor
contact
in selector switch
*Repair
or replace the switch.
8)
"PHONO"
input
not
operative 1)
Poor
contact in "PHONO"
input
jack
*Repair
or
replace it.
2)
Faulty
selector switch
*Repair
or
replace
the switch.
fi
-21
-