Trou Bleshooti; Power Supply Section; Audio Section - Sansui AU-7700 Service Manual

GAU
-r7oo
4.
TROU BLESHOOTI
NG CHART
4-1. Troubleshooting
on
Power Supply
Symptom
Check Point
1. No
power supplied
to
each section
1-1.
lndicator lamp
for power not
lighted
Section
1-2.
lndicator
4-2. Troubleshooting
on
Audio
Section
"1
.
Rel
ày, RL01
inoperative
(protector
circu
it
inoperative)
2.
Bias
current not adiustable
to *45mA
by
VR03
(L-ch)
or
VR04 (R-ch)
on
t-2097
Center Voltage
not
adiustable
(L-ch) or VR02 (R-ch)
on
F-2097
to 0V by
VR01
Cause
& What
to
Do
Power
supply cord open
lmperfect contact of power switch,5701
Power
f
use,
F701
open
Defective power
transformer, T701
F07
on
t-2097 open
Defective
D21
on
F'2097
lmperfect contact of voltage selector,
PUOl
F05
or
F07
on
F2097
open
Defective D17
or
D19
on
t-2097
Defective power
transformer, T701
F01
(or
F03)
on t-2092 open
Defective D01, D03,
D07
or
D09
on
t-2092
Defective TR09, TR11, TR13
or TR15 on
t-2092
F07
on
F-2097
open
Defective
D21
on t-2097
Defective D13, D'I5
or
D25
on t'2097
Defective TR29, TR31
or TR33
on
F-2097
Defective reluy,
RL01
on
F-2097
Defective TR21
or
TR23
(TR22 or
TR24)
o
n
F
'2097
Defective TR25
or
TR27
(TR26 or
TR2B)
on
t-2097
Defective TR05 or
TR07 (TR06
or
TR0B)
o
n t'2097
Defective
VR03 (VR04) on
F'2097
Defective
TR05
(TR06)
on
F-2097
Defective
VR01 (VR02) on
F'2097
lamp
for power
Iighted
+41Y not
supplied
to
collector
trans
istors
(+
41V
,
TR21
,-TR24,
1.
2.
3.
4.
5.
6.
7.
B
1)
on each power
-
41V
,
TR25
-
TR2B)
2)
+24V not
supplied to
terminal
not supplied
to terminal
tr on
@
and
-2sV
F-2092
L_;
10.
11.
12.
13.
V,
\t
3.
10
L-;;
1.
2.
3.
5