Panasonic SA-PT70EB Service Manual page 35

7.1.2. Troubleshooting Guide
Symptom
Unit cannot power up (No
standby LED)
Power on for a while then
trigger "F61"
Power on for a while and
then trigger
"F76"
No audio output to speaker
Checking items
1) Check AC cord
connection
2) Fuse, F1
3) AC inlet, P5701
1) Check Speaker
connections
2) Check pin 21 & pin 22
of IC200 (micro-p)
3) Check +VDD &
feedback circuit
1) Check VDD & SYS6V
at pin 1,2,5 at H2016 of
SMPS P.C.B.
2) Check voltage: –Vp,
FL1 & FL2 at pin 15,
12 & 13 of H2016 (FL
no display)
3) Check Pin 2 of
Switching regulator,
IC106 (For DVD + 5V &
+3.3V)
4) Check E of Q107 (For
M+9V)
1) Check O/P of Digital
Amplifier IC (Pin 28, 31,
36 & 39, 36)
2) Check I/P to Digital
Amplifier IC (Pin 6, 8,
16, 18)
3) Check supply to Digital
Amplifier IC (IC403,
IC404, IC405) , VDD
(Pin 21)
4) Check DAP IC I/P (Pin
28, 30, 31)
5) Check DAP IC, IC401
(Pin 40 to 52)
6) Check speaker
connection
Possible Fault(s)
1) Faulty AC cord (No Power)
2) Fuse, F1 blow (open circuit)
3) AC inlet, P5701 solder crack, dry-
joint etc
4) L5701 and/or L5702 open circuit
5) TH5702 faulty
1) Speakers short-circuit (check
individual channels)
2) Over-temperature
3) Shunt regulator, IC5801 faulty
4) Feedback circuit: PC5720, D5725
faulty
5) Main Transformer faulty, T5701
(Primary circuit)
6) Switching regulator, IC5701 faulty
7) Diode, D5701 faulty
1) Cable/Wire not connected properly
between Main/D-Amp P.C.B &
SMPS P.C.B or broken.
2) Main Transformer, T5701
short/open or broken.
3) Switching regulator, D5802 faulty.
4) Switching Transformer, T2900 faulty
5) L2915/L2916 Open circuit
6) L2910 Open circuit
7) FP2901 open circuit.
8) Switching regulator IC, IC106 faulty
(No DVD +5V/ +3.3V & SW5V)
9) IP100 faulty (open circuit) – No
+12V supply to Q107 (regulator
circuit)
1) Digital Amplifier (IC403, IC404 or
IC405) IC faulty (There is voltage
supply & I/P but no O/P)
2) DAP IC, IC401 faulty (There is
supply to DAP IC & I/P but no O/P)
3) No oscillating signal, X401 faulty
35
Remarks
SMPS P.C.B
Refer to Figure 1
SMPS P.C.B
Refer to Figure 1
a) SMP P.C.B
Refer to
Figure 1
b) Main / D-
Amp P.C.B
Refer to
Figure 2
Main / D-Amp
P.C.B
Refer to Figure 2