Pioneer SC-37 Service Manual page 62

1
QQ
3 7 63 1515 0
Amplifier Diagnosis without Current Applied
A
The most common symptom of the power amplifier failure is the destruction of the power amplifier output stage or the power amplifier power
circuit due to the heavy load, which is, for example, caused by short of the speaker terminal or the use of the non-guaranteed low impedance
speaker.
If the protection circuit immediately shuts it down immediately after the current is applied, it is highly likely that it is the above symptom.
The procedure to diagnose/repair without applying current is shown below.
Before starting the diagnosis, wait for
three minutes until the electricity is
discharged.
Yes
Diagnosis of the power amplifier output stage (The example below uses the
B
wiring No. of FLch.)
Check that the MOSFET is not shorted (Ex.) Q4100, Q4101
Check that the gate resistance is not damaged (Ex.) R4148, R4149
Check that the gate diode is not damaged (Ex.) D4101, D4102
Check that the gate drive transistor is not damaged
(Ex.) Q4102, Q4103, Q4104, Q4105
Diagnosis of the output stage power supply (B REG Assy)
Check that the fuses FU61 and FU62 are not burned out
Check that the transistors Q7300 and Q7301 are not damaged
Check that the diodes D7308 and D7310 are not damaged
C
Diagnosis of the driver power supply (ICE REG Assy)
Check that the fuse FU15 is not burned out
TE
L 13942296513
Diagnosis of the power amplifier drive circuit (The example below uses the
wiring No. of FLch) (When the driver power supply has an error, it is suspected
that the power amplifier drive circuit also has an error)
Check that the driver IC is not damaged (IC4101)
Check that the L and R connected in series to the power supply are not
damaged (L4104, R4147)
D
E
www
F
62
1
http://www.xiaoyu163.com
2
x ao
y
. i
2
http://www.xiaoyu163.com
3
8
Q Q
3 6 7 1 3
u163
.
SC-37
3
4
2 9 9 4 2 8
1 5 0 5 8 2 9 9 4
m
co
4
9 9
2 8 9 9