17
X-EM21V
5
6
7
8
5
6
7
8
A
B
C
D
E
F
N
o
TDA7491H
V
(IC302) of the POWER amplifier is
defective. Replace the MAI
N
Assy.
N
o
Has undervoltage protection been activated for
TDA7491H
V
(IC302) of the POWER amplifier?
(Is the voltage at Pins 6, 7, 12, and 13 4
V
or
lower?)
Has thermal protection been activated for
TDA7491H
V
(IC302) of the POWER amplifier?
Can the unit restart after this IC is cooled down
using a point cooler?
Check the periphery of the speaker terminals.
Failure in power supply (Because of an error in
SMPS Assy or damage on L6, the supply voltage,
which should be +13
V
, becomes 4
V
or lower.)
N
o
N
G
N
o
N
G
Has the protection circuit for TDA7491H
V
(IC302) of the POWER amplifier been activated
(is the signal level from Pin 2
8
high)?
Has overvoltage protection been activated for
TDA7491H
V
(IC302) of the POWER amplifier ?
(Is the voltage at Pins 6, 7, 12, and 13 20
V
or
higher?)
Check if the voltage at Pins 1 and 2 of C
N
1102 on the
SMPS Assy and of C
N
402 on the MAI
N
Assy is 13
V
.
The SMPS Assy or the connection cable may be
defective and require replacement.
Yes
Failure in power supply (Because of an error in
SMPS Assy, the supply voltage, which should be
+13
V
, becomes 20
V
or higher.) In effect,
there is possibility that other ICs are damaged.
Yes
Yes
Yes
IC302 is defective. Replace the MAI
N
Assy.
Yes
OK
Replace the MAI
N
Assy.
Has overcurrent protection been activated for
TDA7491H
V
(IC302) of the POWER amplifier?
(Is the voltage at Pins 2, 3,
8
, and 9 [for Ch. R]
or 10, 11, 16, and 17 [for Ch. L] 0
V
[short-circuited]?)
OK
Replace the MAI
N
Assy.
A
