Service manual

Page 25 of 64
4-4 Audio board trouble shooting
4-4-1 DC power circuit
4-4-2 Audio circuit
OK
Check sound mode select
signal:
J635 Pin1=L level?
Q603 C electrode=12V?
Measure Pin 7/8 input
waveform at J55,right?
Check Pin11/15(U675)
have signal?
Check U675 Pin31/28 and
Pin27/24 have signal?
Check the
internal/external speakers
OK
Check J55 is tight
enough or short?
Repair it
Check the coupling Capacitance and inductance.
Check U675 relevant
circuit or replace U675.
Replace speakers
Check audio input
signal
Check sound mode select
signal:
J635 Pin1=H level?
Q603 C electrode=0V?
And the relay “ON”
OK
NG
OK
NG
NG
OK
NG
OK
NG
Internal mode
External mode
OK
Check the wire
from
P602 is tight
enough?
NG
Measure input DC at P602:
Pin1/2＝12V?
Pin3/4＝GND
Measure input DC at U675(TA2024):
U675 testing point＝12V?
U675 Pin25/26＝12V?
OK
Check whether have short or open
+12V
Measure L603,L604,L605,L606=10UH?
And check the waveform(sine wave).