SERVICE MANUAL
Document No
Date of Origin
Date of REV
51-L-DSR004
98-10-21
PAGE REV.
0
PAGE
33 /102
S-00-005(96.03.27)
REV.1
7-7. Audio
7-7-1. Check pin 5 and 8 of U700 for audio signal with an oscilloscope
as below when STB's channel
is locked.
if there are no audio
signal,
goto 7-7-5
figure 7-7-1. Audio signal wave form
7-7-2. Check pin 1, 7 of U701 for amplitude
audio signal and if there are
no signal,
check VCC voltage
pin 8 and replace
IC's if VCC has no
problem.
7-7-3. Check the test point TP944, TP946. if there is no audio signal
then check VCC Voltage
pin 55. if there is 12V then Replace
the U901 IC's
7-7-4. Check the test point TP901, TP902, TP908, TP909. if there is no
audio signal then continually
Check and find PCB pattern's
open or
short and defective
component
to replace
R943,R946
and L900 to L905
7-7-5. check control
signal pin 1 to 4 of U700 and Replace
U700 IC's if
control
signal is normal,
else replace
mainboard.
7-7-6. if there are no audio signal when after Replacing
U750 IC's then
Keep tracing
the signal path referring
to the schematic
diagram
and
find PCB pattern's
open or short and defective
component
to replace.
10mS /
500mV div