Sharp LC-37HV4U Service Manual page 27

TROUBLE SHOOTING TABLE (Continued)
No sound comes out. (Connect to the AVC system and check.)
Is power supplied to each IC
in the audio unit?
YES
Is an audio signal appearing
at pin (8) (L-IN) and pin (10)
(R-IN) of P3802?
YES
Is an audio signal appearing
at pins (10) and (14) of
IC3812 (Audio Output)?
YES
Is an audio signal appearing
at pins (24), (27), (28) and
(31) of IC3812 (Audio
Output)?
YES
Check if RY3801 (for
Internal/External switching) is
operating properly.
The whole screen is whitish (LCD power supply)
Disconnect the FFC from CN4101,
CN4102 and CN4601-CN4604.
(Otherwise it may cause the panel to get
broken.)
YES
Check the power supplies.
Check the power supplies to CN4101
and CN4102 in particular.
YES
Is the voltage of R4114 around 6V?
YES
Check the I/O voltages of IC4103,
IC4105 and IC4106.
NO
Check around the
power regulator circuit
(IC3809, IC3810).
NO
Is an audio signal
appearing at pins (13)
and (20) of SC2202 in
the main unit?
YES
Check around Q2012 and Q2014 and check the
wire connected between the main unit and
audio unit.
NO
Are Q3812 and Q 3813
(MUTE Circuits)
operating?
NO
Check D3828-D3831
for short-circuiting and
check the circuits
around IC3812.
Check the performance of Q4101
NO
and Q4112 and check the
resistances around IC4102.
27
NO
Check for output from the
AVC system side.
NO
Check IC3801, IC3803,
IC3804-IC3807, and
IC3811 for I/O signals.
LC-37HV4U
LC-37HV4D