LC-37AD1E (serv.man9). troubleshooting table - Sharp TV Service Manual (repair manual). Page 10

Check if the internal/external 
switching relay (RY3901) 
functions correctly.

Is the output signal from the 
1-bit amplifier applied to 
P3903?

Perform checking around 
IC2004, IC3804 and the 1-
bit amplifier.

Are the MUTE circuits 
(Q3804 and Q3805) 
operating?

Is the audio signal applied to 
pin (7) (L-IN) and pin (9) (R-
IN) of P3804?

Perform checking 
around IC3803 and 
IC3808.

Check for the AVC 
System side for output.

Is the audio signal applied to 
pin (13) and pin (20) of 
SC2202 on the Monitor PWB?

Perform checking around Q2012 and 
Q2014 and check the wire between 
Monitor PWB and Audio PWB.

Check if 5V is supplied to the power 
regulator circuit (IC3812 and IC3816) 
and pin (2) of P3804.

Is power supplied to each IC 
on the AUDIO PWB?

Is the audio signal applied 
to pin (13) and pin (15) of 
P3803?

No sound comes out. (Checking with the AVC 
System connected)

Check the connection of the high-voltage 
(pin (2)) wire on the side of the blown 
fuse and check that of the counterpart 
high-voltage (pin (2)) wire of the 
fluorescent lamp on the opposite side.

The backlight does not go on.

Is any of the fuses of 
F7501-F7504, 
F7551-F7553 and 
F7641-F7643 
blown?

Is the control signal applied to 
pin (2) (OFL1) and pin (3) 
(OFL2) of P7506 and P7616?

Is the harness connected correctly 
between the Monitor PWB and 
Inverter-1 and -3 PWBs?

Check the peripheral circuitry of 
IC4501 of the Monitor PWB and 
check the operation of Q7704 
and Q7705.

Is power supplied to each 
Inverter PWB?

Check the wire connecting the Inverter-1 and -3 PWBs, the 
wire connecting the Inverter-2 and -4 PWBs, the board-to-
board between the Inverter-1 and -2, and the board-to-
board between the Inverter-3 and -4.

Check the 15V output on the 
Power PWB.

Check the inverter 
circuit downstream 
from the blown fuse. 

Check the counterpart 
inverter circuit on the 
opposite side.