LC-42XD1E (serv.man5). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 18

LC-42XD1E/RU

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Note: The SD signal (576i 480i) alone passes through the FRC circuit. (The HD signal does not go through.)

                         

                        

                       

Does the image appear with the HD sig-
nal, but not with the SD signal?

Does anything unusual (which or black-
ish screen, block noise, for example) 
appear on the screen?      

Does the image look unusual with the 
power switch turned on?    

YES

YES

YES

Is the power supplied to IC3301 (FRC)?
Is there the FRC-IN signal input at pins 
(142) and (13) of IC3301? 
Check the soldering condition. 

Is there the specified RESET-A signal 
input at pin (39) of IC3301 (FRC)? 
(60 ms delay design)     

Check the connection between pin 
(R22) of IC3002 (V-PRO.) and pin 
(142) of IC3301 (FRC) as well as that 
between pin (N20) of IC3302 and pin 
(13) of IC3301    

YES

NO

Replace IC3301 (FRC).

Check “RESET-A” signal pin (34) of 
IC1710 (FPGA).     

 

                      
Do all the fluorescent tubes light up?

NO

Check the individual fluorescent 
tubes for light-up failure.

YES

Replace any defective fluorescent 
tube (s) with new one (s).

YES

Is the power supplied to CN1 and 
CN2 on the inverter unit?   

NO

Check the connection between power 
unit and inverter unit.      

YES

Is the Fuse (F201, F401, F251 or 
F451) fuse in the inverter unit circuit 
functioning?

NO

Replace the blown-out Fuse (F201, 
F401, F251 or F451) fuse on the 
inverter unit. Turn on the power again. 
If the fuse gets blown out again, 
check the short-circuited spot.     

YES

Check T201, T403, T251 and T453 
and their peripheral circuits as 
IC7502B and their peripheral circuits.    

YES

Is the VCC power supplied to the 
control IC (U4) on the inverter unit?   

NO

Check the circuit connected with the 
VCC terminal on the inverter control 
IC (U4).     

YES

Has each control signal come to 
CN1? 
(INV-ON, INV-BRT and PWM-SEL)

NO

Have INV-ON, INV-BRT and PWM-
SEL signal come to SC1702 (PB) in 
the MAIN substrate?    

NO

 Check pins (89) and (19) of IC1710 
(main PWB).

YES

Is the specified control signal input-
ted at IC (U4) (INV-CTL) on the 
inverter unit. 

NO

Check the line between CN1 and IC 
(U4).     

 

YES

Are the Q23, Q25, Q24 and Q26 
transisters at the primary side of 
T201 functioning? 

NO

Check the power line of IC (U4), its 
peripheral circuits or replace IC (U4).     

 

YES

Is the secondary circuit of T201 func-
tioning.

NO

Replace T201 or the T*** transformer 
for the fluorescent tubes, or check 
their peripheral circuits.