LL-171G. Complete - Sharp Monitor Service Manual (repair manual). Page 25

LL-171A-W/B/LL-171G-W/B

TROUBLESHOOTING

5 – 1

■

 NO POWER SUPPLY

* Inverter cable  is separated?
* Inverter cable is disconnection?
* Check the output of each pin
  2 pin (ON/OFF) 4pin (DIM)

No power supply

Does LED turns on in green 
when power switch is turned 
on?

No

No

No

No

No

Yes

Yes

Yes

Yes

Yes

No output +5V, 12V from

power supply unit.

Yes

Replace power supply unit.

1) PC is turned off?
2) RGB cable is disconnected?
3) Synchronizing signal is output from RGB 

cable?

Check whether the unit is in power save 
mode (synchronizing signal is not input.).

Synchronizing signal is input to main PWB?

Replace RGB cable 
with a new one.

LED turns on in orange?

Check power input system.

Replace any defective unit.
[ 1) Power supply PWB, 2) Main PWB,  
3) Switch PWB, 4) Audio PWB] with a new one.

Backlight turns ON?

Check for RGB cable input 
signal.

Replace RGB cable.

Normal

Normal

Normal

Defective

Defective

*  Check inverter PWB unit.
Note: Use caution when checking output 

side because it has a high voltage. 

Replace LCD module lamp with 
a new one.

Replace inverter PWB 
unit with a new one.

A

1) Power  Inverter supply PWB Normal?
    Connected with the MAIN PWB properly?
2) Blown out fuse (D201)?
    Check VCC5V+, VCC2.5V and VCC3.3V
    are output?
3) Check POWER switch and LED for 
     breakage.
4) Check the Audio PWB of 12V connected
     too hastily.