42LY99-ZC (CHASSIS:LD75C) - LG TV Service Manual (repair manual). Page 15

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1) After lighting up once, it does not discharge minutely from module. 
2) The relay falls.(There is an audible “click”.)
3) The color of the front LED turns from green to red.

Is the Power

Board normal?

Replace the Power Board.

Is the output the normality Low/High
voltage except Stand-by 5V?

Yes

No

No

Is the

each connector

normal?

Replace the connector.

After connecting each connector do
they operate normally? 

Yes

No

No

Is the VSC Board

normal?

If it operates normally after
removing the P900, P901
: Replace VSC Board

Is the output voltage normal after
removing P900, P901 of VSC Board?

No

Yes

1) No OSD and image occur at screen.
2) It maintains the condition where the front LED is green

Does

minute discharge 

at Module?

Is output the normality

Low/High voltage except

stand-by 5V?

Is the inverter on?

Check the LCD Module.

Yes

No

Yes

Replace the Power

board.

No

No

Is the LVDS 

cable normal?

Reconnect the LVDS cable in P800.

Yes

No

Is the IC700

(FLI8548) Output

normal?

Replace the VSC.

No