3. Component doesn't display

Check J5004

Can you see the normal waveform?

Yes

Check the input of Component switch(IC5001). Can you see the normal waveform?

Yes

Check the output of Component switch(IC5001). Can you see the normal waveform?

Yes

Check the input of MST3361(IC7012, Pin 6,9,12). Can you see the normal waveform?

Yes

No

No

No

No

J5004 may have problem. Replace this Jack.

After checking the input TR of component, you should decide to replace component switch or not.

After checking the Power of component switch you should decide to replace component switch or not.

After checking the Power of MST3382M you should

decide to replace MST3382M or not.

Check the output of MST3361(IC7012 ). Can you see the normal waveform?

Yes

Check the input and output of BCM3550(IC1001). Especially you should check

The H,V sync and clock.

Can you see the normal waveform?

No

Yes

After checking the Power of MST3361 you should decide to replace MST3361 or not.

This board has big problem because Main chip(BCM3550) have some troubles. After checking thoroughly all path once again, You should decide to replace BCM3550 or not.

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LG Electronics 20LS7D(C)-UB service manual Component doesnt display