Samsung PL-42Q91HDP, Service Manual

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Troubleshooting
4-4 Samsung Electronics
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No Picture (When audio is normal)
Symptom - Audio is normal but no picture is displayed on the screen.
Major Checklist
- This may happen when the Main Board is functioning but the X, Y Main Board, Logic Board, or Y Buffer
Boards are not.
- The output voltage of the Main SMPS.
- This may happen when the LVDS cable connecting the Main Board and the Logic Board is disconnected.
Troubleshooting
Procedures
Caution
When separating and connecting the cables such as CN810, CN809, CN808, CN807 of the Main SMPS, CN4701
of the X Main Board, and CN5707 of the Y Main Board, a spark may be generated by the electric charge of the
high capacity capacitor. Therefore, wait some time after disconnecting the power cord from the unit.
CN810
CN809
CN808
CN807
Are the Vs and Va voltages normal after
removing all cables from the SMPS?
(CN810, CN809, CN808, CN807)
Replace the SMPS
Yes
No
Did problem improve?
Did problem improve?
Did problem improve?
Did problem improve?
Replace the Y Main Board
Replace the X Main Board
Replace the Logic Board
Replace the Y Scan Board
No
No
No
No
Yes
Yes
Yes