Samsung PS42D51SX/XEC, Service Manual

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Troubleshooting
6-4 Samsung Electronics
6-2-3 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 normal but the X, Y Drive Board, Logic Board, or Y Buffer Board is out of order.
- The output voltage of the Main SMPS or the DC-DC SMPS is out of order.
- 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 CN809 of the Main SMPS, CN1, CN2, CN3, CN4 and CN5 of the DC-DC
SMPS, CN of the X Drive Board, and CN of the Y Drive Board, a spark may be generated by the electric charge of the high
capacity capacitor. Therefore, wait some time after separ ating the power cord from the unit.
Are the Vs and Va voltages
normal after removing the CN809
cable from the Main SMPS?
Replace the Main SMPS
Is the output voltage of the
DC-DC SMPS normal when
reconnecting the CN809 cable
and removing the CN1, CN2,
CN4 and CN6 cables from the
DC-DC SMPS?
Replace the DC-DC SMPS
Replace the Y Drive Board
Replace the X Drive Board
Replace the Logic Drive Board
Replace the Y Buffer Drive Board
No
No
Yes
Yes