No Picture (When Audio Is Normal) - Samsung PS42E7SX Service Manual

Troubleshooting

6-2-3 No Picture (When audio is normal)

Symptom - Audio is normal but no picture is displayed on the screen.
- This may happen when the Main Board is normal but the X, Y Main Board, Logic Board, or Y Buffer Board is out of order.
Major Checklist - 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
When separating and connecting the cables such as CN809 of the Main SMPS, CN1, CN2, CN3, CN4 and CN5 of the DC-DC
Caution SMPS, CN of the X Main Board, and CN of the Y Main 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.
6-4
Are the Vs and Va voltages
No
normal after removing the CN809
cable from the Main SMPS?
Yes
Is the output voltage of the
DC-DC SMPS normal when
No
reconnecting the CN809 cable
and removing the CN1, CN2,
CN4 and CN6 cables from the
DC-DC SMPS?
Yes
Replace the Y Main Board
Replace the X Main Board
Replace the Logic Board
Replace the Y Scan Board
Replace the Main SMPS
Replace the DC-DC SMPS
Samsung Electronics