Samsung PS42C7HX/XEC - Page 73

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 Main 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 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.
Are the Vs and Va voltages
normal after removing the
CN809 cable from the
Main SMPS?
Is the output voltage of the
DC-DC SMPS normal when
reconnecting the CN809 cable
and removing the CN2, CN4
and CN5 cables from the
DC-DC SMPS?
Replace the Y Main Board
Replace the X Main Board
Replace the Logic Main Board
Replace the Y SCAN Board
Replace the Main SMPS
Replace the DC-DC SMPS