Samsung HPR4272CX/XAC Service Manual page 43

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 Video Board is normal but the X, Y Drive Board, Logic Board, or Y Buffer Boards are 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 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.
6-4
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 Drive Board
Replace the X Drive Board
Replace the Logic Drive Board
Replace the Y Buffer Drive Board
Replace the Main SMPS
Replace the DC-DC SMPS
Samsung Electronics