Samsung UN40KU630DF Service Manual page 105

BACKLIGHTS
„
1. Activate Backlights Test
Disconnect Lead Cable from Main Board to Power Supply. (CN202)
-
√ TV Screen for active backlight LEDs.
2. If NO BACKLIGHTS
√ Plus (+) & Minus (-) pin voltages on the Panel Connector.
If no pin voltages replace SMPS.
-
If voltages exist but no backlight:
-
√ The highest pin voltage (BL Drive Supply )
Remove Panel connector and measure again to compare.
-
If the voltage was high and stays the same high reading a string of Panel LEDs are open. Replace the Panel.
-
If the v oltage was low and remains low the
-
If the voltage was low and goes high a string of panel LEDs are shorted replace the
-
For BACKLIGHT DIMMING PROBLEMS:
Menu → Picture → Backlight and vary level (0 – 20)
• Go to
• If no backlight changes observed:
√ Panel Connector pin voltages and BLU_PWM voltages (CNM801) while changing backlight level.
• If Panel voltages don't change, and BLU_PWM changes, replace
• If BLU_PWM doesn't change replace
:
SMPS
Main/T-Con Board.
is defective.
SMPS.
4. Troubleshooting
Panel.
4-5