Backlights; For Backlight Dimming Problems - Samsung UN55KS9000F Service Manual

4. Troubleshooting

BACKLIGHTS

„
1. Activate Backlights Test
Disconnect Lead Cable from Main Board to Power Supply.
-
√ TV Screen for active backlight LEDs.
2. If NO BACKLIGHTS
√ Minus (Control) & Plus pins (Supply) on the Panel Connector voltages to the Panel.
If no pin voltages replace SMPS.
-
3. If BACKLIGHTS ON BUT PANEL SECTION(S) OFF
√ The Supply Drive
+
If a pin measures higher voltage, a string(s) of LEDs are likely open.
-
Remove Panel connector and verify same open backlight voltage condition.
-
4. If a + pin measures low voltage disconnect connector to panel
√ The Low Plus Pin Voltage again.
If it stays low the
-

For BACKLIGHT DIMMING PROBLEMS:

• Go to Menu £ Picture £ Backlight and vary level (0 – 20)
• If no backlight changes observed:
√ Panel Connector minus (-) pin voltages and P-DIM voltages (CNL801) while changing backlight level.
• If minus Panel voltages don't change, and P-DIM changes, replace
• If P-DIM doesn't change replace
MUTE 4 1
4-6
:
+ pins. All should measure same.
SMPS is defective, if it goes high, defective Panel.
Main/T-CON Board.
9 EXIT
to test Panel Backlight Sections.
Replace Panel.
SMPS.