Samsung UN40KU7000F - BACKLIGHTS

BACKLIGHTS 
Simplied : 40" ~ 55"
Activate Backlights Test1.
Disconnect Lead Cable from Main Board to Power Supply. -
(CN202)
TV Screen for active backlight LEDs. 9
If NO BACKLIGHTS2.
Plus (+) & Minus (-) pin voltages on the Panel Connector. 9
If no pin voltages replace SMPS.•
If voltages exist but no backlight.•
The highest pin voltage (BL Drive Supply). 9
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 • voltage was low and remains low the SMPS is defective.
If the voltage was low and goes high a string of panel LEDs are shorted replace the • Panel.
BACK LIGHT DIMMING PROBLEMS3.
Go to Menu/Picture/Expert/Backlight and vary level (0 - 20). -
If no backlight changes are observed: -
Panel Connector pin voltages and BLU_PWM voltages 9
(CNM801)
while changing backlight level.
If Panel voltages don’t change, and BLU_PWM changes, replace - SMPS.
If BLU_PWM doesn’t change replace - Main Board/T-Con Board.
Simplied : 65"
Activate Backlights Test1.
Disconnect Lead Cable from Main Board to Power Supply. -
(CN202)
TV Screen for active backlight LEDs. 9
If NO BACKLIGHTS2.
Minus (Control) pins & Plus (Supply) pins voltages on the Panel Connector. 9
If no pin voltages replace • SMPS.
If BACKLIGHTS ON BUT PANEL SECTION(S) OFF (for SMPS wired in parallel)3.
The Supply Drive + pins should each measure the same voltages. 9
And the - pins should each measure the same voltages. This veries the SMPS is wired with LED Strings in parallel
and operating correctly.
If a Minus (- ) pin measures low (near 0 volts), a string(s) of LEDs are likely open. -
Replace Panel• .
If a plus pins measures higher than the others, a string of LEDs is also likely opened. -
Replace Panel• .
Can remove Panel connector and verify same open backlight voltage condition. -
Replace Panel• .
If a Plus pin measures low: Remove the Panel connector, if it stays low Replace SMPS. -
If it goes high like the other plus pins, the Replace Panel.
4-5
4. Troubleshooting