BACKLIGHTS
Simplified : 40" ~ 55"
Activate Backlights Test
1.
Disconnect Lead Cable from Main Board to Power Supply.
-
(CN202)
TV Screen for active backlight LEDs.
9
If NO BACKLIGHTS
2.
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 PROBLEMS
3.
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
(CNM803)
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
.
Simplified : 65"
Activate Backlights Test
1.
Disconnect Lead Cable from Main Board to Power Supply.
-
(CN202)
TV Screen for active backlight LEDs.
9
If NO BACKLIGHTS
2.
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 verifies 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
