Samsung UN55KS850DF, Service Manual

Page: 54 / 105

BACKLIGHTS
„
Activate Backlights Test 1. :
Disconnect Lead Cable from Main Board to Power Supply.
-
TV Screen for active backlight LEDs. √
If NO BACKLIGHTS 2.
Minus (Control) & Plus pins (Supply) on the Panel Connector voltages to the Panel. √
If no pin voltages replace SMPS.
-
If BACKLIGHTS ON BUT PANEL SECTION(S) OFF 3.
The Supply Drive √ + pins. All should measure same.
If a
-
+
pin measures higher voltage, a string(s) of LEDs are likely open.
Remove Panel connector and verify same open backlight voltage condition.
-
Replace Panel .
If a 4. + pin measures low voltage disconnect connector to panel
The Low Plus Pin Voltage again. √
If it stays low the
-
SMPS is defective, if it goes high, defective Panel .
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 • SMPS .
If P-DIM doesn’t change replace • Main/T-CON Board .
MUTE 4 1 9 EXIT to test Panel Backlight Sections.
4-6
4. Troubleshooting