Samsung QA65Q90RAK Service Manual page 84

1. If TV Powers On but BACKLIGHTS OFF
Check BLU_ON 0V (when Off) to 3.6Vdc (on) at CN9003B pin 11
9
• If no change replace TV Main Board or OC Box
• If BLU_ON is OK
Check
CNM803A
9
• If missing
Check OCB Cable & One Connect Box:
9
• Perform "One Connect Stand Alone Test" & "Backlight Test"
• If 350 Vdc is OK & BLU_ON is OK
Check BL by removing
9
• If backlights turn on replace defective TV Main Board, if not:
Check with step "SMPS/Panel Operation Test"
9
2. IF Backlights are ON but Panel Section (s) are OFF or not Changing level
Check correct model One Connect Box
9
• If wrong model replace OCB. (can create miss backlight operation)
• If correct model continue "SMPS/Panel Operation test".
3. SMPS/PANEL OPERATION TEST
Check Backlight Supply at each highlighted Capacitor on both LD/SMPS A & B Boards. All should measure the same
9
approx 35Vdc (65" TV)
• If any missing or wrong voltage turn TV power Off and remove panel connectors on the related LD/SMPS
Board. Turn Power back on.
Check 35Vdc Supply.
9
• If still error, replace defective LD/SMPS Board. If OK replace defective Panel. (In Some cases a shorted LED
String can damage the SMPS Supply.)
Use: MUTE 4 1 9
£ £ £
B350Vdc Pins 5 ,
CN9003A BL Control
EXIT to test Panel Backlight
£
6 with B-GND REF Pins ,
1 2
4. Troubleshooting
4-15