Help Needed with LG TV Power Board Repair (Model No: OLED 55EG9A7V, Board No: LGP55B7-170P)

[justice171]

Hi everyone,

I'm currently troubleshooting an issue with my LG TV (Model No: OLED 55EG9A7V, Power Board No: LGP55B7-170P) and would appreciate your guidance.

When I press the power button, the standby LED flickers three times, and the relay clicks multiple times before stopping. During this time, I measured the voltages:

• Over P201: I receive all the correct voltages.
• Over P202: I only receive 12V, but the 24V is missing.

The 24V is used to power the display board (Tcon) via the flex cable, but even when I disconnect the flex cable, the 24V is still not present.

I'm unsure how to further diagnose the missing 24V. Could someone help me identify where the problem might be or provide any tips on how to proceed?

Thanks in advance for your assistance!

Best regards,

[CapLeaker]

There can only be like a handful things.
secondary on the transformer open, shorted 24V high speed diode on the secondary, PFC not working (if the PFC isn’t boosting the voltage on the main filter capacitor) there is usually no 24V either, bad solder joints, a wire from the transformer came off one leg… that’s all I got for ammo this morning. Lol
after all the 12V is coming from the same transformer, load the secondary with some light bulbs and see if it handles any current or not.

[Diah]

no EVDD 24V because MICOM shut it down as T-CON send SOS via lower LVDS to mainboards.
disconnect the lower LVDS between T-COn and Mainboards... turn on take look on the audio optic ports if it lit red and remain on... screen will remain black

[justice171]

There can only be like a handful things.
secondary on the transformer open, shorted 24V high speed diode on the secondary, PFC not working (if the PFC isn’t boosting the voltage on the main filter capacitor) there is usually no 24V either, bad solder joints, a wire from the transformer came off one leg… that’s all I got for ammo this morning. Lol
after all the 12V is coming from the same transformer, load the secondary with some light bulbs and see if it handles any current or not.

I will check it out thank you.

[justice171]

no EVDD 24V because MICOM shut it down as T-CON send SOS via lower LVDS to mainboards.
disconnect the lower LVDS between T-COn and Mainboards... turn on take look on the audio optic ports if it lit red and remain on... screen will remain black

I will verify thanks