In short
LG OLED mainboard or power supply means: which board to suspect first — mainboard or power supply board?
Symptoms drive the order. Buying both blind is expensive. AmparioWeb maps via model/board number and fixed-price repair.
Symptom → suspicion
Opened LG OLED CX, face down: power supply board on the left, green mainboard on the right, in the middle the black cover plate over the T-Con board. The power supply board powers all boards, the mainboard handles picture, sound and connections.
Rough heuristic (no substitute for measurement). Exceptions are possible; if in doubt, call in a TV technician:
- Dead / standby LED off → power supply board first
- Blink code / click no picture → can be the power supply board, but does not have to be (mainboard or panel also possible)
- Only starts after several attempts → mostly power supply board
- House fuse trips when plugging in or switching on → always power supply board
- Switches off by itself after a while, standby LED stays red, every power-on attempt clicks, TV does not start → in our experience mainboard (especially prone: LG CX series)
- Picture OK, apps/HDMI broken → mainboard/software
- Lines while powered → panel path, not blind power supply board swap
Related
stays black, standby LED off, red LED, power supply board swap.
Document
Model, board print (often EAY… / EAX…), blink, click, HDMI influence.
Safety
Mains is lethal. Live diagnosis only for pros. The large electrolytic capacitors can hold up to about 400 V even after switching off: wait at least 2 hours, measure with a range of at least 600 V and only continue once the voltage is ideally below 30 V.
AmparioWeb
Tested power supply boards and mainboards; fixed-price repair of power supply boards. We do not offer mainboard repairs.
Frequently asked questions
- Always power supply board first?
- For dead/no standby: often. For HDMI/apps-only: mainboard/software.
- Both dead?
- Possible after surge — still order, not double-buy.
- Panel?
- Lines/burn-in/edge dead pixels → panel path.
- DIY?
- Exact number + safety — power supply board swap.
- Help?
- Find number then repair.
Not sure which part is affected? Use our symptom finder to narrow down the cause.
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Power boards for LG OLED — tested under load, 12-month warranty.
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