LG OLED TV won't turn on

In short

If your LG OLED TV won't turn on, starts unreliably, the standby LED stays dark, or you hear a soft click from inside, the cause is often not the panel — it is the power supply (power supply board).

Many LG OLED power supply boards use film capacitors rated 820 nF (nanofarads; equal to 0.82 µF / microfarads). Over years they lose capacitance. Supply becomes unstable: boot failures, intermittent behaviour, aborted maintenance cycles.

Typical failure pattern

The pattern is often intermittent: sometimes the set starts, sometimes it is dead. After unplugging and plugging back in it may work briefly — then fail again. Pixel refresh (Pixel Refresher) aborts or never starts because the supply collapses during standby.

Common observations in practice:

• No response to remote or power button
• Standby LED stays dark or flashes briefly
• Short click / relay-like sound with no picture
• Brief recovery after unplugging, then relapse
• Pixel refresh or other standby jobs abort

Root cause: aging film capacitors (often 824J 500V)

Aged film capacitors, measured after removal: 17.32 nF and 89.5 nF. The nominal value is 820 nF.

Affected power supply boards frequently carry yellow film capacitors, often from Carli. The marking 824J 500V means: 824 = 820 nF (0.82 µF), J = tolerance class, 500V = rated voltage. These are filter and stability parts in the switch-mode supply — not cosmetic extras.

Aging causes capacitance loss: measured values often sit in the 7xx nF range, sometimes far lower — well under 100 nF. With so little left, the supply becomes noisy. Result: unreliable start or collapse under load / in standby.

Wide impact across the LG OLED line

This wear pattern essentially hits the power supplies of the LG OLED range where these film capacitors were fitted — practically the whole OLED landscape that shares the same power supply board families. Well-known series such as C8 / C9 / CX / C1 and related chassis show up regularly in workshop practice.

Not every single set is faulty. But the component risk runs through the OLED power supply board landscape: wherever 820 nF film caps of this type sit, capacity loss over time is a realistic scenario — not a one-off mystery.

Why film caps in the power supply board matter so much

Switch-mode supplies need stable filtering and clean voltage conditions so control rails, standby rails and the main supply can rise cleanly. When film caps lose capacitance, power supply board stability drops: ripple rises, protection trips, soft-start fails.

That is why the symptom often looks like “the TV is dead” — even when panel and mainboard may still be fine. Diagnosis starts at the power supply board, not the expensive screen.

Safety notice

Mains voltage is lethal. Working on an open set and on the power supply board means dangerous voltages. Electrolytic capacitors can hold high residual charge after unplugging — discharge before you measure or desolder. Never measure under power or swap parts while the TV is connected to the mains. Up to about 400 V can remain on the large electrolytic capacitors even after switching off. After disconnecting from the mains, wait at least 2 hours and still measure, with a multimeter with a range of at least 600 V. Only continue once the voltage is ideally below 30 V.

If you are unsure: unplug, do not open, and leave diagnosis to a workshop. AmparioWeb offers tested replacement power supply boards and fixed-price repair — see Repair.

Diagnostic pointers (high-level)

Power supply board EAY65689423 (65 inch), removed. Block 1 at the front with ICL, fuse F100 and 4-MOSFET block, block 2 at the back with fuse F801 and 2-MOSFET block. Practically always one of the two blocks is broken.

Goal is rough triage — not a step-by-step guide to live work. After safe unplugging and wait / discharge of electrolytics, useful checks include:

• Whether standby / auxiliary rails on the power supply board appear at all (only by qualified methods, de-energised where required)
• Visual check of fuses and burn / overvoltage marks
• Electrolytics for bulging, leakage or discoloration
• Always desolder film caps (e.g. 824J 500V) to measure them: in-circuit you also measure the surrounding circuit
• Target value is 820 nF. Aged film caps often sit far below (measured e.g. 17.32 nF and 89.5 nF). They are a wear part and should be replaced in every repair

DIY repair vs professional replacement

Replacing the film capacitors is technically correct: they are a wear part, always aged on these power supply boards, and should be replaced in every repair, even if the actual fault lies elsewhere. That only works with proper parts, clean soldering and power supply board know-how. Used boards from the second-hand market are a gamble: they often still carry the same aged Carli film caps, and the fault returns.

AmparioWeb’s stance is clear: prefer a tested replacement power supply board or fixed-price repair over roulette with unknown old boards. Find parts and numbers via Find parts and Replacement power supply boards.

What AmparioWeb offers

You do not need a panel-replacement scare when the power supply board is the cause. AmparioWeb helps identify the right power supply board, supplies tested replacements, and repair paths for LG OLED no-power issues.

Next step: check model / power supply board number and request Repair — or search Replacement power supply boards.