I bought an LG 55-inch about half a year ago, and recently I noticed that when I turn it on at medium volume, there's a quiet squealing sound coming from the case. The speaker isn't damaged, the picture looks fine. Is it a capacitor? Do I need to take it to a service center or can I try to fix something myself?
A high-pitched noise coming from inside your TV is usually capacitors or inductors in the power supply acting up! When they age or work at their limit, they start making a sound at a certain frequency. The picture can be perfectly fine in the meantime, because the electronics are still holding up - the noise is just a side effect. Sometimes this sound shows up specifically at medium volume, because that's when there's a certain level of stress on the power supply.
There's nothing you can do about it yourself! This isn't something you can just add oil to or tighten a bolt and call it good. Better not risk it and take it to a service center - especially since your TV is relatively new and probably still under warranty! Check your purchase documents. If the warranty's still valid, they should handle the replacement or repair for free.
While you're waiting to get it fixed, you can try just watching at a different volume - maybe the noise will stop being so annoying. But you should really still take it to a service center, because this kind of problem usually doesn't fix itself and can get worse over time!
Basically, the previous answer about capacitors is right, but here's the thing - the beeping might depend on the volume precisely because the power supply is getting more load. When the sound is louder, the amplifier draws more power, and if there's a faulty component in the PSU, it starts beeping more intensely. It's not dangerous for the TV in terms of explosions or short circuits, but it sounds awful.
Capacitors typically don't fail within six months under normal operation, so it's most likely a manufacturing defect or factory flaw. I wouldn't recommend opening the TV yourself - there's high voltage in the power supply, and if you do find something, you could desolder it wrong and end up with serious problems. Especially since the warranty should still be valid if you bought it half a year ago.
Call LG service and describe the problem - they'll most likely replace the PSU under warranty for free, or swap out the whole TV if they have one in stock. They usually don't make a fuss about this kind of thing when the device is new.
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