Samsung Plasma TV, humming buzzing sound

[michael4wave]

Hi there.
got problem with sound.
TV worked fine all the time, and within a month the buzzing started.
at the beginning it was barely audible, now its unbearable.

basically I hear humming buzzing very annoying
the buzz vary depends if tv displays light or dark colours.
Although changing brightness (any tv settings) doesnt affect it.

I tried to narrow down a problem by isolating components.
I unplugged all sus boards leaving power_supply, av and main cpu board.
and still hear same sound.
I replaced power supply board => problem still the same.

I'm planning to replace AV board.
Do you recon it could help?

What could cause it ?


tv spec:
Plasma Samsung PS-50C96HD
POWER SUPPLY PCB = BN44-00189A
AV PCB = BN94-01177C
DIGITAL PROCESSING PCB = LJ41-04776A

[tom66]

Re: Samsung Plasma TV, humming buzzing sound

Would it be possible for you to make a recording of the noise and upload it, it sounds like it could be a 50Hz "ground loop" effect caused by a loose ground connection somewhere.

[michael4wave]

Re: Samsung Plasma TV, humming buzzing sound

Would it be possible for you to make a recording of the noise and upload it, it sounds like it could be a 50Hz "ground loop" effect caused by a loose ground connection somewhere.

Hi Tom66
yes you right, I checked on youtube what 50hz ground loop sounds like
and yes.. that's the noice.

I just wonder how that developed over time, and how to fix it?

some says.. disconnect ground on one side.
like remove ground from tv chassin.

any thoughts ?

[tom66]

Re: Samsung Plasma TV, humming buzzing sound

The most likely cause is one of your devices attached to your TV is not properly grounded and passing ground return current through the ground.

Try disconnecting devices one at a time, and see if the issue is resolved.

Whatever you do, DO NOT disconnect any device grounds currently connected, as this removes a vital safety system that must be preserved.

[michael4wave]

Re: Samsung Plasma TV, humming buzzing sound

here is what I found out.
I have another small samsung tv. (tested, same result)
the only thing connected at the moment is PS3 using RCA cable.
on both tv I got humm, buzz.. so it must be ground loop buzz.

tried another rca cable.. same buzz.
either I have both cable fautly or there is something else.

found one solution on ebay called "RCA GROUND LOOP ISOLATOR".
I might give it a try.

now I know what cause ground loop in general.

but I dont understand why that issue developed over time.
I didnt have that problem in past.

any thoughts ?

[tom66]

Re: Samsung Plasma TV, humming buzzing sound

Can be due to a rusty ground connection.