50 inch lg plasma issue

[edber]

Hi people

This is my first post here as I am new and I hope you good people can
help with my 50 inch lg plasma problem.So here goes.
When the tv is turned on by the remote first thing in the morning the standby light turns from red to green with an audible click which I think is normal and the picture and sound
come on,but then after a few minutes the screen goes black but the sound
is still there.If the tv is left like this then eventually the screen will come alive
but the picture is all full of plasma squares,but you can just about make out the picture in the background(best way I can describe it),when the picture is like this the tv will not turn off by the remote or the power button on the tv itself.Now here is the puzzling bit,if I unplug the tv at the mains and immediately plug it back in the tv will start up with a perfectly
normal picture and will continue to work perfect for the remainder of the day/night until next morning when all of the above has to be repeated again
i.e turn on with remote,wait a while,then unplug from wall socket,insert back
to wall socket and voila perfect tv again.Can anyone please narrow this
problem down for me.I don't have the exact model number to hand as the tv
is up against the wall.edit-model is 50pc55

[tom66]

Re: 50 inch lg plasma issue

Can we see a picture of the problem?

[edber]

Re: 50 inch lg plasma issue

Hi tom
Thanks for your quick reply.I will have to wait until tomorrow morning to
take a picture of the screen for you as the tv is on now and it wont show the
symptoms until a cold start in the morning.Let me google in the meantime for
a similar picture.

[edber]

Re: 50 inch lg plasma issue

This is not my tv but this is very similar to what happens my screen,this is what I called the
plasma squares.When this is on my tv the tv will not respond to the remote
control or buttons on the tv itself.But if I unplug the tv from the mains and replug back to mains while
the tv is like that picture then the tv will be perfect again with no issues at all.

[tom66]

Re: 50 inch lg plasma issue

This would appear to be a main board fault.

[edber]

Re: 50 inch lg plasma issue

Thanks tom but the tv starts up perfect in the morning and after a few moments the screen
goes black and stays black for another while then that pinky screen comes on
and then the tv wont respond to remote or the tv buttons
and then by unplugging the mains and replugging the tv is perfect again???
Once the tv has been unplugged and replugged after the pinky screen stage,then the tv can be turned on and off
as many times as I like with no issues.
While the tv is in the black screen stage there is a couple of very thin horizontal white lines flickering
at the very top of the screen and the remote works with this black screen.
Remote will only not work when the tv is in the pinky screen stage.

[tom66]

Re: 50 inch lg plasma issue

The lack of ability to control the TV with a moving image tells me it is most likely a main board fault. There's a small chance the PSU is faulty -- bad capacitors may cause this -- but the symptoms don't quite match.

[edber]

Re: 50 inch lg plasma issue

It seems as if something needs a bit of time to get fully powered up and it
gets its extra power when the tv gets unplugged and replugged,kinda
like a power surge.
Its a puzzling one.Can a bad capacitor be slow to get full current/voltage but once it has full voltage/current it keeps the voltage/current to run the tv normal?
The tv can be controlled with the remote when the picture has returned to normal only after unplugging and replugging.
The tv will also respond to the remote in the black screen stage,only in the pinky screen stage the tv will not respond to commands from remote or tv buttons.

[tom66]

Re: 50 inch lg plasma issue

Sort of. A bad capacitor is often very temperature sensitive, and starts working properly when warmed up, sometimes.

[edber]

Re: 50 inch lg plasma issue

Now,i haven't done any heatsink test or looked for bulging caps as I don't like
touching something that has potential high voltages.Im too bloody carefull
when it comes to high voltages .But I suppose I should look for bulging caps
and see if there is any bulging.Im just hoping with the help of this forum that my issue
can be narrowed down so that I can remove the offending board with the bad component
and bring it to a repair shop and tell the guy the exact component that needs replacing.

[hienton2]

Re: 50 inch lg plasma issue

Hot air the main board or psu before you start in the moning. See how it is.

[edber]

Re: 50 inch lg plasma issue

Hot air the main board or psu before you start in the moning. See how it is.

Cheers for the input but getting a hairdryer behind the tv will be difficult.
I see your logic but I fail to see how that would help with fault finding as these components
are meant to be cooled by the fan at the top,which is working by the way.

[tom66]

Re: 50 inch lg plasma issue

The logic is the components are failed and have become temperature sensitive.
You are applying heat to certain parts in an attempt to locate the temperature sensitive part.
Otherwise, you cannot know what part is failed.

[edber]

Re: 50 inch lg plasma issue

The logic is the components are failed and have become temperature sensitive.
You are applying heat to certain parts in an attempt to locate the temperature sensitive part.
Otherwise, you cannot know what part is failed.

I understood the logic but is there any specific component that I would need
to aim the heat at?What components are heat sensitive?May narrow things
down a bit for me.Even if I knew which board has the faulty component then
I could look into replacing that board.

[tom66]

Re: 50 inch lg plasma issue

The idea is to apply heat to a large, general area, say, maybe the power board or main board, then see if the symptoms improve. If they do, then you need to narrow it down further to specific regions of each board.

[edber]

Re: 50 inch lg plasma issue

The idea is to apply heat to a large, general area, say, maybe the power board or main board, then see if the symptoms improve. If they do, then you need to narrow it down further to specific regions of each board.

Ok tom I see what you are saying.Trouble is I would be confined for space as to where to leave the tv while it is off the wall,small apartment and all that.
Its just maybe with the descriptions I gave as to how the tv is behaving I
thought that might narrow it down or at least pinpoint to a certain board.

[hienton2]

Re: 50 inch lg plasma issue

May be the micro on main board or source vcc for this ic.

[tom66]

Re: 50 inch lg plasma issue

I do think it is a main board or power board issue, that's narrowed it down pretty considerably IMO.

[edber]

Re: 50 inch lg plasma issue

May be the micro on main board or source vcc for this ic.

Hi hienton,any picture of this micro?So id know what to look for.

[edber]

Re: 50 inch lg plasma issue

I do think it is a main board or power board issue, that's narrowed it down pretty considerably IMO.

So I go and buy a main board and power board.Will look at prices so.