Phillips LCD - Static on A/V source

[caphair]

Hello I was wondering if there was a way to clear up the static picture when using a/v input on this tv. It's confirmed that it's the tv itself as testing on others results in a clear picture.

I've tried cleaning the terminals with fine sandpaper but there's no difference at all. Would it be a circuit issue?

[R_J]

Re: Phillips LCD - Static on A/V source

That looks like a bad cap on one of the regulator ic's, likely on the main board. It their output cap. goes bad, as in open, the ic can oscillate causing this type of interferfnce.

[caphair]

Re: Phillips LCD - Static on A/V source

That looks like a bad cap on one of the regulator ic's, likely on the main board. It their output cap. goes bad, as in open, the ic can oscillate causing this type of interferfnce.

I only see one cap part of the av board. Bottom right. Would it be that?

[R_J]

Re: Phillips LCD - Static on A/V source

There are a couple caps on the board, top right (Digital Main), I would suspect C3608, the one next to the black coil . I see there are no screws in the power supply/inverter board, was the interference there before the screws were removed?
I take it this is the same tv from this thread https://www.badcaps.net/forum/showth...t=67328&page=2

[caphair]

Re: Phillips LCD - Static on A/V source

Yes same TV

[caphair]

Re: Phillips LCD - Static on A/V source

So it would be the caps on the main board not the RF board or main PSU board?

[R_J]

Re: Phillips LCD - Static on A/V source

Is the problem only there when on tuner (R.F.)?

[caphair]

Re: Phillips LCD - Static on A/V source

Is the problem only there when on tuner (R.F.)?

Hdmi is perfect as well as coaxial input. Only there with A/V. Haven't tried component source

[R_J]

Re: Phillips LCD - Static on A/V source

By A/V I will assume composite input or S-Video, So if hdni is ok, then the fault is not likely on the digital board (top right board). I would start by checking if you are missing a ground between the a/v board and the main/power supply board
If the problem is with the VIDEO input, check the trace for in the signal path, maybe there is a poor connection on one of the ribbon cables between the boards
If there is a poor ground for the video board, you will be picking up noise from the ccfl high voltage circuit which will interfere with the video signal.

[caphair]

Re: Phillips LCD - Static on A/V source

Visually checking all connections to the a/v board. Solder joints all look good too. I tried removing the ribbon cable and cleaning the contacts but that didn’t do anything.

[R_J]

Re: Phillips LCD - Static on A/V source

Try the component input, You can switch the TV input to component and just plug the source video into the green input, that should give a green only picture. and see if the interference is still there.

[caphair]

Re: Phillips LCD - Static on A/V source

Try the component input, You can switch the TV input to component and just plug the source video into the green input, that should give a green only picture. and see if the interference is still there.

Actually tried that before and get no picture at all. Not sure if it's the source I'm using or not

[R_J]

Re: Phillips LCD - Static on A/V source

Use the same source that is giving you the picture on the video input.
Have you tried the VGA input?

[caphair]

Re: Phillips LCD - Static on A/V source

Use the same source that is giving you the picture on the video input.
Have you tried the VGA input?

Yes it's the same source I'm using. No haven't tried VGA input. Do all these inputs use their own voltages or are they shared?

[R_J]

Re: Phillips LCD - Static on A/V source

All inputs are switched and processed by ic3301.

[caphair]

Re: Phillips LCD - Static on A/V source

I noticed this tv’s mains plug doesn’t have a ground plug. Would that cause noise? Though I doubt it would be designed without a ground plug without filtering noise through the inputs

[R_J]

Re: Phillips LCD - Static on A/V source

Most tv's these days don't have a mains ground, That is not your problem, if it was, don't you think it would also effect the hdmi and rf input also.
Have you tried installing the power supply/inverter screws to see if that has any effect on the interference?
Any filtering in the a/c input circuit is to prevent noise coming OUT of the tv's switching power supply.

[caphair]

Re: Phillips LCD - Static on A/V source

Ah ok. Yes having all screws on and tight causes no difference. I’m about to just order an ab to hdmi converter for $10 and call it done I think

[R_J]

Re: Phillips LCD - Static on A/V source

Don't you have the service manual for this tv? It sure looks like the video ground is not making contact, If you pull out the video plug so the rca ground is not connecting does it change the interference? I can't see why you can't get a video signal on the component input. that would also check a different input that comes from the a/v board

[caphair]

Re: Phillips LCD - Static on A/V source

Don't you have the service manual for this tv? It sure looks like the video ground is not making contact, If you pull out the video plug so the rca ground is not connecting does it change the interference? I can't see why you can't get a video signal on the component input. that would also check a different input that comes from the a/v board

If I pull out the video plug where the ground isn't connected the interference does change but still not clear. No video signal when I try on component input. Do you think it's related?