[Catmadcaz]

I own a JVC InteriArt television (CRT type television) and the picture seems to have moved down the screen leaving a black bar across the top,the picture seems a little fuzzy with flickering faint horizontal lines across the screen.

I recently had a stereo speaker on top of the television and was wondering if this could be the cause of my problems and if so how do I correct it.

Thanks for any help you can offer.

[niall campbell]

speakers have to be 1 metre away unless they are shielded ( tin foil round magnet

or you kill the telly

[John Currie]

You need to report back with the model no (taken from the rear label)...not the model name.

[LCDMAN]

Quote:

Originally Posted by niall campbell

speakers have to be 1 metre away unless they are shielded ( tin foil round magnet or you kill the telly

You might as well put tissue paper round it! Tin foil (aluminium foil) has no effect at all on magnetic flux, you need mu-metal. Either way, more recent CRT shadow masks are made of non-ferrous materials so they don't suffer from the same magnetic effects as they used to in the "bad old days". It wouldn't have such a linear effect, but would radiate from where he had the speaker.

If he had magnetized ("gaussed up") his shadow mask then he wouldn't have those symptoms, he would have wonderful psychedelic colours as the electron beam was attracted into the mask rather than passing through it.

[Catmadcaz]

The number from the label at the back is AV 28WFT 1EKS.

[LCDMAN]

Quote:

Originally Posted by Catmadcaz

I own a JVC InteriArt television (CRT type television) and the picture seems to have moved down the screen leaving a black bar across the top,the picture seems a little fuzzy with flickering faint horizontal lines across the screen.

I recently had a stereo speaker on top of the television and was wondering if this could be the cause of my problems and if so how do I correct it.

Thanks for any help you can offer.

Look on the rear, any adjustment for vertical position? Is the image moved down the screen with the bottom missing or is it "squeezed" in height?

[Catmadcaz]

No there is nothing on the rear and yes the screen goes down and I can't see the bottom of the picture.I turned it off earlier for 20 mins and when I turned it back on the screen went a faint lilac colour with splotches of green,blue and red across the screen and like a rainbow across the bottom.

[John Currie]

Quote:

Originally Posted by Catmadcaz

No there is nothing on the rear and yes the screen goes down and I can't see the bottom of the picture.I turned it off earlier for 20 mins and when I turned it back on the screen went a faint lilac colour with splotches of green,blue and red across the screen and like a rainbow across the bottom.

There are no controls at all on the rear of modern TVs...there hasn't been any for at least 20yrs.
This fault has nothing whatsoever to do with you putting anything on top of the set.
What started off as probably a dry joint on the "Frame Output" IC may now be permanent...do not switch it on or run it in this condition...you need to get it examined by a TV repairman...it is not D-I-Y fixable.

[Catmadcaz]

I have got another tv so I will swap it over and use that instead until I get it fixed,thank you very much for all your help.

[LCDMAN]

Quote:

Originally Posted by Catmadcaz

No there is nothing on the rear and yes the screen goes down and I can't see the bottom of the picture.I turned it off earlier for 20 mins and when I turned it back on the screen went a faint lilac colour with splotches of green,blue and red across the screen and like a rainbow across the bottom.

The rainbow effect is the clue here. You've managed to magnetize part of the tube called the shadow mask. It is like a large metal t-bag - full of holes - that the electron beam passes through before hitting the phosphors on the back of the screen. It is shown as "F" on this image;

http://electronics.howstuffworks.com/tv4.htm

In a bit more detail in this image;

http://electronics.howstuffworks.com/tv10.htm

If the shadowmask has any magnetism then it can divert the beams, so that they don't pass through it in the right place, or hit it and don't pass through at all. Hence the crazy rainbow colours you see. They are usually made of materials which have a low ferrous content, to avoid induced magnetism.

The shadow mask can be slightly magnetised by the earths magnetic field in everyday use, so a coil of wire is wrapped around it (inside) and receives a pulse every time you turn the unit on - this is the "de-gauss coil", it de-magnetises ("de-gausses") the shadow mask. You often hear this as a large vibration or "whump" sound when you turn the TV on (especially large screen CRTs). The same rainbow effect can happen if you move/turn around the CRT too much when it is switched on.

This can be de-magnetised quite easily using what is known as a "de-gauss" wand (a hand held coil). A 5 minute job for any decent TV engineer - can be done (is better done) in-situ, no need to take your TV away.

[LCDMAN]

Quote:

Originally Posted by John Currie

There are no controls at all on the rear of modern TVs...there hasn't been any for at least 20yrs.
This fault has nothing whatsoever to do with you putting anything on top of the set.
What started off as probably a dry joint on the "Frame Output" IC may now be permanent...do not switch it on or run it in this condition...you need to get it examined by a TV repairman...it is not D-I-Y fixable.

Beg to differ John, but seems like classic gaussed up tube or metalwork mate. Rainbow colours, image shift, what image is there is fuzzy - all typical symptoms of a magnetised shadow mask. He does say he sat a speaker on there - we don't know how big, but obviously big enough. He sat it on top and now the image has moved down the screen - seems pretty clear cut to me. Either that or he has magnetised part of the metal frame holding the CRT or the CRT band and it is having a residual effect - a de-gauss will sort that too.

If the frame IC had a dry joint or had gone then I don't think he would get anything like the image he does - he'd be lucky to get a spot! Frame IC can't control the colours.

[John Currie]

Quote:

Originally Posted by LCDMAN

Beg to differ John, but seems like classic gaussed up tube or metalwork mate. Rainbow colours, image shift

No problem, we're all entitled to our opinion and as we can't examine the set it's guesswork at our end.
These can also be symptoms of a missing +ve or -ve supply to the TDA8350 Frame/E/W IC in this model...it does exhibit a rainbow effect on the screen with this fault.