5 replies to this topic

[Official Ninja]

I have this nice 1987 Hitachi TV that works great except the bottom left corner of the screen looks like there is a magnet messing up the color. Could it be the TVs own speaker causing this?? Anyone know of anything I can do about it?

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[Official Ninja]

Official Ninja, on Mon Aug 15, 2011 5:22 PM, said:

I have this nice 1987 Hitachi TV that works great except the bottom left corner of the screen looks like there is a magnet messing up the color. Could it be the TVs own speaker causing this?? Anyone know of anything I can do about it?

Turns out there is a magnetic field in my basement. If I roll the TV forward 2 feet it goes away. For that matter I can keep it were it is and turn it to the right 90 degrees and it goes away. I have another smaller TV in the same spot is much less sensative to the field.

I can't figure where the magnetic field would be coming from!

[edintv]

Official Ninja, on Tue Aug 16, 2011 5:25 PM, said:

Official Ninja, on Mon Aug 15, 2011 5:22 PM, said:

I have this nice 1987 Hitachi TV that works great except the bottom left corner of the screen looks like there is a magnet messing up the color. Could it be the TVs own speaker causing this?? Anyone know of anything I can do about it?

Turns out there is a magnetic field in my basement. If I roll the TV forward 2 feet it goes away. For that matter I can keep it were it is and turn it to the right 90 degrees and it goes away. I have another smaller TV in the same spot is much less sensative to the field.

I can't figure where the magnetic field would be coming from!

Normally that magnetic fields are from High Voltage cables, do you have that in your basement? you must check it out, there are studies that people who live near Electric cables generate Cancer more frequently, not to scare you but maybe in your citi hall you can find info.

Also stron magnetic fields are caused by elevators but only when they moving.

[Stephen Moss]

Official Ninja, on Tue Aug 16, 2011 5:25 PM, said:

Turns out there is a magnetic field in my basement. If I roll the TV forward 2 feet it goes away. For that matter I can keep it were it is and turn it to the right 90 degrees and it goes away. I have another smaller TV in the same spot is much less sensative to the field.

I can't figure where the magnetic field would be coming from!

I assume the TV is on a table and therefore a couple of feet off the ground if so that would be one hell of a field to penetrate that far, are you sure it is not something nearer like the 7800 (or its power supply if located under the TV) that is the cause of the problem?
The reason moving the TV foward or rotating it solves the problem is it is moves the metalic shadowmask away for the magnetic field and it is the shadowmask being magnatised that effects the colour as the electrons fired at the screen no longer hit the correct coloured phosphor dots.

[edintv]

Stephen Moss, on Thu Aug 18, 2011 1:58 AM, said:

Official Ninja, on Tue Aug 16, 2011 5:25 PM, said:

Turns out there is a magnetic field in my basement. If I roll the TV forward 2 feet it goes away. For that matter I can keep it were it is and turn it to the right 90 degrees and it goes away. I have another smaller TV in the same spot is much less sensative to the field.

I can't figure where the magnetic field would be coming from!

I assume the TV is on a table and therefore a couple of feet off the ground if so that would be one hell of a field to penetrate that far, are you sure it is not something nearer like the 7800 (or its power supply if located under the TV) that is the cause of the problem?
The reason moving the TV foward or rotating it solves the problem is it is moves the metalic shadowmask away for the magnetic field and it is the shadowmask being magnatised that effects the colour as the electrons fired at the screen no longer hit the correct coloured phosphor dots.

I´ve seen that many times in basements (due my line of work), the Magnetic field of a High Voltage cables can affect a Crt in a desk very easy. you should discard any other source, but is very possible.

[Official Ninja]

I'm starting to think it is a defect in the TV that makes it more sensitive than other CRTs.
I can place any other CRT in the same spot and they do not have issue. Right now I have an old 11" Panasonic in the same spot as the picture above and it has no problem. I tried this TV on a desk across the room in place of a Commodore 1702. It had the same issue when placed there. The 1702 shows no signs at all of being in a magnetic field in the same spot.

Honestly, I paid $2.99 for the Hitachi at Salvation Army. I'll just have to keep my eye out for another similar size TV.