1988 Sony kv-p14d trinitron CRT repair

[Nicolas 2000]

This is a 14 inch compact housing PAL trinitron with SCART, ideal for my RGB modded computers. But, something is wrong. The screen is tilted and the sides discolored. Would this be the yoke that got loose and moved away from the tube plus tilted?

(Ignore the dark horizontal bands and moire, those are photo artifacts)

Or could something this extreme be a matter of just needing degaussing?

 

[Chuck(G)]

I'd try degaussing first.

 

[Nicolas 2000]

I don't have a degaussing tool. I'll check if the built in degausser works and if not try to repair it if I can find a replacement posistor.


Any diy solutions I could safely try on a trinitron? I have a corded drill, another crt, a 50kg fishing magnet, speaker magnet...or something I could build?

I have seen the color issue solved by people on their crt before with degaussing. Not sure about the tilt though.

 

[pbirkel@gmail.com]

Perhaps start here:

https://www.instructables.com/Homemade-Degaussing-Coil/ (assumes that you have an old coil from a CRT)
http://www.kerrywong.com/2010/01/18/building-a-degaussing-coil/ (simple to build, more complicated to use)

http://www.eiwellspring.org/tech/Degausser.pdf

There are many other sources.

IMO start by degaussing. Then you may need to adjust the yoke coil unit a bit to correct the tilt.

 

[Chuck(G)]

For tilt, check the position of the deflection yoke. Looks as if yours may have moved. It may also contribute to the chroma problems. Said yoke usually has stubs with magnets mounted for color correction.

 

[VERAULT]

Definitely a degausse issue. Another member here posted about storing old monitors against the concrete foundation of your home would cause slow longterm effects like this.

I have come across a few trinitrons in similiar screen coloring. My repair was swirling a rare earth magnets in front of the screen at verying heights and pulling away in the sides or corners it was worst. IT works with practice.

Keep in mind if you dont do it properly it will make it worse.

 

[Nicolas 2000]

That's why I think it might be safer with the internal degausser. Also, how strong a magnet would be suitable?

 

[Chuck(G)]

Align the yoke first--the results may surprise you.

 

[Nicolas 2000]

I saw a youtube video with very similar effects due to a shifted yoke. Others said not to touch a trinitron yoke or you'll never get it right, but I think they mean individual rings where I would only move and rotate the entire yoke unit as a whole.

If I have time -might take a week or so- I'll take out the tv, check for degaussing noise, open it up and check the yoke position.

 

[Chuck(G)]

The Trinitron is different from standard shadow-mask jugs. Yoke positioning (as a unit) is pretty critical.

 

[Nicolas 2000]

Which means it's a risk to move it, but also that if it is shifted now, it must be placed back in position to get the tv to work properly.

Any do's and don'ts to move the yoke? Undo the screw at the back, only touch plastic, rotate to correct tilt, shift forward into position. That's all I know about it, in theory that is. Never repaired a crt before.

 

[VERAULT]

That's why I think it might be safer with the internal degausser. Also, how strong a magnet would be suitable?

I use the ones out of defunct hard drives. Strength doesnt matter as the rare earth magents are all very strong.

 

[VERAULT]

Align the yoke first--the results may surprise you.

You think its a convergence issue?

 

[Chuck(G)]

Just pointing out that Trinitrons don't work the same way as 3-gun shadow-mask units do.,

Have a look at this

 

[VERAULT]

Oh I know, its very true. I had the fun of troubleshooting convergence and color bleed issues on some pretty beat trinitrons. But This looks like exposure to significant magnetic fields.. Especially the upper left. But you are right. check all the obvious things before taking another magnet to it

 

[Hugo Holden]

A TV's internal degaussing coil does not have a strong enough field to fully degauss a CRT. The field is too weak.

It requires a line powered hand degaussing wand (these are cheap) you have to energize it (button on) and waive it around the CRT perimeter from the front and slowly move it away, The decaying alternating fields result in zero residual magnetism. Do it on the middle of the living room table, not in your workshop that may contain magnetic media. Only approach the screen from the front, don't waive the wand anywhere inside the cabinet.

Don't move the yoke until after degaussing. It may not be required.

Also note that many Trinitron sets have a raster rotation coil on them, so that you don't have to mechanically rotate the yoke, to rotate the raster. This is often an option in the settings.

Don't put any permanent magnets near the CRT, there will always be a fixed field left and you will make things worse.

 

[VERAULT]

A TV's internal degaussing coil does not have a strong enough field to fully degauss a CRT. The field is too weak.

It requires a line powered hand degaussing wand (these are cheap) you have to energize it (button on) and waive it around the CRT perimeter from the front and slowly move it away, The decaying alternating fields result in zero residual magnetism. Do it on the middle of the living room table, not in your workshop that may contain magnetic media. Only approach the screen from the front, don't waive the wand anywhere inside the cabinet.

Don't move the yoke until after degaussing. It may not be required.

Also note that many Trinitron sets have a raster rotation coil on them, so that you don't have to mechanically rotate the yoke, to rotate the raster. This is often an option in the settings.

Don't put any permanent magnets near the CRT, there will always be a fixed field left and you will make things worse.

You are not wrong at all sir. Good advice to people. But I dont own a degause coil and have repaired similar screen problems with magnets. Again im not advising folks to do this willy nilly.

Has anyone ever used magneta in this way?

 

[Chuck(G)]

In any case Here's the service manual

 

[Hugo Holden]

You are not wrong at all sir. Good advice to people. But I dont own a degause coil and have repaired similar screen problems with magnets. Again im not advising folks to do this willy nilly.

Has anyone ever used magneta in this way?

These economical wands work really well, though they are 220V:

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There are some CRT's which become so heavily magnetized that only the wand will do it. Usually the thing that causes it is proximity to speaker magnets which are powerful ceramic types. Although interesting things happen when a CRT set is moved between Northern & Southern Hemispheres, including raster rotation.

 

[Chuck(G)]

For what it's worth, I've used hand-held videotape bulk eraser to degauss CRTs. If can get degauss a 1/2" videotape, it's got to have a pretty strong field. I used it the same way one would use a degaussing coil--start close and gradually move away using a circular motion. Worked a treat.
I don't know how common they are today, but this is the model that I have. (1100 gauss)