Purple discolorition in one corner, only when facing South

[TheRetroCarrot]

So I picked up a KV32S42 off the original owner a few days ago with the plans of using it for consoles. However after playing around with it for a bit I decided to put it in an arcade cab and just save the housing in case I ever want to revert it to it's previous pristine form. The display overall looks excellent however I have purple discoloration in one corner only when the TV is facing South, tilting it even a couple degrees makes this worse as well which I noticed since I originally had it on a drop cloth to drag it around. Facing North has no issues whatsoever. Tried manually degaussing with an external degaussing coil, this area gets a fair amount of discoloration during the process and can go away mostly, but always comes back as soon as the buttons lifted.

This set does have a metal shield behind the display so it's possible I could correct this with some small magnet placement. However I'd rather not if possible as that seems a bit hokey. I currently have all the boards out of the set to attempt an RGB mod (my first one, my brain hurts from all the reading), any particular areas I would want to look at? I wouldn't think a failed capacitor would cause something like this but my knowledge of CRT technology is base level.

Image of the issue:
https://i.imgur.com/OhqWohQ.jpeg

Service manual if anyone is interested:
https://www.manualslib.com/manual/10224 ... 32s42.html

Thanks in advance!

[thchardcore]

You need to add a chevron magnet to that corner to fix it.

[TheRetroCarrot]

Sorry what's a chevron magnet? I have a bunch of magnets around here of various sizes and strengths. I'm really wondering why one corner would be so strongly affected by which direction the set is facing when nothing else is, I can't say I've ever run into that before and I've owned something like 30 CRTs in the last 10 years.

[SavagePencil]

Degauss that bad boy

https://youtu.be/j1lDedDZcw0?si=REul-24CDM1jcn4z

[TheRetroCarrot]

Degauss that bad boy

https://youtu.be/j1lDedDZcw0?si=REul-24CDM1jcn4z

Done it probably 10 times, just comes back as soon as I finish up. Only way it goes away at the moment is facing the set North. Doesn't matter the location in the home either.

[SavagePencil]

Are you pressing the Degauss button or using an actual degaussing coil?

I remember that a plugged in soldering iron can work in a pinch, too.

[TheRetroCarrot]

A Waldom 9317 external coil.

[Syntax]

https://www.manualslib.com/manual/10224 ... =12#manual

Has a disk magnet fallen off the tube?
Looks like purity control only does the outside edges not corners.

[TheRetroCarrot]

This feels like a very good thing to check, I actually haven't removed the shield from the back of the tube yet, I'll do that and take a peak.

[TheRetroCarrot]

I took a peak and it doesn't appear to be the case. There are 3 very weak magnets positioned circled in red, then 4 foam blocks that I'm guessing were just there to position during manufacturing as they don't have tension anywhere, one of those fell out of the left marked with a blue X I reattached. Problem area circled in purple. It's possible there was a magnet there at one point, but I've disassembled this entire thing and cannot seem to find one anywhere.

[Josh128]

To fix, power the set on in the desired orientation, and experiment with a magnet in different positions in the back. I like the 1cmx1.5mm round neodymiums, they are stackable and can be positioned on edge (using putty, tape, and silicone glue) if needed. I find these are the sweet size for neos- dont go larger than that. For ferrite magnets, you can go quite a bit larger, depending on the strength.

[TheRetroCarrot]

To fix, power the set on in the desired orientation, and experiment with a magnet in different positions in the back. I like the 1cmx1.5mm round neodymiums, they are stackable and can be positioned on edge (using putty, tape, and silicone glue) if needed. I find these are the sweet size for neos- dont go larger than that. For ferrite magnets, you can go quite a bit larger, depending on the strength.

I finally got around to experimenting with this a bit. It's very easy to remove the discoloration, the problem is as soon as the TV is cycled and degausses it reverses the correction done from the magnet. Am I missing something obvious or is there a trick to make this last? The service manual does state to use magnets for corners, and yoke position/purity rings for the rest of the screen.

[Josh128]

The magnet that fixes it is still in place and the spot returns after a degauss? What kind of magnet did you use? It sounds like its degaussing the magnet lol. A neodymium wont degauss, so as long as its in place the spot should not return.

[matt]

I finally got around to experimenting with this a bit. It's very easy to remove the discoloration, the problem is as soon as the TV is cycled and degausses it reverses the correction done from the magnet. Am I missing something obvious or is there a trick to make this last? The service manual does state to use magnets for corners, and yoke position/purity rings for the rest of the screen.

That means the magnet is too close to the edge of the tube. There's usually a "sweet spot" for purity magnets where they don't get canceled by the degauss but also don't affect geometry. Try moving it away from the edge and see if you can find the right spot.

[TheRetroCarrot]

Ah very interesting, I'll experiment a bit and with different types. I was using very small neodyms, though I also have your standard fridge magnet streps similar to what is on there from the factory.

This set actually has a shield (not pictured) on it which I was sticking the magnets to directly as a test. Not sure if that would have any effect on the magnet getting degaussed? If not it sure makes it handy.

[Guspaz]

My 14" PVM had blue discolouration in one corner, no amount of degaussing would fix it. So I went to the art supply store and bought a whole bunch of strip magnets, found the place on the tube where it helped, and stacked them up until I was satisfied with the amount of correction, and then duct taped them in place. It's been fine for years now, probably the better part of a decade.

[matt]

Ah very interesting, I'll experiment a bit and with different types. I was using very small neodyms, though I also have your standard fridge magnet streps similar to what is on there from the factory.

This set actually has a shield (not pictured) on it which I was sticking the magnets to directly as a test. Not sure if that would have any effect on the magnet getting degaussed? If not it sure makes it handy.

Sticking it to the shield should work well enough. Taking the shield off is so much trouble that I'd want to try other avenues before removing it!

[TheRetroCarrot]

Ya it's ideal because it's going in an arcade cab, being able to shove a magnet here and there once in it's final home will be much easier with the shield. Getting underneath it will be a monumental task once it's installed. I'll play around with it a bunch once it gets to its final resting place, it's elsewhere in the house so there isn't much sense doing too much where it is and then moving it.

EDIT: Been playing with this some more, frustratingly it seems no matter where I place magnets, it always undoes my correction as soon as the display is powered back on. Does anybody have any other ideas? This was for a big rotating display cabinet, so it being able to degauss successfully with decent purity is mandatory. The build is fairly far along. The only other 32" locally that is available is a JVC D series, but the guy wants $250 for it.

[TheRetroCarrot]

So my initial assumption that the degauss was undoing the correction done by magnets was incorrect. Even with the degauss coil inactive a power cycle will always bring back issues in the same areas, if you remove the magnet after powering on the purity issue is doubled. It seems like something is causing areas of the screen to be magnetized every time it is powered on... a manual degauss does not correct it either.

[jd213]

Have you tried it without the shield? I've seen PVMs with the shield itself magnetized and causing purity issues.

[matt]

Have you tried it without the shield? I've seen PVMs with the shield itself magnetized and causing purity issues.

I had one PVM where the outer case was magnetized. I was able to fix it by using degauss coil on the case itself (after removing it and putting it in a safe location).

[TheRetroCarrot]

Have you tried it without the shield? I've seen PVMs with the shield itself magnetized and causing purity issues.

This is something I actually considered after playing around with it the other day. I haven't tried without the shield yet, but I'd imagine I could clear it with my degauss coil if it is after removing it.

I'll give that a try when I next open it up once my cabinet is built.