I've asked this before, but... VERY discolored monitor

So, I get a massive discoloration on my tube... stop, it's NOT degaussing (but keep reading).

No matter what I do, I can't get the weird colors off the tube. I can shift the problem around with a degaussing coil, to be sure. In other words, it's not just a big red blob in the same spot that won't go away... I can move it to the other side of the monitor, or whatever. It LOOKS like a magnet issue for sure.

So I wonder, what the hell is this? I degauss it all day long, and it never goes away. Here's something, it has a little degauss switch on the panel that you control color and size and all that with. When I press it, it sort of makes the picture look like it will become better, but then it just makes it all bad again.

Could it be that whatever electro magnet that it comes with is screwing up the color on this? There's no magnets of mine anywhere, no interference (I say that because it's been in two different machines, and in NO machines... all having the same issues).

It's a Makvision 24.8 monitor that I bought new about six months ago, and never was able to return it. Everything on it looks great but this. What the hell could this problem be?

Did you try degaussing?

madman said:

Did you try degaussing?

Click to expand...

he said in his post he has bolth used a wand and the built in deguass tool

just locate the wires for the built in deguass on the monitor and disconnect them amd then use your deguassing wand and see if that fixies it
there may be a short on the built in deguasss tool or it may be wired wrong causing the magnet to be on all the time

also check inside the cab are there any wires coiled up around the monitor if these are powerd wires they can create a mini electro magnet (esp if they are not sheilded wires)

check the speakers in your cab make shure they are original and have not been replaced by unsheilded ones

is the monitor chassis grounded properley


you might want to ask your ? over at the klov forums they are a more specialized forum for arcade machine repair

http://www.klov.com/

He said in his post that he tried it in 2 cabs and no cab, so it's certainly not the speakers.

I was joking about the degaussing, BTW. It was his first sentence.

If you are using a wimpy 10 dollar degaussing coil or stick from eBay then you may have to move to something more stout.

Beyond that, if the mask inside the tube slipped they you are fucked.

Okay, I showed this to the guys at KLOV (great suggestion, discgolfer... and they said to adjust the yoke back and forth. WONDERFUL IDEA! What the hell does that mean? How do I DO that?



There it is. What to I do, anyone? What parts should I NOT touch?

This sounds scary, and it is, in two ways.

#1
That fat red cable in your photo is the anode wire, you definately don't want to pull/touch/play with that while the monitor is on. (There is high voltage on it that can kill you.) (see monitor discharging 101 on internet..)

#2
The yoke is the whole thing sitting on the neck (thin part) of the tube..
If you manage to break the neck of the tube trying to get the yoke off, it would implode, sending shards of glass into your body.

The reasoning behind the discolouring is sound though.
The yoke (thin copper wiring under the black tape) controls where the beams hit your tube. It's like a magnifying glass, and could be out of focus in the center, causing too much of a certain 'colour' beams to hit the center, which in turn causes the effect your seeing.

If you do manage to loose the yoke, you would need someone to watch the front of the tube as you adjust it, then use the small pegs+glue to keep it in place. A really tedious job..

The yoke is adjusted in the factory normally to have correct output. You can see those small pegs wedged between the yoke and tube, those are glued on so that the yoke stays in place. Perhaps one of those pegs fell out ?

This picture explains more clearly:

- Black things on top of neck: convergence adjustment (under white (tape?) on your tube)
- Metal strip+screw: holds yoke in place
- Copper wires: yoke coil part (this they want you to move up/down the neck.)
- Pegs+glue: factory adjustment to keep coil centered/in place etc.

Basically these are the steps:
- Remove neck board (pcb)
- Unscrew the part that holds yoke coil in place (metal strip+screw)
- Move yoke coil away from the tube a bit
- Re-screw
- Ensure pegs keep coil in place.
- Re plug neck board. check picture. etc.

If you have no experience with this, i suggest another monitor.. there are people that go and move around the whole yoke assy from one tube to another for a living, but it's a potential dangerous thing to attempt if you've never done it before.

Marry xmas!

undo the yoke clamp screw and seperate from the glued wedges between the yoke and CRT. If you are not sure what you are doing you are likely to end up with a worse purity error. If may even be the CRT itself faulty.

Tip- ground the red cathode via a 4.7 K resistor (not critical), that will give you an all red screen to play with. The problem with shifting the yoke is that it does not only adjust purity but convergence as well.

Edit-Asure, the pic you posted is of an older gen CRT with adjustable convergence and purity magnetic rings. Spikes is later gen without those physical adjustments.