CRT TV/Monitor Repair & Troubleshooting

There has been quite a bit of talk lately on the consumer CRT thread about TV issues, and I thought it would be a great addition to the board to have a general CRT resource, repair and troubleshooting thread.

Let me start of by saying that I’m not an expert in this subject. I find it very interesting, and I am learning, but I’m probably not as knowledgeable on the subject as quite a few others on this board.


  • This is a 4 part series. It’s an excellent class on casino monitor repair, and a must watch for anyone that wants to repair CRTs. It’s very in depth, and close to 8 hours long. I cannot recommend it enough.


  • Discharging the high voltage in a CRT.

  • A short video explaining the diagnostic and repair process of a CRT, without documentation.

  • Using convergence strips to adjust for convergence issues on a CRT.





  • TV Repair Guide - Large website dedicated to general repair.

  • Large PDF focused on CRT arcade monitor adjustment.

Please add your own resources below, and I can move them up into this 1st post.


Great post! I’ll stop cluttering up the consumer thread with my issues and post some progress with the convergence issues I’ve been having with my Sony Trinitron KVXA29M31;

As you can see from the images the entire tube has convergence issues, it does get worse towards the corners of the set but even in the center there is considerable ringing. Sadly this particular model does not have any convergence controls accessible through the service menu, instead I’ll have to open the unit up and tweak the HSTAT and VSTAT magnets and eventually the convergence strips to rectify the corners.

I’m waiting for a friend of mine to come over to give me a hand eyeballing the adjustments while I make them, I’ll be sure to update the thread with my progress.

PS please ignore some of the clipping at the top of the second image, the only console I have with a component output and 240p test suite is my PAL PS2 and it has some rather severe compatibility issues with the homebrew.

Edit: Well after an hour or so of tinkering I’ve been able to get the center of the image pin-sharp, the issues still remain with the corners and its clear that the convergence strips on the set currently have nearly no effect on the corners of the image.

That said it looks like this may be all for naught, as after focusing the tube what I thought was a tiny VHS like artifact on the bottom of the screen is about five or six flickering lines that only appear in 60hz mode and in some games it is very distracting, there are no issues when running the set at 50hz. So I might end up throwing this up on Gumtree after all :frowning:

Here’s another convergence fixing example. It’s fairly common to use strips with a Blast City

1 Like

Thanks, I’ve added a video tutorial in the OP about this!

I have a 27" Sony Trinitron (unsure of model) that I use for all my non-HD consoles. The picture looks great except that I get faint horizontal bars of static that slowly move up the screen. The bars are more intense on certain input channels than others, but all are affected . I can get pictures of what I am talking about, but any ideas on how to fix this issue?

Sure, get us photos, it would probably help

Adding this to the OP.

1 Like

Awesome. Waiting on a new remote for my 310 before I jump into the service menus. I’ll report back here instead of the consumer crt thread!

I guess this is sort of related. Wondering if there’s anything you can do about scratches on the glass of a CRT? I have a couple of small scratches that are mostly not noticeable on my screen, but when I do notice them it’s hard to not notice. Would be great to get them off somehow. Is that even possible?

I have heard of people peeling off the anti-glare layer (if the TV has one) to reveal pure glass, but it’s a risky thing to attempt. For the most part, the consensus is that it’s not repairable.

Adding this to the main OP:

1 Like

Hmm alright that’s a shame. I did some googling as well yesterday and came across that suggestion too. Since it’s not too noticeable, especially when the TV is on, I’m probably not gonna bother doing anything.

I also read some suggestions for taking it to a car glass repair place, since they’re able to fix scratches on car glass. That sounds plausible but I don’t know how they actually fix those scratches. Since there’s a vacuum behind the glass on a CRT I’m thinking it’s probably quite risky.

Yeah, they could probably do it, as the process makes sense, but if I was the owner of a glass shop, there’s zero chance I would touch it. Not worth the risks.

There’s also still the question about the coating (if there is one).

Here’s a question;

Does anyone know at what voltage I would hook up the degaussing coil wire on a 19” wells Gardner?

I’ve rewired an old cabinet a while ago, but skipped the degaussing cable and the screen color has been off for a while.

I can’t find any info on this for some reason. Does this run from one of the power supply voltages (5,-5,12) or directly from the AC current?

There’s a post here, where a person mentions using a coil out of an old TV to degauss monitors.

In a TV repair shop, we’d use degaussing coils stripped out of old TVs. They can run for 10s of seconds on 110VAC before getting too hot.
Or use a cassette tape head demagnetizer, the 120VAC wand types.
Or use an AC solenoid. A Variac can throttle it down.
For really bad stuff, where the CRT frame or mounting hardware is stubbornly magnetized, I have actually used a magnet first.
Yes, a magnet and you try guess where to move it around to null the original magnetic field. Like pulling dents from a car, guess how it was hit and do the opposite. But waving a magnet around. Not super close unless the corners are stuck. Not near Trinitron neck convergence magnets.
Then use the usual AC field to degauss.

Wow great find. Thanks!

@raskulous thanks for this thread. I watched the 4 part videos of Randy Fromm’s & they were great, I now know roughly what is wrong with each of my broken monitors/TV’s. I would recommend these videos to anyone who dreams about fixing their CRTs. Mind you I have to rewatch part 3 & 4 as it’s pretty heavy going!

If anyone is interested Randy is holding a 4 day CRT repair class in the Netherlands in November!
Link to his site:

I’m thinking about going myself. I spoke to him & he has also said that if we could get a bunch of us together he would consider holding a class in the UK !!
I’m certainly very interested, anyone else ?


Yeah those videos are amazing. If I was able to attend one of his classes, I’d love to.

I watched a few of his videos on youtube and they where very useful.

Shame the 4 day course is so expensive as I’d be up for it otherwise and it does seems pointless to be paying “extra” for equipment you get to keep when you already have most of it anyway.

That said if he came to the UK that might swing things for me.

This is so awesome. How did I miss this post before?