Image skewed at the top and I can't stabilize it

richiewoo

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I have a monitor that I've been working with for a while.

I capped it, and improved it by a lot. I still have part of the image skewed and unstable at the top. It gets better when I mess with the H-posi pot on the remote board, but just won't stabilize. I don't understand what could be causing this. It's not the tube, because I did some testing and verified that it stayed the same way at the bottom when the image was inverted.

I'm thinking that it might be related to whatever controls H-position. Problem is, I don't know what that might be on my chassis.

The chassis is a Kortek Ktx26 (K1-2-VO) that was identified in another post. I have pics of the test screen that show it. Where you see the wavy lines at the top of the screen, there's also instability (vibrating of the picture).

Any thoughts at all?

Thanks!
 

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I have a monitor that I've been working with for a while.

I capped it, and improved it by a lot. I still have part of the image skewed and unstable at the top. It gets better when I mess with the H-posi pot on the remote board, but just won't stabilize. I don't understand what could be causing this. It's not the tube, because I did some testing and verified that it stayed the same way at the bottom when the image was inverted.

I'm thinking that it might be related to whatever controls H-position. Problem is, I don't know what that might be on my chassis.

The chassis is a Kortek Ktx26 (K1-2-VO) that was identified in another post. I have pics of the test screen that show it. Where you see the wavy lines at the top of the screen, there's also instability (vibrating of the picture).

Any thoughts at all?

Thanks!

Flaky regulator
 
Care to elaborate on this?

My Neo mobo produces the same exact picture curve as his. I asked Channelmanic about it and he told me the Neo's have a tendency to do this on certain monitors. Adjusting the 50/60hz pot and horizontal position helped mine alot though. It is almost unnoticable.
 
Yeah, it's a Neo

I pulled the chassis to reflow some joints. I asked a guy outside of this forum about this and he said:

It looks like it's haveing trouble re-acquiring sync
after the vertical retrace period.

The bad part would probably be something associated with IC401.

I have two ways of going about this... one is what I've been doing: I pulled the chassis and started looking at everything around IC401 including reflowing some joints. Still working on that. The other is to get another neo geo board and see if it does the same thing. I have another jamma type board that I might be able to plug in to check the monitor so that I can eliminate or confirm the possibility that it's the neo geo MB that's causing this.

What is the chassis in your neo geo, Count? Mine's a Kortek KTX26.

Thanks for the replies. I will keep you posted as to what I find... if anything!

Rich
 
Mine is a WG k7 series chassis. I tried my mobo with 3 different monitors and it did it to all them. It looked just like yours prior to the adjustments I stated earlier. Now in order to see it, I have to go into the test screen like the one in your photo. Otherwise I can't see it in game, it's too small a bend to see with multiple colors and images around the top of the screen.

I was directed by Channelmanic to contact KLOVer ArcadeCup for possible solutions to this issue, but I never did.
 
I have a Neo Geo with the same monitor as the OP and the top half of my picture shimmies left to right constantly. I haven't tried another board on the monitor yet. Interesting to hear Neos having issues with particular monitors.
 
Wow, that sucks!

If it's a NeoGeo mobo problem, it would mean there wasn't much I could do about it, except get another neo geo mobo!

I'll keep working a bit and see if I can get that spare mobo over the weekend to see if I can confirm. Also should be putting the chassis back in tonight after my hopeful joint reflowings.
 
If it's your mobo causing it, which I assume it is, there is nothing you can do about it that I know of. Except trying the 50/60hz and horizontal position adjustments.
 
If it's the mobo

Then maybe there's a cap or two that can be replaced?

There are several in the "sound" area but maybe a few are video related?

Ever take a crack at that? I have 6 of the many caps and am thinking of replacing them for kicks, but am still waiting for that test board to be sure.
 
Called it! No really thought it o.k. Just make adjustments to the 50/60hz and hor. position and it will prolly get better. And honestly, is it that noticable in games?? Heres a pic of mine in the test screen as it sits now. When I got the mobo, it looked as bad as yours if not worse..... so make carefull adjustments.
 

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And sorry, I realized you were talking about caps on the mobo. I replaced all the audio caps on my 1 slot mobo and the backup battery. This obviously had no effect on the issue.

There are several (3?) 470uf caps near the audio section which aren't part of the audio secction, but I don't know what they are for.
 

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Damn mobo

I can't get it to a good consistent spot. I adjusted the 50/60 pot and others, but I think it's still unacceptable. I'll either get a different mono on there or replace so
e of those 470 caps to see if that helps. I'll let you know if I somehow manage to fix it.

Thanks for all the input! At least I can stop pulling the chassis and secong guessing myself.
 
Did some caps on the mobo

Still not good. There are a few more that I need to do, just need the time to do it.

I'll let you know if I somehow manage to fix it.
 
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