WG 25K7193 foldover

debaser138

Well-known member
Joined
Mar 1, 2009
Messages
1,029
Reaction score
64
Location
Grand Rapids, Michigan
I've got a WG 25K7193 that I've rebuilt with new flyback, caps, etc. Monitor works but has a couple of issues. First off, the left hand side of the screen has a thin vertical white line from top to bottom (monitor is sitting horizontally). Adjusting the horizontal position pot doesn't move the line.

The other issue is that when adjusting the horizontal position pot to the far right (like on a crosshatch screen so it's easy to see what it's doing) it folds over on it self. If I move the horizontal position pot for the far left, the left side doesn't fold over and it just goes off the screen as normal.

I can adjust the horizontal position pot so that the crosshatch pattern is perfect on the screen but it's odd that it folds over on the right like that when adjusting it to the extreme right.

Any ideas?
 
have you adjusted the horzontal width coil behind the fly.

your width cap may be going and is out of spec.
check C36 and see what its value actuly is it could have drifted out of spec.

also check your horizontal position jumper and see if it is off set. if it is put it on the center post and see what happens.

that is where i would start.

Peace
Buffett
 
have you adjusted the horzontal width coil behind the fly.

Yes, I've adjusted that.

your width cap may be going and is out of spec.
check C36 and see what its value actuly is it could have drifted out of spec.

I'll take a look at that. I think I might have some new ones in one of my parts bins. Just gotta find it.

also check your horizontal position jumper and see if it is off set. if it is put it on the center post and see what happens.

Yeah I've adjusted that as well.
 
Finally getting back to this monitor chassis after being busy with other projects. I've tried swapping out the critical safety cap C36 but that didn't make a difference.

The thing is, on my test bench using Jrok's Multi-Williams board as my test board, the horizontal size is great and no fold over on the right hand side. I do still have the white vertical line on the far left hand side.

When I hook it up to my Neo Geo machine (which the monitor is originally from) the horizontal size is way too big and the screen is folding over itself on the right hand side. I adjusted the horizontal width coil but it doesn't shrink it enough to make a big difference. If I adjust the horizontal position pot, I can get the screen to not fold over on itself but then the picture on the left side is extended off the screen (still have the white vertical line on the left as well). The horizontal center jumper near the width coil is in the center.

Looks like something is going on in the horizontal section of the chassis. I've looked at a few of the resistors near the horizontal width coil but everything looks good.

Anyone ever seen this before or have any ideas what else I should check?
 
You could try increasing your horizontal width range by changing out the width cap, to see if that has any effect on your white line...
 
When I hook it up to my Neo Geo machine (which the monitor is originally from) the horizontal size is way too big and the screen is folding over itself on the right hand side. I adjusted the horizontal width coil but it doesn't shrink it enough to make a big difference. If I adjust the horizontal position pot, I can get the screen to not fold over on itself but then the picture on the left side is extended off the screen (still have the white vertical line on the left as well). The horizontal center jumper near the width coil is in the center.

My Neo Geo does the SAME EXACT thing. I also have a 25K7193. I have been meaning to look at it, but I've had other problems with this 25K7193 and I have been slow at looking at it.

Here's the annoying thing in my situation - it did this with the Kortek chassis that was originally on this monitor. So two different chassis on the same monitor with the same problem, only thing that's the same is the game. I got this 25K7193 to get rid of this problem, because I couldn't repair the Kortek because there is no parts list or replacement parts.

Adjusting the horizontal coil gives me a smaller size screen, but even if I shrink it down it still folds over. Even if I shrink it down so it only uses a part of the screen, it still folds over on the right side.
 
You could try increasing your horizontal width range by changing out the width cap, to see if that has any effect on your white line...

I did try swapping it out with a bigger cap and that did bring the horizontal width size down but I'm still getting the white vertical line on the far left hand side along with foldover on the right hand side. If I adjust the horizontal position while on the Neo Geo test screen, I can get rid of the foldover but some Neo Geo carts must have a different signal as some of them have foldover again on the screen.
 
My Neo Geo does the SAME EXACT thing. I also have a 25K7193. I have been meaning to look at it, but I've had other problems with this 25K7193 and I have been slow at looking at it.

Here's the annoying thing in my situation - it did this with the Kortek chassis that was originally on this monitor. So two different chassis on the same monitor with the same problem, only thing that's the same is the game. I got this 25K7193 to get rid of this problem, because I couldn't repair the Kortek because there is no parts list or replacement parts.

Adjusting the horizontal coil gives me a smaller size screen, but even if I shrink it down it still folds over. Even if I shrink it down so it only uses a part of the screen, it still folds over on the right side.

If you adjust your horizontal position pot on the remote board, can you get rid of the foldover?
 
my neo geo mvs2 also does the same thing. my monitor is original and a k7193 as well. I would love a solution to this. also, no matter what the top is not 100% even with 50/60hz pot and is annoying especially with games like 1945x. I did exacly what da66en did for now.
 
If you adjust your horizontal position pot on the remote board, can you get rid of the foldover?

I haven't tried this in a few months. But IIRC, if I moved the horizontal position the foldover moved with the position. If I adjusted the hcoil, the width of the picture changed but the foldover was still there. The only thing that really seemed to affect it was the horizontal hold adjustment - if I adjusted that then the foldover would move from the right side to the left side.

Did you play with this anymore?

Did you get a chance to test your chassis on a game that isn't a Neo Geo?

Thanks.
 
I have the same issue as well but only when using my neo geo. monitor is 100% when play jamma boards like mk3, street fighter etc. this is currently in a dedicated mk1 cabinet.
 
I have the same issue as well but only when using my neo geo. monitor is 100% when play jamma boards like mk3, street fighter etc. this is currently in a dedicated mk1 cabinet.

So, maybe the Neo Geo is at fault for us?

Going to bring my oscope home from the office and check the RGB and sync signal coming from the game - hopefully those are documented in the 25K7000 manual. If not, does anyone have suggestions what to look for on those signals?
 
Someone one neo-geo.com suggest adjusting the horizontal phase. Is there such an adjustment on the K7100? If it's not an adjustment pot, anyone know where on the schematic this is handled? Maybe a cap there needs to be tweaked?
 
I'd like to add to this old thread and say I've suffered the same issue with my neo geos. I've got a 2 slot cab and a 4 slot cab. They both produce the same 'too wide' situation. The only thing I've managed to do is swap the width cap to get any results somewhat close or not good enough. The thing is, you do get a narrower pic, but it doesn't totally eliminate the fold, just makes it thinner and harder to see. I have thrown 3 different types of monitors at it. A Kortek pulled from a neo geo, a k7000 that came in the 2 slot cab, and a pentranic dual sync. All have the same fold issue.

It would be awesome if a mod could be made to accomodate the neo geo, but I haven't seen anything... I've spent sooo much time tweaking and hoping for change but no joy...
 
I never found a solution to this. It's definitely related to the Neo-Geo, other games don't have the same problem on the same monitor. I used a CGA to VGA adapter on the Neo-Geo and I don't remember being a problem - but the adapter might be smart enough to work around any timing flaws. I was also bored one day and looked at the RGB from the Neo Geo on an oscope and the timings looked OK, but it could be something subtle like a slow rise or fall time.
 
Back
Top Bottom