Help with CRT Geometry Issues

[dedmunds]

Hi folks,

I have a monitor and Chassis set in my Donkey Kong Cab that has some issues. It's playable, but the geometry is pretty out of whack.
Note: LHS of that bottom girder is meant to be flat. as you can see it curls up a bit.

The projection onto the monitor actually curls up on the bottom left and right, and kind of has a bullnose curl when it is just powered on, which goes away after 15 mins which i figure might be vector caps on the chassis somewhere. 

The top right also has a bit of a dip in it. You can tell by the high score text has a lean to the right

Has anyone had any experience playing with geometry and do they have any tips of hints go get me started with it?
I'm not that keen on playing with it tbh but it is either that or swap the monitor and chassis set over, and cbf with that either if it isn't too difficult-a-process 😄 

It's a nice crisp clean picture but yeah those girders ain't exactly straight haha. Could it be that this is not a very well matched CRT and Monitor Chassis? I was wondering if the chassis isn't 100% compatible with the tube and yoke it might be outputting a bad picture.

Love CRTs but far out they're a pain sometimes...

CRT details

Chassis details

Thanks folks,

[IZ8DWF]

Well,  that doesn't really look like the monitor isn't suited for the game output... Bad geometry like that could be caused by different issues. Is the monitor chassis "original" to this particular CRT and yoke? Or is it a "frankenstein" monitor (made from different monitor's part)? Notice that's it is generally ok to swap the CRT on a chassis, but you usually must retain the original chassis' yoke.

However, you should really enable some test mode on the game PCB that displays a chessboard or cross-hatch pattern, then we can discuss some options. Also it would really help to know what is the monitor chassis, so maybe looking at its schematic helps in giving any sensible suggestion.

EDIT: just found the schematic based on the label you posted...

HTH

Frank IZ8DWF

Edited June 19, 2022 by IZ8DWF

[con]

i think its the wrong tube? kaga chassis should be paired with mitsubishi tube?

Obviously Jomac would be the person to speak to

[buttersoft]

Joey always said all the 10-pin tubes sold for arcade use in the his country were the same 2R/~50R configuration, if it helps. I don't think you'd get the picture that close to good with a mismatched yoke.

[MarkOZLAD]

If it helps...I bought a cab for my friend and it had exact same chassis and tube combination in it.

It also had a pincushion issue,  bowed in the opposite way.

[dedmunds]

Hi guys

Yeah a friend that is an electronics engineer said the monitor and chassis pairing would work fine.
@jomac - Hi Joey, did you have any advice or can you recommend a universal chassis if i send you the V and H measurements of the yoke + photo of the neck?

Cheers everyone for the responses 👍

[dedmunds]

That's the test pattern from my Neo Geo 1 slot in the cab... Wow.

[Gemini2544]

I emailed Joey last week about seeing if he still had those Universal Chassis, He responded that the factory he was getting them from closed down & he had none to sell. He also added that if he could get them again he'd be selling 10 a week due to requests. Hope this helps.

[dedmunds]

Hey again guys thank you for the help, I ended up buying a replacement CRT and Chassis to chuck in the cab. It will be fine until i can locate a decent replacement for the KZ-20 chassis. It works, but I just dont think that its suitably matched to the monitor.

Cheers

[Gemini2544]

I found an old Photo of my 20" upright, anyway this is the image of it's geometry. Hope it is of help!