New 21" CRT not displaying properly

Longy

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Hi,

I have a Wei-Ya 2620H chassis, and have managed to get a picture on my 21" chunghwa tube. To be fair the picture is good some of the time, but never consistent. I have read that this chassis is good for 19"-20" tubes. The tube I have is 21". I contacted Wei-Ya about this and they were confident that the chassis is compatiblw with my tube. Despite this, I still have some issues that will not go away:

1) The brightness appears to vary depending on how much light and dark colours are on the screen at any one time. This has a similar effect to someone adjusting the brightness subtley as onscreen graphics change. If for example the screen was composed of 25% white, 75% black, if the screen then changes to display 50% white and 50% black, the white has less intensity than before (it becomes dim). This has a similar effect to someone turning down the brightness when the lighter colours dominate the screen.

2) As the the chassis does not allow you to adjust H-stretch, most games have about a 1" black band at either side of the screen (left and right when orientated horizontally). This doesn't bother me much at all, except that the edges quiver and distort depending on what is happening on the screen. This is quite off-putting when playing games.

3) Certain games display perfectly crisp and sharp - e.g. ghouls 'n ghosts. But others do not display sharp at all no matter what resolution I select in MAME.

I used to have a Hanterex monitor and chassis previously and never had a single problem with it until the day it died on me (a sad day). Whereas I feel I've done all I can with the Wei-Ya chassis, and still have issues. The chassis and tube are both brand new!



I'm very close to just buying another monitor and chassis out of pure frustration. If you have any idea why the above problems are happening, I would love to know.

Thanks,
Alan.
 
Issue maybe from MAME.

You are using this in a mame cab? Have you tried that monitor in a jamma cab?
If so are there any differnces?
 
Thanks for the reply guys.

I've tried using different versions of MAME and different Frontends also - TurboMame, MameUI, Mame32, ArcadeOS, MameWah. Still doesn't solve the problem.

Is it possible that this monitor just doesn't support certain CGA resolutions that other CGA monitors might (my Hanterex CGA monitor did)?

As for the brightness increasing and diming - I've tried adjusting Screen and Brightness (compensating one for the other) but still no luck.
I might try my older Hanterex tube with the new Wei-Ya chassis, just for the sake of checking if there is an improvement over the Chungwa tube.

If any of you have experience with Wei-Ya, can you let me know if they are a good brand (reliable, good picture quality, well built...) compared to other makes such as Hantarex and Wells Gardner etc.

Finally, I should mention that I have an ArcadeVGA graphics card for MAME, but have tried a genuine Jamma game board also, but still have the same issue. Dissappointing.

Thanks,
Alan.
 
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Most universal replacement chassis like Wei-ya have a (N) narrower & (W) wider width range selection jumper wire on them.
 
I almost solved the problem - but not quite. At least that is to say that the picture quality is now about about 7/10.

On the neckboard pcb, there are 3 dials to control the level of Red, Green, Blue, and on the chassis mainboard there are another 3 dials for Red, Green, Blue gains. I turned the lot of them down as far as they could go. I noticed that the RGB's were firing too intensly in the tube, so much so that it was distorting the picture and 'bleeding' into the adjacent area, so that the picture appeared fuzzy. After adjusting all of the RGB controls down as far as they would go, there was an obvious lack of blue in the picture, so I adjusted the blue back up a tad to give a nicely balanced colour range. This had the effect of sharpening the overall picture, and I no longer have an issue with jagged lines either.

I've attached a pic of the finished article. I would have attached more pics, but it was hard to get photos that didn't have exagerated screen inteference. This interference is not visible when viewing the screen in person.

Thanks for all you help.
Alan

Afternote: See my additional on later post regarding issues with colour balance and full-screen whites.
 

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As far as the brightness issue I remember seeing a thread lately that talked about that brand not having an adequate power supply. So when it gets hit with a heavy screen change it dims a bit but thats only what ive read. I think ill stick with my WG's and repair\tube swap them when necessary.
 
As far as the brightness issue I remember seeing a thread lately that talked about that brand not having an adequate power supply. So when it gets hit with a heavy screen change it dims a bit but thats only what ive read. I think ill stick with my WG's and repair\tube swap them when necessary.

The power supply on the Wei-ya chassis cant handle full screen whites for starters. When the game asks the chassis to do so the b+ falls and the screen blooms. Poor power regulation is to blame. This some times happens during screen transitions as well.

Theres nothing that can be done about it AFAIK.
 
Despite the fact that the monitor is working ok now, it's true to say that the brightness issue is still there to some extent. Was tempted to buy another Wei-Ya monitor to have as a backup, but might hold out for a different brand instead on your advice. The only problem is that Wells Gardner don't manufacture new CRT monitors and chassis anymore.

Came across this on eBay. Does anyone have any info on Pentranic chassis?

http://cgi.ebay.co.uk/CRT-Part-Pent...eo_Games_Coin_Operated_MJ&hash=item56321a216d

Are Pentranic a good brand? Is this model 24kHz or 31kHz (medium or high res)? Any known problems? Would you recommend them? If so, it might be a better option for me.

Thanks.
 
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As far as the chassis working with a larger monitor than what it spec'ed out as...it worked out ok?

I contacted 8liners/victor about purchasing a Wei-Ya chassis for my 27" crt tube, and he replied that the chassis works great with a 25" tube, but he never tried it on a 27"...I was a little confused by that because his page said up to a 27" monitor.

So before I blow $125, I wanted to ask...because I don't want to throw a 25" chassis on a 27" tube and it not work.
 
If I were you, I wouldn't buy Wei-Ya at all. I had time to mess around with the chassis and can honestly say:

(1) The fact that it can't handle full-screen whites is soul destroying. You can adjust the brightness to suit one game (say Phoenix, black background etc), and then jump into another game such as 1942, and the background appears too dark for that game, and you end up re-adjusting it each time to suit each game because it can't maintain a constant brightness - very very annoying.

(2) The colour pallete goes all weird depending on what colour dominates the screen at any one time. Neutral colours such as greys, blacks and whites will start to appear blue, red, or green. Even if you compensate by manually adjusting the RGB gains, when the background colour changes again, you end up with the same issue, and resort to manually adjusting the RGB gains again to compensate. Finally you realise that no matter what you do, it will always fluctuate depending on the dominant screen colour. It's hard to explain, but this is very annoying, and very obvious to the eye. I'm not talking about subtle colour changes here, this is a very obvious colour change, so it's hard to ignore this problem.

(3) The Chungwa tube that shipped with the 2620HR model I ordered is only good for glass recycling. There's very bad 'bloom' on the screen, which gives a softness to the whole picture. I had to dial down nearly all the RGB gains just to avoid the whole screen looking out of focus. This results in the picture looking a bit lifeless. At first I had no idea that it was the tube - I just assumed that the chassis was the problem. But then I swapped the Chungwa tube for an Orion tube that came with an older Hantarex monitor, and the difference in clarity was unbelievable. Chungwa = rubbish, avoid.

Hope this advise is useful to you or anyone else out there thinking about buying the 2620HR.

One last final note - I am not casting down all Wei-Ya products. I have read articles where individuals have purchased Wei-Ya monitors from Billabs etc and were extreemly happy with the results, so I'm sure that they do have worthwhile products also. My experience with Wei-Ya is purely with the 15.75kHz standard CGA monitor and chassis that they offer, and I would honestly not recommend this to anyone.

Hope this helps !
 
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