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Display issues with 138 in 1 JAMMA PCB


Nedmond

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Hi,

Im having issues getting a video converter to properly display, the image appears ghosted. Ive tried both the RCA and S-Video outputs, 2 different converters, different PCBs, and different VGA cables (my mate bought the same gear I did), i believe its probably just a compatibility problem, if you have this PCB and output to a CRT TV, can you please tell me what video convertor you are using? There are also 2 DIP switches next to the trackball input, I dont know they playing with those would help.

Cheers,

Ned

 

IMAG0244.thumb.jpg.1084c0a29053c46238b5fedf689ec5e6.jpgIMAG0245.thumb.jpg.703f9a9175255241f232d4d204c46107.jpgIMAG0243.thumb.jpg.c39a2cf5bed028c7aaa6ae220e80a76b.jpg

 

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Cloudnt find anything like clamp settings or even geometry. I looked in the PCB, converter, and TV menus. I have been talking to diyarcade and they said I didn't need a converter so I plugged a monitor in directly and it worked for that at least so I could finish wiring and testing. I was also told that if I want cga I have to use the video wire in the Jamma harness, I don't know how to wire that directly so maybe I need a converter with the RGBS pins as input. I've ordered a cheap vga to svideo/RCA cable so will see if that will work. Probably won't but it was $5.60 delivered so I'll give it a go. I will attach a pic of the issueIMAG0248.thumb.jpg.fddb213ee0feccc09777a508ee008732.jpg

 

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Does anyone know how to make the CGA video wires from the JAMMA harness (ie red, green, blue, ground, and sync) go to the TV? I'd imagine it would require a converter but can't seem to find anything CGA to CGA.

 

Maybe I just need to try a different VGA to CGA converter? There must be one that works with the 138 in 1 and I can't be the first guy who wants to hook it up to an old school TV for the authentic scanlines look...

 

any suggestions greatly appreciated!

 

cheers,

 

Ned

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Does anyone know how to make the CGA video wires from the JAMMA harness (ie red, green, blue, ground, and sync) go to the TV? I'd imagine it would require a converter but can't seem to find anything CGA to CGA.

 

Maybe I just need to try a different VGA to CGA converter? There must be one that works with the 138 in 1 and I can't be the first guy who wants to hook it up to an old school TV for the authentic scanlines look...

 

any suggestions greatly appreciated!

 

cheers,

 

Ned

 

What about putting a scanlines converter on the vga?

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Does anyone know how to make the CGA video wires from the JAMMA harness (ie red, green, blue, ground, and sync) go to the TV? I'd imagine it would require a converter but can't seem to find anything CGA to CGA.

 

Maybe I just need to try a different VGA to CGA converter? There must be one that works with the 138 in 1 and I can't be the first guy who wants to hook it up to an old school TV for the authentic scanlines look...

 

any suggestions greatly appreciated!

 

cheers,

 

Ned

 

What inputs does the TV have? If it has a Scart RGB input you can wire from RGBS on JAMMA to Scart without a converter just a custom cable, although you may want some resisors in line with the colours if it's too bright. If you have component inputs a Scart RGB to component adaptor could be used, again possibly needing resistors in line with the colours to control the brightness. If you have to use composite input WeiYa make a RGBS to composite converter but it will have the worst video quality of any of the options I've mentioned.

 

If you convert VGA to CGA you will be stuck with an interlaced image that will never have the genuine scanline look you're after, except if you can output a lowres signal on VGA using the 138 in 1 - if this is the case you don't need a converter though just a wiring adaptor that can combine the H+V syncs into composite.

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That's swear a LOT! not slot... Still sad, I based my whole cabinet design on being able to use CRTs with s-video for the PCB, and also be able to use PS2's with light guns and system link for proper 2 players 2 screens time crisis 2 & 3. Would have been awesome :(

 

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One of these should work:

http://www.ebay.com.au/itm/Weiya-CV-04-RGBS-RGB-CGA-arcade-jamma-game-to-TV-composite-video-converter-MAME-/260868532793

 

While composite will work the quality of the picture will not be great. Maybe finding a TV better suited for both s-video from PS2 (or component if it works with light guns, I'm not sure) and RGBS (through Scart or converting Scart RGB to component) from JAMMA is a better solution.

Edited by dee2eR
typo
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Thanks, I was looking at those and wondering if it would work. My 1st arcade machine had no issues with a normal video converter so I tried RCA and S-video and you are right, the RCA was terrible.

Finding another TV will be hard but will look around. It needs to be a 4:3 aspect ratio and be 60hz as the light guns won't work with 100hz (I tried it on a Loewe 78cm wide screen I had once). I don't know if when scart came out Tvs hadn't all moved beyond 60hz... I hope not. I could also sell the 138 in one and try and find a board that works like the 68 in 1...

Thanks for your suggestion, if by some miracle I find a solution I will post it here.

Cheers,

Ned

 

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I'm a bit closer to a solution and have 2 irons in the fire:

 

1 - I've ordered one of these which may work:

https://www.aliexpress.com/item/Arcade-RGB-CGA-to-TV-and-Video-Composite-converting-board-game-accessory-for-arcade-game-machine/502847877.html?spm=a2g0s.9042311.0.0.GMuqq0

It does RGB to S-Video so could be acceptable if it solves the display issue

 

2 - I found a guy on gumtree who has modded a 68cm 4:3 ratio 50/60hz Sony TV with RGB and has installed a scart connecter in the back of it. Since I don't have the skills to do this myself I bought this TV as a backup plan. It was built for the purpose I want it for and was $150 so I figured it wasn't too much compared to what I've already spent on it. I'm looking to build a circuit to convert the wires from the jamma harness to the scart connection in the back of the TV. I have no idea what I'm doing with resistors etc so I'm relying on the diagram I found on Google being correct. The alternative is to buy a circuit from the UK, with shipping it's abit over $100. I think I can build it for around $20ish but might mess something up. The mate I've got who is also building up a machine will buy the converter mentioned previously if it works and I can get this to work which is pretty handy or I might decide I couldn't be bothered with RGB and sell the modded TV.

 

So that's where it's at, stay tuned for the results which should be out in the next few weeks.

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The video converter I got from Ali express worked, although it seems to cut off about 1cm all around the screen, because it's a CRT there are no adjustments in the function menu of the TV. The colours were ok after some adjustment of the RGB pots, it's acceptable, but now I have the RGB modded TV, I'm going to continue working with that and make my own circuit board with a female scart plug, 500 ohm pots on the RGB wires and the other resistors recommended in the diagram towards the end of this page:

http://www.geocities.ws/podernixie/htpc/cables-en.html

 

I think I need 1 watt rated resistors for the sync and power but will go for 2 watts to be safe. The RGB wires have very low current and voltage and 0.25 watt is all I should need but will go 0.5 watts as the only disadvantage I see to over engineering these is size and slightly higher cost.

 

The modded TV will arrive in about a month.

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