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Jamma passtrough with VGA out

PascalP

PascalP

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How feasible would it be to design a Jamma pass-trough with VGA output?

The RGB lines would have 220ohms before going to the VGA.

I want to use something like this in both my NNC and Cyberlead cab to bypass the crappy Namco adapter as it degrades video quality.
Currently I do have a Jamma pass-through with some wires and resistors soldered to it to a VGA, but I don't think this is a very clean solution :)

No idea what is involved in designing a simple PCB like this and how much production would cost for just a few? ?(
 
you can use eaglecad, chinese fabs will build small bactches, min 10, shouldn't cost you more than a 100$
 
This is something I could look into.
I got a small order of bare jamma adaptor boards made, they came out at 4 UKP each.

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I would have thought that the board would be a little more complex due to the vias + holethru's needed to mount a vga
connector on one side. The components are likely another 1.50 UKP or so.
 
That would be awesome if you could design a pcb with added VGA and resistors.
Could be easy passthrough instead of the solderpads if that makes it a bit more compact ;)
 
So just to confirm.. what you've wired up is still outputting standard jamma video at 15Khz?
Would it even work for tri-sync stuff / 31Khz modes... :huh:

I've not been inside a Cyberlead cab (lucky you, btw!) but from what you are saying I'm guessing the usual monitor cable is fitted with a VGA plug then? Might need some photos to see what you have working there already :)
 
Yup, just standard 15k Jamma, cyberlead uses a Nanao MS9, just wired via VGA.
Same works for the trisync in my NNC.

I could also think of another use case for this adapter, connect it between any Jamma harness and run the VGA to an OSSC for streaming or something.

So basically all signals 100% passthrough + splice the RGB lines and add 220ohm for VGA levels, + splice sync and ground to vga
 
Yeah I don't think that would affect the normal jamma video output - it would effectively be doing the same kind of thing that I'm doing with my linkup loom between 2 cabinets.. (and I don't have any resistors there).

Thinking about it, wouldn't resistors just dim the image down?

What I have found is a ground loop is caused when I use my pi box (it has a JPAC) and using the link loom. Could be due to the 2nd switcher in the slave cab though - I've not got round to disabling it during testing yet.
 
Yes the resistors dim the image, otherwise it is too bright.

I’ve already made a simple splitter/adapter by soldering some wires to a fingerboard.
Without the resistors the image was too bright.
 
@PascalP short question, because i would need something like this as well, at least till i get my has, which signals need the 220ohm resistors, the sync as well?

(sorry propably a dumb question :/ )
 
Just use the resistors on the RGB signals, leave the sync alone :)

Btw, would be even better to use for example 1k pots rather than the fixed 220ohm resistors.
 
I'm looking to build a similar pass through PCB with some simple pin swapping.

I'm curious does anyone know what the official JAMMA spec states for dimensions on the edge connector (pin pad length, width, spacing, PCB thicknes, key width, etc.)
I'm also curious if there's a good JAMMA female connector that people recommend using for the game-side of the adapter?
 
twistedsymphony said:
I'm looking to build a similar pass through PCB with some simple pin swapping.

I'm curious does anyone know what the official JAMMA spec states for dimensions on the edge connector (pin pad length, width, spacing, PCB thicknes, key width, etc.)
I'm also curious if there's a good JAMMA female connector that people recommend using for the game-side of the adapter?
Click to expand...
It's officially
3.96mm / 0.156" Pitch



I found this out making up my jamma adaptor boards:
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For the female end I just got a load from schenzen. They're all the same really :)

 
twistedsymphony said:
I'm looking to build a similar pass through PCB with some simple pin swapping.

I'm curious does anyone know what the official JAMMA spec states for dimensions on the edge connector (pin pad length, width, spacing, PCB thicknes, key width, etc.)
I'm also curious if there's a good JAMMA female connector that people recommend using for the game-side of the adapter?
Click to expand...
You are better off measuring edge connector on pcbs in your collection to get better understanding how they vary. The biggest issue to compensate for is the width of the pcb for the finger, if its too narrow the pcb can move within the connector and cause a short. DigiKey stocks 0.156 card edge connectors from Sullins and EDAC, not cheap. But they fit way better than anything you will buy from China, and are also gold plated too.

@Flinnster Can tell just from photos without measurements your pad layout for jamma has issues. (pad is too wide, and too long. pads on either end are too close to pcb edge)
 
brizzo said:
@Flinnster Can tell just from photos without measurements your pad layout for jamma has issues. (pad is too wide, and too long. pads on either end are too close to pcb edge)
Click to expand...
Yep, the design was OK but at manufacture the boards came out nearly 1mm less wide on the overall pcb (although I do have another purchased jamma adaptor board here that's even narrower!).
Also I have a bunch of bootlegs that have trimmed pcb connector areas anyway (from various operator mods) so I'm used to not just lazily shoving pcbs into my jamma loom without being careful & checking anyway.

If get any more manufactured I will likely shrink the individual finger / pad sizes and length - but these boards do work.
 
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