Issue with JAMMA Versus Link Cable

[VS_Lilith]

I recently purchased these link cables to connect 2 NAS cabinets together for head to head gameplay however it seems on the slave unit the monitor output is completely messed up. Sometimes its dim and it always has some sort of sync issues

MASTER VS. SLAVE



Here is what the harness looks like:



Any help or advice is appreciated.

 

[VS_Lilith]

Do you mind posting the link where you got that cable from?

https://ebay.us/m/JCV24I

 

[Zepherino]

That cable really doesn't look fit for purpose... The bare PCB on the side without the socket is also a bit risky since it's easy to install upside down and accidentally push 5V where it doesn't belong for some magic smoke action. With the boogery hot glue everywhere, I would be checking for the quality of the solder joints, assuming this cable is supposed to work at all. Usually I would see major dimming/sync issues when only one of the two linked cabs are powered on. Another thing you should check is that if the cable is actually JAMMA or CHAMMA, since there's no kick harness. There may be some differences in wiring that ends up messing with video as well.

I would probably look for a better link cable if possible. I can check to see if the one I use is still being produced, although it would be significantly more expensive than 22USD.

 

[VS_Lilith]

one of the things that confused me is the fact that both sides are wired in for +5v and +12v, is it fine for that to be connected and wired to the pcb on the slave unit or should the slave not be interfacing with power at all?

 

[VS_Lilith]

Thanks for the suggestions, I'm looking to see if I can fix these ones I got here, any advice is appreciated I'll prob take the glue off one to check connections

 

[Zepherino]

Based on the photos shown, there's a wire (pink) soldered to pin#26, which means that this is probably wired for CHAMMA. Unless your cab harnesses are also CHAMMA, this would be the first thing to correct.

Both sides being wired for 5V should be correct. You can verify the correct voltage by powering on without a game and checking with a multimeter.

 

[VS_Lilith]

Based on the photos shown, there's a wire (pink) soldered to pin#26, which means that this is probably wired for CHAMMA. Unless your cab harnesses are also CHAMMA, this would be the first thing to correct.

Both sides being wired for 5V should be correct. You can verify the correct voltage by powering on without a game and checking with a multimeter.

sounds good, and sorry if I miscommunicated, what I mean by the 5V/12V is that both connectors on the link cable have this wired to the game board, meaning both the master and slave units are powering the board, is this normal as I see other link harnesses only have power to the board thru the master passthrough and not the slave connector as well.

 

[kazuo]

I think you ideally want (or even need) to have a load on the other machine. But I am not a expert. Not sure how this harness is handling that.

Agree with others in the thread, this looks like it is wired for CHAMMA, and that fingerboard missing the JAMMA key is a bad day waiting to happen. My advice: buy another harness.

If you are like "sunk cost!", or you're just open to trying to fix it or picking up a project, I'd pull up CHAMMA and JAMMA diagrams, buy a new fingerboard with the correct JAMMA key, then re-wire. You might also want to get a CPS-2 connector/pig tail and wire that in while you're at it, it'll make things a lot easier.

The video issue that Zepherino described is probably because something something load/resistors needed... somewhere? I seem to remember this being discussed a while back, and I am pretty sure the ancient River Service link harness I have has a bunch of resistors in random places. Sorry I can't be more helpful than this.

I think Franco used to make these and sell them; you could try looking up his thread on Arcade Otaku and see if they discussed any of the nitty gritty details.

Good luck with it!

 

[Zepherino]

sounds good, and sorry if I miscommunicated, what I mean by the 5V/12V is that both connectors on the link cable have this wired to the game board, meaning both the master and slave units are powering the board, is this normal as I see other link harnesses only have power to the board thru the master passthrough and not the slave connector as well.

Yes, both sides should be powering the harness. Otherwise you're splitting video between two cabs with one power source. If you ever used a crappy passive VGA splitter before, I imagine the effect would be similar. There would be a drop in voltage and a negative effect on video quality for both displays. As Kazuo mentioned, there's likely some components in between that would also be needed in the link cable.

More knowledgeable people can chime in, since I'm more layperson than expert.

 

[VS_Lilith]

So I made the harnesses non chamma, and I'm still getting the same issues, another thread mentions how the monitors are grounded, should they both be sharing the same ground/sync wire?

 

[wigsplitta]

Here's how my VS cable is wired if it helps (glad I checked, noticed the universal ground cable is broken!)

Looks like your cable is missing pin 14, video ground.


28, 27, 14, 13, 12, 10



f, e, b, a, Z, Y, X, W, V, U, T, P, N, L

It doesn't need any voltage passing through, just the video, sync, audio and ground (plus controls)

 

[VS_Lilith]

Here's how my VS cable is wired if it helps (glad I checked, noticed the universal ground cable is broken!)

Looks like your cable is missing pin 14, video ground.


28
27
14
13
12
10



f
e
b
a
Z
Y
X
W
V
U
T
P
N
L


It doesn't need any voltage passing through, just the video, sync, audio and ground (plus controls)

Oh my god you're right... Thank you for catching that I dont know how I kept going over it! I'll fix her up friday when I'm in and report the details

 

[VS_Lilith]

Bingo, that was it! Thanks for pointing it out I really needa pay attention more!