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JNX Big Red Adapter JAMMA to MVS + Double Dragon PCB

NerdyBros

NerdyBros

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Orange County, California, USA
Hi!

I finally got my first MVS cabinet (MVS-4-25 rev.3). I'm over the moon, but it is a new world for me as my experience has only been with a consolized MVS and SUPERGUNs. One of the reasons I went with the Big Red was so I could run my horizontal PCBs in the cab with the JNX adapter. I've tried Robocop, Willow, and Final Fight. They all seem to run OK. However, Double Dragon audio is just hissing, and muffled. It runs perfectly on my SUPERGUN + CRT. I did notice on my SUPERGUN it seems to run well at about 4.5V, the lowest I can go on the MVS cab is around 4.6V. Not sure if that could be causing it, but between the picture and audio, it does feel like over voltage, even though I brought it below 5V. Cranking it higher seems to make it worse.

I know the speakers need to be in series for the adapter to work correctly, as far as I can tell by looking at the speaker wires, they match the wiring diagram, but then again, I'm no expert. Any clues? Could it be the speaker wiring but it hasn't manifested on the other boards? My only concern here is if I'm damaging the amps on the PCBs. Anyone tried a Double Dragon PCB on a MVS cab with the JNX adapter?

edit: Empire City also doesn't work, but that board has always been finicky (but it does run on my SUPERGUN).
 

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Ordered! Dumb question, I never had that problem with a SUPERGUN, is that because it provides the -5V for the boards that need it. Do the boards that don’t just “ignore” it? How do I know when a board needs the -5V? Sorry, I know I should know this when bringing cabs and PCBs home :)
 
You’re right… found this on the Aussie Arcade forum, “Usually the lack of sound on a DD board is due to missing -5volts”

Thank you so much!!!
 
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I’m no expert but I had the sound issue on my Cps2 board and then researched and found that the MVS had no -5v. The 4 slot doesn’t need it but most Jamma does I believe. I’m learning like you and don’t completely understand it yet. The Big Red adapter instructions show the spot you plug the negatron into. Happy I could help.
 
Thanks again! Got the negatron and now it works (except for the part where I had it the wrong way and I smelled something burning).

Follow-up question. Should I unplug it when using boards that don’t require -5V? Is there any harm in leaving it plugged on the adapter?
 
I honestly don’t know. This is as far as my knowledge goes. Maybe someone with more knowledge will chime in on this thread.
 
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