NBA JAM TE "NO SOUND IRQ" with Jamma to Neo Adapter

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NBA JAM TE "NO SOUND IRQ" with Jamma to Neo Adapter

Hello.

I've seen other posts about this issue, but was hoping to find some specific help.

I am running Jamma games on my Neo Geo 4-slot ver 3 through a Jamma-to-MVS adapter with negatron (for the -5 volt stuff). All my Jamma games run sound fine, except for Jam.

I have the sound board and the ribbon cable seems to be hooked up correctly. Is there another wire or cable that I need? I get no real ding, and when I run sound diagnostics, I get the CANNOT DETECT SOUNDBOARD IRQ.

Any help would be appreciated. Thank you. -MGK
 
If I don't nail this, Mecha will.

I think the sound board is not getting powered, check for the +5 from the MVS adapter.

There is another harness to steal power from the main board and another harness with a pot to adjust volume.

If the ribbon is all you have, you will need the other two.
Good luck and post back with your results!
 
If I don't nail this, Mecha will.

I think the sound board is not getting powered, check for the +5 from the MVS adapter.

There is another harness to steal power from the main board and another harness with a pot to adjust volume.

If the ribbon is all you have, you will need the other two.
Good luck and post back with your results!

Which two ribbons would you mean? Any place that I could find a picture for better understanding? Thanks btw.
 
do you get the ding sound when the game turns on? if not, then the sound board probably isn't getting power. NBA Jam doesn't use -5 anyway, but criss-crossing Neo Geo JAMMA harnesses with non-Neo games isn't a good idea.

the use of adapters will swallow up power too. just because I didn't know anything about Neo Geos last year I tried plugging a kit Neo into an MVS cabinet and the sound was all sorts of screwed up :)

the sound board has a power harness (if original, it'll be a series of grey/blue/purple wires) and a ribbon cable for interfacing the data calls between the CPU board and sound board. if you're missing this ribbon cable then that's the problem, as the error message is actually saying there's no communication between the two boards.

if you do have the ribbon cable intact, if you look closely at both boards there will be numeric labels on the ribbon cable headers. they'll say 1/2 on one side and 19/20 on the other. you must align the red stripe of the ribbon cable on the pin 1/2 sides of both boards. you won't damage anything plugging the cable in backwards on either side, but the data won't work unless you have it aligned correctly.

you could just have problems circumventing and hacking around that Neo Geo harness too though.
 
it's one big end on the CPU board side and a couple plugs on the sound board side, for sure. volume pot is a huge difference maker if you don't have one though. :p

won't tie to the IRQ issue though in the slighest. you just won't hear anything.
 
Okay, guys...ridiculous amount of help.

I don't have either power wire or the volume wire.

I found the power wire on ebay. Still looking for the volume pot one!
 
The volume pot is also on ebay. Or you can get it direct from me a lil cheaper than ebay.
 

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Just throwing this out there. 99% of the time, if you have all the cables and still have the 'No IRQ' error, it means you have a problem with the ribbon cable of some kind.
 
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