help with zaxxon board to jamma

[redfivexw]

hi everyone,
i have an original zaxxon board that i bought as tested and working from a reputable source.  I made a jamma adapter last night and double checked all the connections, pinouts, etc and am sure everything is hooked up the way it is supposed to be, but when i plug it in, all i get is green static.  The only connection i am not sure on the board is video ground, the zaxxon board does not have a video ground pinout, but jamma does.  I am not sure what is wrong, anyone have any ideas?

[Dav]

You need to wire the V Ground to   ground or the monitor won't work right.  Usually what I see though when  I forget to wire it, is the picture is washed out and wavy.  Can you hear it coin up?  Did you wire the test switch in your cab?  If so then try flipping it the other way.  iirc test is video freeze and it won't boot.

If you still can't get it  I have  pcb based zaxxon adapters for $25.   That includes an inverter for the sync and jumpers so it will run Congo Bongo etc as well.

[redfivexw]

I did not get anything, the screen was just fuzz and the picture kept jumping.  Could you explain the grounding better?  As i said before, i do not see a pinout on the zaxxon board for video ground, so where do i wire the video ground from the jamma edge card to?  If i cannot figure it out i will definitely take a jamma adapter from you!  thanks for your help.

[Dav]

On the jamma finger connector run the video grd to the main ground.  The monitor has to have a grd signal so it can reference the video signals it's getting.  Some/All? of the zaxxon boards have a switch to invert the video sync, there's info on location in the pinout.  That might help the rolling, if the ground doesn't.  Congo Bongo I know doesn't have the switch, which is why I add an inverter to my boards.

But if you're not getting any sounds, none of that stuff will help you.  You've got something else going on.  Could still be the test switch turned on keeping it from booting.

I take paypal, if it's not from a credit card.

[redfivexw]

i cannot tell anything about sound because i did not hook up the sound yet, it said on the pinout to connect sound to another connector on the board, not on the edge connector, i was going to hook that up after i got everything else working.  I know the board was working before i got it, i got it from quarterarcade.com, and they had a photo of it hooked up and working.  so you want me to run a wire from the video ground to the main ground on the jamma fingerboard itself?  i will try that, give me your paypal address in case i need to buy your adapter...

[Dav]

I've bought many boards from quarterarcade w/o any problems, so it probably is your adapter.   But it wouldn't hurt to reseat the cpu and roms and ribbon cables.

The sound can be pulled from the edge connector, should be 7 & H. 

I pm'ed my email address.  There's no hurry.  I just got 8 zaxxon adapters with my last PCB order so I have plenty.