JAMMA adapters and sync

modessitt

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I guess this would be a monitor question:

When building JAMMA adapters, I want to make sure that my bench monitor is set up so that I can run different syncs to it without having to get up and physically move the plug. I figure that since the JAMMA connector has just one composite sync, I can run a wire to both the positive and negative side, and just put a switch in to select between positive and negative, right? I just ran into this when I tested a 1943 (which has composite negative sync) and then used my JAMMA-to-Sega System 8 adapter for Choplifter, and had to switch it to positive sync on the monitor.


Also, I've been wondering how JAMMA adapters deal with games that have separate synce, instead of composite sync? My K7000 test monitor usually only wants the composite sync on the horizontal pin, so I figure I can just connect the horizontal to the JAMMA sync output, but what about if I use it with a G07 or something? Will it still sync?


Anybody have any thoughts?
 
Well, just to keep things interesting around here, I just put a 2nd Choplifter board on the bench, and it will only sync with negative sync.

So, I have two Choplifter boards, and they each sync with a different sync. Looking at them, the only difference I see is one board has a chip with a cap connecting two legs, and the other board doesn't. I'm going to go disconnect one leg to see if it goes back to negative sync. Anyone know which sync is factory? Dunno if someone made a mod to one to match a specific monitor....
 
Okay, well lifting that cap off on one side didn't change the sync, so I have two Choplifter boards, one works with positive sync and the other works with negative sync. The manual states composite negative sync, so not sure what's up there. The sync selector switch I hooked up is working fine though.

Guess I'll go ask in the regular help section...
 
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