JAMMA wiring

So, I was rewiring everything JAMMA (oh, the joy) to use a Gallag JAMMA adapter and get rid of the old dodgy wiring.

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During that process I found out that the adapter I had was incorrect for the video part. Sync and Ground were inverted and I spent almost a night trying to figure out what was wrong until I triple checked the original wiring and noticed that it didn’t make any sense, especially when fitting another unknown game would produce a good image.

I was about to jump out of joy but I noticed that:

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Hang on a second, artefacts and missing lines in the sprites, aaaaargh.

So, I’m not sure if the PCB didn’t like the Queensland summer or if I fried something when messing around with that sync issue, but there you are, I had a buggered PCB.

This is when I had to reconsider the entire “original” cab project because I ended up with a bad PCB that I couldn’t fix.

I desoldered the 2 RAM chips and could determine which one was causing the issue but swapping them would still work so they are both OK. I suspect a bad track of another bad chip somewhere but I had already spent way too much time on that.

On top of that, the PCB + JAMMA adapter didn’t fit in the cab and I would have had to create another adapter to get a flexible connection between the PCB and the JAMMA connector.

So I decided to buy a 412-in-1, and call it a day… But wait, there’s more in the next episode!

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