Whirlwind PC to JAMMA Arcade Cabinet Interface

[darknezz19]

Have not seen this talked about much on forums. It's an open source Jamma to PC interface card. Uses a Pi Pico to handle logic and inputs. RGB amplification via THS7374 or THS7375, which apparently is better suited for Nanao monitors. RGB gains can be fine tuned via pots. Has a sync monitoring pin to cut output if sync is out of range. Also sports an audio amp circuit. The inputs are can be scripted for hot key functions.

I've ordered some PCBs and will be building one in the next month or so.

https://www.instructables.com/Whirlwind-PC-to-JAMMA-Arcade-Cabinet-Interface/

 

[darknezz19]

Got around to testing it out today. I used a THS7375 for the amp, as this will be going into an astro city with an ms9-29 soon. Worked fine on this k7000 for now which was used to test. The sync monitor works good, and no picture is outputted when the sync is out of range when booting. One thing though is I could not get the onboard passive sync stripper to work. Luckily Groovymame already supports composite sync, so just enabled that and replaced the diode with the 820ohm resistor, normally on the vertical sync line. All the inputs work through the pi, and didn't notice lag. Another thing changed was added 75ohm termination for the VGA RGB input impedance. I also put a pot on the sync output with one leg tied to ground to adjust sync voltage. This probably isn't needed, and it syncs fine without it, but voltage is like 5.6vpp without it, which is getting a bit high. Dialed it back a bit for safety. Pics are from the k7000, I'll post some ms9-29 once that's tested here in a bit. I didn't populated the circuit for the audio amp as using self powered subwoofer with active speaker output on them. Overall am happy with it so far. I wonder if the pi's inputs would work on a mister, will have to test that too. My camera didn't really do justice on the sharpness of the picture, it's sharp. The colors are there though and look good.