The problem with "non-keyed" arcade jamma pcbs...

[PC Engine Fan X!]

In the arcade pcb hobby, I've come across some non-keyed jamma pcbs whereas my candy cab has a keyed 56-pin jamma interface as it is. I don't want to remove the key from within the 56-pin jamma interface and accidentally plug in the jamma connector backwards thus frying a very expensive & valuable arcade pcb in the process -- what to do with playing a non-keyed jamma pcb with a "keyed" jamma interface on said candy cab?

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I've come across more than my fair share of acquiring/buying "non-keyed" jamma pcbs (especially the bootleg/knock-off pcbs that pop up for sale on the secondary arcade pcb hobbyists market nowadays) -- it comes with delving into the territory of arcade pcb gaming/collecting hobby head-on as usual.
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The surprising answer to that particularly pressing question/quandary is: Buy a "keyed" voltmeter jamma pcb like this one here: https://www.ebay.com/itm/115425456464?_ ... GiZg&pfm=1

This "non keyed" jamma pcb issue would equally apply to a supergun setup (assuming that it has a "keyed" jamma interface, of course -- if it doesn't, then playing both "keyed" & "non-keyed" arcade pcbs really isn't that big of a deal).

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The Spain produced TourVision arcade pcb that was sold and distributed in both Spain and France back in the early 1990s (basically an arcade pcb endowed with a PC Engine with four Hu-Card slots & running on a "countdown timer" setup -- similar to United Amusements' NEC TurboGrafx-16 Jamma pcb released in the USA back in late 1989/early 1990 with it "countdown timer" setup as well with it's ability to play both Japanese Hu-Cards & American Turbo Chip carts without the need for a Hu-Card convertor anyways -- this particular jamma pcb uses a stock PC Engine in conjunction with "countdown timer" pcb and is regulated to being a single player stint at best) is quite notorious in that it isn't properly "keyed" to begin with, hence it requires a "keyed" voltmeter jamma pcb if used with a "keyed" jamma 56-pin interface indeed. So be it.
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PC Engine Fan X! ^_~

[Sumez]

I guess you answered your own question??

I have one of those cheap voltmeter JAMMA adapters in use all the time, myself. It pulls extra duty with some extra things I soldered onto it, like a "negatron" for -5v output for the few PCBs that need it, as well as a passive video splitter.