PCB Reproduction: Space Harrier/Outrun Deluxe Motor Drive

I thought I’d plug the PCB we’ve been working on over at UKVAC.

UKVAC link

IMG_5348
The PCB in all its glory

It’s an open-source Circuit Maker project where we took the hard-to-find motor drive PCB for Outrun and Space Harrier Deluxe and made our own.

Circuit Maker link

Engineering-wise, we had the original schematics to follow and, fortunately, we also had access to a PCB to work out the unreadable bits.

A dump of the two 153 PALs was also obtained (thanks Retroclinic).

A bit of an art project really, as we tried to match the original functionality and routing as closely as possible. Where components are obsolete, it’s dual-pinned (e.g. those are 22V10 GALs I’ve translated the 153 code to).

An interesting PCB. It drives 1 or 2 DC motors from an 80V ac mains supply by synchronising to the mains and enabling the triacs at the appropriate points of the positive or negative mains-cycle. All control is via 74LS logic and the PALs – the game PCB simply send a pair of 4-bit speed commands (where 0x8 is stationary).

IMG_2302

IMG_2305
Positive speed (top) and Negative speed  (bottom) – yellow is mains (sort-of), blue is triac/motor current.

So far it seems to work well in the cabinet it was tested in (and lots of bench testing was done by me beforehand as I haven’t got a cabinet), so a couple more prototype tests and it should be good to do.

I’ll not go to too much technical detail here as it’s all on UKVAC (log-in to see the Arcade Homebrew page  where we try to work it all out, including the triac circuit and even a video), but if you know anyone who needs a board then follow the link above.

Note that it’s cheap as it’s non-profit and non-commercial, so no-warranty is offered.

I’m (JB) also happy to try and help with questions on fixing old motor drive PCBs.

 

Not Phil

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