You know, reproducing old hardware, especially custom one, is vital for preservation purpose and it doesn't really matter if the part taken into accout is not often seen on arcade PCBs.Perhaps it's the case of the 'SEI0050BU', a custom IC found on some Seibu PCBs like Toki, Cabal, Raiden (some hardware revisions) and few other.
The IC comes in a 600 mil SDIP40 package :
There is no official documentation or schematics/pinout about this custom IC (except for some mention in MAME source) hence for first I figured out the direction of each pin.Then, as always I do, I studied how its functions were reversed on bootleg boards with the use of simple logic gates.The resulting schematics drawn gave me the equivalent circuit that was then routed to a proper board.For a first "quick & dirty" prototype I chose simple thru-hole parts, there is no point using SMD or complex programmable logic devices if you first of all didn't validate the design :
Not the neatest and smallest layout perhaps but the prototype worked fine.Here is test on Toki and Cabal PCBs :
We now have a solution to replace faulty 'SEI0050BU' custom ICs and save more boards from uselessness.
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