I have the Flash Baseball schematics for sale ($30USD includes postage
to US, Canadians have HST/PST tax to be added depending on their
province, International costs a bit more...), but I too am missing the
Ball Detect schematics. I have the large main one, amp, bat control, and
game over as well as the troubleshooting info on those and the parts
manual with 1970 prices.
I did sketch on the large schematic the beginning of the PC554-912
schematics at some time in the past, enough to give you a clue as to how
it works. The main suspect on these old PCBs is always the electrolytic
capacitors first (replace them if original!) and go from there.
John :-#)#
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(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9