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pearce_jj
December 7th, 2011, 12:55 PM
Evening all, I'm working on an old fruit machine (MC68k CPU with 16k static RAM). It uses a classic 2.4v 110mAh NiCd soldered on the CPU board. Machine won't run enough hours a week to keep it charged.

It will work without it, but wouldn't play properly as it won't have any payout stats.

Hence looking for options to change the NiCd battery for something else. I'm not sure what the battery powers, if it's just the two static RAM chips that would be only about 4uA. CPU is MC68EC000FN8, which I don't think is a static variety.

pearce_jj
December 7th, 2011, 01:49 PM
How about a CR2032 conversion?

http://www.electronics-related.com/usenet/design/show/98462-1.php

Is the exact voltage applied to static RAM chips important?

Chuck(G)
December 7th, 2011, 02:16 PM
How about a CR2032 conversion?

http://www.electronics-related.com/usenet/design/show/98462-1.php

Is the exact voltage applied to static RAM chips important?

What are the static RAMs? A datasheet might tell you what they need to stay alive.

pearce_jj
December 8th, 2011, 12:49 AM
Hi Chuck, the chips are GoldStar GM76C88AL-12 (http://vintage-blog.peacon.co.uk/downloads/manuals/goldstar/gm76c88al-12.pdf) (2 of), so if these are the only draw on the battery then power requirements look almost negligable (pg.9 states 2 - 5.5V, typical 3V 1uA).

I'm thinking solder fly leads and keyed connector onto the board, and wire to remote mounted supply consisting of 3x alkaline AA batteries in a holder with a diode inline on positive side to block the charge voltage when the machine is on?