*facepalm* Galaxian AC Conversion Screwup

Peale

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I should have looked at the conversion docs more closely. I was stupid, and swapped the +5VDC and +12VDC lines. Fried something, but I'm not sure what. What should I look at, first?
 
Nothing is getting hot any more. When I first realized what I did a lot of the chips were hot, but now that I've switched things back, things get warm, but that's it.
 
If you put 12v through the 5v line you might want to start looking for another board. How long did you have it powered up like that?
 
Longer than I'd like. I eventually heard a *pop*. I can't SEE anything cooked, but that doesn't mean anything.
 
Galaxian boards are plentiful and if you put 12V on the 5V line and it got to all of the ttl chips they may have been damaged but not enough to fail immediately. The board will not be reliable. And chips will continue to fail over time until all of the marginal ones get replaced. I've been there on a few boards sent to me for repair. If it is a rare classic it's worth the trouble but for Galaxian you are better off getting another working board or spending your time repairing a non-working board that did not have the misapplied voltage.

Don't feel too badly about it - we've all done stuff like this. I've let the magic smoke out of more than a few parts :).

Bill
 
If you put 12V through the 5V line then it is likely you have killed every single chip on the board. The 5v rail goes virtually everywhere, most TTLs, RAM and ROMs will die at 6V and some Z80s are ok up to 6.5. Once you get beyond 7v everything pretty much dies. The pop you heard is either a chip blowing out on the underside, or something shorted out internally and connected the 12V to ground via a PCB track. The PSU will step up to the challenge and provide an amp on the 12V line which will vapourise whatever track is in the way. Chances of it being a complete and total wreck are about 99% at this stage.
 
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