>On the topic of frying, in the article I found about installing a >backup
>battery (mine didn't have one, but had the solder pads, so must >be the
>second edition mkI), it said to cut one lead of D1 (ie. remove >it without
>physically removing it) - any thoughts on why this is so, >and what the
>implications are? I did what it said, but am not too >happy about the
>thought of any loose current frying the board...
>IIRC, when I looked at my original fried poly, the service manual said
> >that D1 was the main protection circuit - but of course there was no >D1,
>so...??
Not that I know anything about the internals of the Poly but I would guess
that removing D1 has something to do with transferring power to the RAM chip
from adapter power to backup battery power. Cutting one lead is a nice way
to disconnect it because it's easy and it's not too hard to reconnect it if
you want. If it's a protection circuit, I can imagine it being either one
of two things. First, it could protect against reverse voltages (either
installing batteries backwards or using the wrong adapter)....but then
disconnecting it to use the backup battery would keep it from turning on at
all and anyway it wouldn't have anything to do with the backup battery. Or
second it could be a zener diode designed in some way to protect against
overvoltage. Maybe the way it's set up the backup battery would short out
with it present. Interesting...
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