Those pesky Dalsemi RTCs... (was: Re: Looking 4)

From: Ethan Dicks <>
Date: Sat Jan 4 13:53:00 2003

--- Philip Pemberton <> wrote:
> Well, I've just been putting Google through its paces once more and
> I've found a few "Pull the battery to bits and do this" style tricks for
> the Dallas Semiconductor RTCs. Have fun :-)
> - this is aimed at the
> Mostek 48x02 (48Z02, 48T02) chips, but the same sort of thing can be done
> to a Dalsemi chip.

I've already done this sort of thing with a 48T02... I whittled away the
epoxy at the nose of the chip, and exposed the battery leads. They were
easy to break, separating the battery from the chip. Then I soldered on
a 9V battery lead to the lower stubs of the connection, tacked the wires
down to the front of the battery compartment as a strain relief, and put
a lithium coin cell in a bag to insulate it in the SPARC case.

What I did with the DS1287 was similar, but since I did not know where
the battery was, I began by assuming I was going to sacrifice one to
learn how they are put together. It seems that unlike the 48T02 and
friends, which has 4 points of contact from the top and the bottom,
the DS1287 has IC pins that go down into the motherboard and up, into
the epoxy. One of the pins is the negative battery lead. I found
that one first by scraping the epoxy off. It was a simple matter to
expose the battery top and peel back the steel lead tacked to the
battery and unsolder it from the pin. The positive lead proved to be
more elusive. I never did locate it. Instead, not being aware that
the insides of a battery were hideously toxic, I _did_ cut it open,
wash out the chemicals and remove all but the outer shell from the
epoxy. I then abraded the rim of the former battery, fluxed the
bejeezus out of it and soldered a 9V battery lead to it and used the
lithium cell from my 48T02 mod (having already received and installed
geniune replacements for it from Mouser).

If my digital camera (Apple QT150) had the close-up lens, I'd take
pictures, but since it has about a 2' minimum distance and it's
a 640x480 image with high compression, the pictures would be of
limited use.

So now, I guess, I can consider further destructive testing once I
get the DS12887 installed.


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Received on Sat Jan 04 2003 - 13:53:00 GMT

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