reverse-engineering power

From: jpero_at_mail.cgo.wave.ca <(jpero_at_mail.cgo.wave.ca)>
Date: Sun May 17 16:00:16 1998

Doug and everyone...

> > > I'm reading around 3.2V, which would make sense for a laptop.
> >
> > Unless you know it's a 3.3V logic family, then I would suspect that it
> > too low. What is the complete number on the chip you're testing?
>
> Most newer laptops use lower-voltage logic to conserve battery power.
> This one was designed to demo a couple of highly-integrated chips, so the
> only 74-series chips are some 74AC244 and 74ACT244 buffers. I tested one
> of the "AC" chips.
>
> -- Doug

3.2V? That's seems not right for that ttl cmos family. Should be
~5V +/-5% Keep cranking that power source up bit by bit slowly and
monitor the voltage rise or no change?

Nearly ALL battery portables use a power supply/charger/power
management module and is supposed to be VERY toleranent of WIDE
changes in current and voltage ranges between min (battery minium
voltage at near discharge end) and max voltage that happens during
charging process. These modules vary in all sizes and some notebooks
has it all on same board with everything else. Tiniest I have seen
so far is in compaq LTE 386s/20 (about 1" x .75" by 2") and largest
one I have so far seen is in Epson NB SL/25 notebook.
Your pototype looked nearly complete to go into a notebook at get go.
So that's means it should have a functioning PSU module part.
And nearly all PSU modules use switching technologies.

3.3V based portables started to appear after Intel and AMD introduced
their 3.3v chips and chipsets became common after '91 or so.
That real appearance takes place about a year after this and totally
converted over to all 3.3V logic well after dx4 portables became
common.

I have a sharp eye for someting amiss. Did you have any few
small chips that is stuck with some kind of sticker at all even in
socket? This is typical for bios And can you find a CPU somewhere?
I think this is 386sx class notebook maybe based on amd or SLC type.

Did you have that 32pin SOJ socket empty? That is might be the
socket for that bios oh, what a big bummer!

And you do have a heard drive made by Areal, long since dead HD
maker.

Jason D.
email: jpero_at_cgo.wave.ca
Pero, Jason D.
Received on Sun May 17 1998 - 16:00:16 BST