________________________________
From: Tony Duell <ard at p850ug1.demon.co.uk
To: cctalk at
classiccmp.org
Sent: Wednesday, May 29, 2013 1:33 PM
Subject: Re: Power supply for HP9845B/C option 200
Hi all,=0A=
=0A=
I'm looking for a power supply for an HP9845C option 200.=0A=
=0A=
I was fortunate to acquire an HP9845C.=A0 I am in the process of moving, so=
Very nice!
? I haven't had a chance to examine it
fully.=A0 I did open up the base, and=
? it has the option 200 CPU set.=A0 It looks pretty clean inside, although t=
he power supply is missing.=0A=
Why would anyone remocve that PSU?
=0A=
I do have a couple of working HP9845B's, but these use the hybrid processor=
, and my understanding is that the option 200 machines used a beefier suppl=
y.=0A=
Yes, I beleive so. Ir's certainly different, although from what I can
tell thje normal PSU and hte Opt 200 PSU give out the same votlages.
=0A=
Does anyone know if the regular 9845B supply will work in an option 200 mac=
hine?=0A=
I think it's marginal. It might work, but not if you have the machine
'stuffed' with RAM and periperhals. And it may not work anyway.
=0A=
The schematics are pretty complicated.=A0 I'm wondering if the power supply=
Don't I know it.... 5 PCBs, 4 chopper transistors (a pair of push-pull
circits), a seaprate startup supply, 17 ICs, etc.
? has any special qualities that would prevent my
putting together a switche=
r to supply the needed voltages, via an adapter.=0A=
I see no reason why that wouldn;'t work. AFAIK all the machine needs are
the right supply voltages.
=0A=
If I can't find a supply, I may try to "downgrade" the unit to a hybrid
pro=
cessor, by swapping out the CPU from a 9845B, with a replacement ROM board =
loaded with the 9845C image; or, swap the monitor and keyboard over to a 98=
45B, and add the 9845C ROM image.=A0 Can I expect either or both of those o=
ptions would work?=0A=
AFAIK both will work (the only real differnece in the hardware is the ROM
set with the video routines, I don't think it's even the entire set of
ROMs).
But the Opt 200 prorcessor is nice, so it would eb worth trying to sort
out a PSU for it.
-tony
Hi Tony,
Thanks!? That's useful and encouraging? information.?? I would love to get a 45C up
and running one way or another.? As I mentioned, it may be a little while before I have my
lab back up and running.? Once I get into it, I plan to make extensive use of your amazing
schematics and Angsar Kueckes' similarlyamazing