22 Aug
2011
22 Aug
'11
1:09 p.m.
Hi all --
Anyone have a service manual for the HP 9485A (not the B or C)? I
picked up three of these machines in fairly good physical condition just
a couple of days ago, but their operating condition leaves something to
be desired :).
I've looked in the usual places (hpmuseum.net, and hp9845.net) but I can
only find the manual for the B/C revisions. My understanding is that
the "A" version is different in some ways (not really sure what the
hardware differences are yet.)
I _believe_ the _A is quite diferent from the -B/-C. The last 2 machines
are quite similar (differing mainly in the monitor section, the video
circutiry being inside the monitor).
As I am sure you know, these machines have 2 procesosrs, originally HP
BPOC hybrid modules. One runs the user program (the 'Language Procssor
Unit'), the other handhels I/O (the 'Periperal Processor Unit'). There's
some arbitration logcic to connect these processors to the varios memory
devices.
In the -A, I beleive, the 2 processors are on one PCB, there's a separate
PCB with the arbitration logic on it. In the -B, Each processor anf it's
part of the arbirtration logic goes on a PCB (stlll 2 PCB,s but
differnetly arranged). One advantag of this is that the LPU board can be
replaced by a 'High Speed LPU Option' which is a set of 3 boards stffed
with MAD2900 chips.
Of course the backplane is differnt too.
The good news is that one of the three 9845s just required some careful
reseating of the cards and ROMs and it now appears to be working
correctly (I haven't yet tested the printer (no paper yet) and I'm
I think it'll use normal thermal fax paper.
assuming the tape drives will require a bunch of work,
assuming I ever
The tape drive mechansims are the same as those in the 9815 and 9825, and
suffer the smae problem of a decayed captsn. There are various web pages
giving repairs using things like heat-shrink sleeving or Citroen sleeve
seals.
find any tapes to use). I'd love to get the other
two running as well,
hence the need for the service manual. All three appear to be complete
I am not sure the service manual is a lot of use now. Certainly for the
-B it's a boardswapper guidewith little real inforamtion in it.
Alas the only 90845 I have is a 0945B with the high-speed LPU. And while
I've produced as shcmatic of that, I can't produce them of machines I
don't own :-)
-tony