Processor card for a HP 9835.
hp-fix at xs4all.nl
Fri Oct 16 16:34:12 CDT 2015
I'll look for it tomorrow.
Shall we continue this off-list.
Van: "Paul Berger" <phb.hfx at gmail.com>
Verzonden: 16-10-2015 21:47
Aan: "cctalk at classiccmp.org" <cctalk at classiccmp.org>
Onderwerp: Re: Processor card for a HP 9835.
As near as I can tell the connections are good, but I am pretty sure it
is the CPU, the key had fallen out of the monitor cable and I
accidentally plugged it in backwards, and when I turned it I almost
immediately noticed the smell of magic smoke escaping. The +12V
regulator was wrecked, both the 723 and its pass transistor plus a
couple burned foil traces on the power supply board. I have repaired
the power supply and all the voltages are good now, the clock input to
the CPU is good, however the clock outputs are dead, and I do not see
any evidence of life from the CPU. From checking after disconnecting
everything it appears that the +12V output went up to more than twice
its rated level. I also fear for the ROMs in the machine but I can fix
that as I had already designed a ROM card for option ROMs that I could
easily modify for the system ROMs. I am still evaluating the full extent
of the damage.
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