Processor card for a HP 9835.

Paul Berger phb.hfx at
Fri Oct 16 16:39:10 CDT 2015


Yes off-list will be good, and thanks for responding and checking.


On 2015-10-16 6:34 PM, Rik Bos wrote:
> Paul,
> I'll look for it tomorrow.
> Shall we continue this off-list.
> -Rik
> -----Oorspronkelijk bericht-----
> Van: "Paul Berger" <phb.hfx at>
> Verzonden: ‎16-‎10-‎2015 21:47
> Aan: "cctalk at" <cctalk at>
> Onderwerp: Re: Processor card for a HP 9835.
> Hi Rik,
> 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.
> Paul.

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