Hi,

> I have a CPU Controller card (8085 based, vintage �1987). The motor blew on 
> the 
machine, power surges came and went, and now it won't communicate with the 
outside 
world.

I think you have had some major currents flowing through ground
and electronics. Note: if you connect a PC that is grounded with
a machine, you have made a very large loop that will pickup
magnetic fields, and induce currents in the ground. This can
destroy everything. ALWAYS use optical isolation in industrial
environments.

 One chip is totally (I mean tetotally)
> destroyed, right beside the serial port. The com port on the relevant pc
> has also been blown, beacuse it was  connected at the time.

You must have had large currents. Good serial ports
can handle some light abuse. So before using your machine
again after repairing (using info of other emails), I
would suggest optical isolation. Or place the PC close to
the machine, and connect it to the machine's power.

In machines we made, we often used "opto-link", a plastic
fibre cable, with some connectors and adapters, reasonably
cheap and very reliable. The opto-coupler with the highest
max voltage available! The only minus is that I hate adaptors
(just look behind my PC, and you'll know why, adapters for:
scanner, USBhub, router, palm, isdn-modem, HP jetdirect,
fotocamera, batterycharger, bankcard reader, USB harddisk,
videocamera, digital microscope, "normal" phone charger,
GSM charger, eprom-eraser, programmer).

The easiest way to optically isolate machines is by
current loop, or by opto-couplers in the RS2323 signal path.
Email me if you want some info or schematics. I made
this before.

Regards,

Pieter Hoeben

______________________________________________

  Hoeben Electronics     Phone:   +31 6 51590081
  Ronkert 44             Fax:     +31 13 5096025
  5094 EW Lage Mierde    Private: +31 13 5096200
  The Netherlands        E-mail:  [EMAIL PROTECTED]
  http://www.hoeben.com 
______________________________________________

-- 
Author: Pieter Hoeben
  INET: [EMAIL PROTECTED]

Fat City Hosting, San Diego, California -- http://www.fatcity.com
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