[PDP8-Lovers] Re: how to clean a PDP8/A, dishwasher?

From: Allison <ajp166_at_bellatlantic.net>
Date: Mon Dec 17 07:55:55 2001

From: Johnny Billquist <bqt_at_update.uu.se>

>> As has been said before, what do you think manufacturers do at the end of
>> production line?
>They wash them yes. They *don't* put them in a dishwasher. There is a
>hughe difference.

Many did as it was cheaper than the commercial version.

>> Be careful about that. Allison's warning about ESD is quite real. Don't
>> even think about a feather duster; at least, not if it's a synthetic one.
>ESD should never be ignored, but in the case of computer from the 60s and
>70s, ESD is really not an issue. We don't have CMOS, we have old style MSI
>TTL here... It is not ESD sensitive. You can literally zap those
>circuits, and they will work just fine.

Sorry, not so. DEC did a study in the logistics flow to see why DOA boards
were a problem. The reason was ESD even on older PDP-8 and PDP-11
modules. The test and solution was ESD procedures or all modules and
the fail rate went down significantly. Seems for TTL while ESD generally
didn't kill it it can and did damage the passivation or input protection
leading to longer term failures that were chalked up to infant mortality.
Characateristics that were often seen degraded were input thresholds,
input sink currents, output leakage for open collector and tristate devices.
With the rarity and parts availability of older machines a bit of care is
warrented if only to reduce troubleshooting time and 90 day failures.

Received on Mon Dec 17 2001 - 07:55:55 GMT

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