PDP-8/L repair

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Wed Jan 15 14:11:00 2003

>From: Charles <charlesmorris_at_direcway.com>
>On Wed, 15 Jan 2003 12:00:01 -0600, you wrote:
>>If you have an extender card, you should
>>be able to trace the fault pretty quickly with a logic probe or
>>an oscilloscope.
>>Without an extender card, it's a lot harder.
>I agree. I have both an extender card and a scope, fortunately,
>and have been using them extensively!
>>> This weekend, after quite a bit of signal chasing, I found that I
>>> had put the variable delay line in the wrong slot some time ago
>>> while cleaning connectors/mice nests!
>>I've done stuff like that.
>The problem was, since my machine does not come with the parity
>option installed, there are a few empty slots in the otherwise
>unbroken string of handles touching each other...I still am
>annoyed for doing it to myself though ;)
>Now to fix the core memory.
><HOPE> Shouldn't be too hard to find </HOPE>
>since it's doing nothing. If it had flaky bits or words or pages,
>different story, but absolutely dead can only be a few things.

Ya, like a broken core sense wire!

 For the times I don't have an extension card, I solder some
wires to points I expect to measure and tape them to a strip
of wood that I lay on top of the machine. It is slow but
works OK. It wouldn't work on a real fast machine because
of reflections of unterminated lines but these older machines
are not all that troublesome with one foot or so of wire.

Received on Wed Jan 15 2003 - 14:11:00 GMT

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