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.
Dwight

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