[vcf-midatlantic] VCF East Clinic kudos

Herb Johnson hjohnson at retrotechnology.info
Thu May 5 00:32:13 UTC 2022


[Discussion about Jonathan's S-100 workshop in the CDL facility.]

I spent time in Jon's workshop, mostly observing. I also enjoyed seeing 
the IMSAIs in repair. And it's good to see people learning to build kits 
from components.

Jon and I tag-teamed on one IMSAI fix. He was looking up details on a 
front-panel signal that wasn't pulsing; but could not find an early 
IMSAI schematic. While he was looking, I reverse-engineered the circuit 
to trace it backwards. He found the problem from the schematic, just as 
I traced it back, to the same one-shot 74121. Replacing it solved the 
problem; apparently 40-year-old monostables tend to fail, Jon said at 
the time.

There were a number of people in the workshop, exercising their 
collective knowledge of these early vintage computers. It was good to 
see them all, not just the S-100 machines. And it should be noted: there 
was a nice exhibit of early S-100 computers, thanks to Mike Loewen.

I'm certainly in favor of another workshop devoted to more 1970's 
computers, if not only S-100 computers. If it's done during a swapmeet, 
I suggest not much work will get done in the morning, people will be 
swapping. So that eats into a day of repair.

Regards, Herb Johnson
sometimes called "Dr. S-100"

-- 
Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT comcast DOT net


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