On 12/01/2010 07:35 PM, Lloyd E. Sponenburgh wrote:

I finally tracked it down to a broken feedthrough on the board. I
installed the traditional "patch jumper" made of wire-wrap wire, and it
worked.

Dang! After over 20 years off-duty, I can still do it.
Well, its days are numbered. How many OTHER bad feedthroughs are
lurking in there? Geez, if all the chips are socketed, it is a miracle
it still works at all. Most of this old stuff, the MTBF starts to head
down faster and faster.

I had an Allen-Bradley 7320 control that started to have a lot of
failures, and I was SURE glad to retrofit it with something more
maintainable.

Jon