[sebhc] ET-3400A Repaired

Paul A. Pennington paulpenn at knology.net
Mon Feb 26 20:24:49 CST 2007

    I thought I would let everyone know what I finally found was wrong with 
ET-3400A, in case anyone else runs into it.  There were contact problems 
from oxidation on the chips and sockets as some have suggested, but the main 
problem was the two 2114 memory chips.  I finally tried two different chips 
and everything started working.

    I had tested the memory early on by plugging it into my ET-3400, where
it worked.  But, the clock is much slower there.  I don't know if the chips
that came with the ET-3400A are too fast or too slow, but they don't work.
A quick search on Google showed 250 nS for the bad boys and 450 nS for the
ones that worked.

    Also, I cleaned the sockets with Caig "DeoxIT" and a toothpick, and then
sprayed them with "ProGold".  I also scraped the inside of the chip legs
with a small screwdriver.

    Anyway, everything works reliably now.  That was a tough one.  At least, 
I dusted off my test equipment and got my IC tester and EPROM 
reader/programmer working again.

    Paul Pennington
    Augusta, Georgia

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