HP-67 - 1612A03018 - Card Reader Advice Requested (was HP-67 - strange behavior)

[albertofenini]

Tony,
we re-worked all the logic board,
de-soldered all of the ICs, found little oxydation left from the previous cleaning procedure,
removed that as well, but once we have re-soldered all of the components the behaviour
remains exactly the same.
We have few working units, how can we compare a working unit with this - step by step -
to find out what's wrong with this logic board ?
Remember that when we receid the unit it was working (basic operation)
Thanks again !!!