HP-67 weird behavior after reading a card

[albertofenini]

Hi Tony, Hi everyone

we are happy to say that now it works !!
yesterday we replaced the couple 1818-0231 and 1818-0232
with the donor chips but the behavior was the same

today following Tony's suggestion we replaced the couple 1818-0550 and 1818-0551
with the donor couple 1818-0226 and 1818-0228 and now the board works
fine, can read and execute programs stored even on two sided cards

since we didn't test it after replacing the first of the two (1818-0226) we cannot
say which one of this pair was faulty, but it may be safe to say that
couple of chips we replaced yesterday were good

again thank you very much to everyone for the suggestions received

will try now to fix the other unit that let card slip out of the card reader with a consistent error message ...

take care !