Hello all,
First of all, thank you for the schematics, it really helped. I took the
time and checked every connection between all pins of the floppy controller
part, swapped and changed the 6522 for good working ones and no luck. At
least I can now rule out a short circuit or a bad solder joint. For the
moment, the only thing I can think of is one of the static ram chips 444c-3
is damaged. I also noticed, one of the two chips is made by NEC and the
other one is SCM, on the IO Board from my LISA 2/10, the two 444c-3 are
socket-ed and both NEC chips. (this must be the reason why they socket-ed
the chips). I think one of the two 444c-3 must have been already changed by
the previous owner of the Lisa (I am starting to think this was a Lisa
assembled out of non working parts :( ). Now I only have to find two good
444c-3 chips to test with them. I will install sockets for those to be
easily changed if necessary.
If anybody has other ideas about other possible sources for this error I am
happy to hear about :)
Have a nice evening!
Alex