|Re: MY HP-67 CARD READER AGAIN|
Message #2 Posted by Vieira, Luiz C. on 1 Aug 2003, 4:56 p.m.,
in response to message #1 by Jon
once we had a problem in one 82104A, the HP41 card reader (belongs to Gordon Dyer), that was detected as being the magnetic head with an open circuit, one of the coils had a broken wire. I am not sure of what procedure was taken by Gordon to identify the problem, but if one of the wires measures too high resistence to any of the other four, then you found it.
I'd guess an operational amplifier could be the "bad guy", but I do not know the card reader's circuit. I have an HP97 and if I am not wrong, the card reader in both of them is slightly different. What I can tell is that depending on the analog parts of the circuit, you may have an operational amplifier that works fine in a pre-defined gain and current conssumption (e.g. recording) and cannot keep the expected performance in another situation (e.g. reading).
Anyway, based on previous posts, I am taking a lot of care not inducting owner's to search for problems that are hard to be the cause, so I'd also suggest searching for bad contacts, head cleaning, contact strips alignment...
Oh, yes, in time: when I received the HP97 I have it was not able to read or write. At the moment it was switched to ON the card reader's pulling motor started to work and after about three to four seconds it stopped. I checked to see that all metal strips were in contact with their equivalent tabs, as if there was a card already inserted when it was switched to ON. I saw three screws above the metal strips and I adjusted them in a way the strips were close enough to their tabs without touching them. Since then it works perfectly fine, all functional. I don't think this is the same that happens with yours, but you see: the problem was much more simple than short circuited motor drivers, bad connections, controllers, etc. Only adjustment.
Hope you succeed repairing it.
Edited: 1 Aug 2003, 4:59 p.m.