Re: Useful age of HP-41 Mag Cards? Message #3 Posted by Tony Duell (UK) on 6 Dec 2001, 1:42 p.m., in response to message #1 by Mark
I have 4 or 5 HP67 program pacs. These contain pre-recorded magnetic cards, and all of them are over 20 years old.
With one exception, all the cards (about 100 total) are readable on my 67, 97 and 41s). The 'bad' card was damaged when a reader roller failed and coated the card with gunge.
So that's explainable. Of course is it possible that an external magnetic field has damaged all your cards, but I think it's unlikely.
First try cleaning the cards. Rub them _gently_ on your shirt :-). If that doesn't help, use a few drops of propan-2-ol on the back of the card and clean it with a suitable rag (or your shirt).
If that doesn't help, check the card reader again. Can it write a card and read it back? Can it read a card produced on another machine? If it fails the former test, check your work
very carefully. The leaf contacts on top of the reader mechanism, the wires from the tape head to the vertical PCB at the back of the reader (these often fall off when working on the roller). If it can read its own cards but not ones from another machine, check that the wires are connected in the right order (swapping round the 2 tracks will cause this fault, of course), check
the motor speed adjustment (preset on the main PCB) and the eccentric pin position.
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