|Re: Do you have to "help" cards through the 97?|
Message #9 Posted by Vieira, Luiz C. (Brazil) on 26 July 2010, 12:09 a.m.,
in response to message #8 by Keith Beyer
I have a few cards that no longer read their contents, some written by the HP41īs card reader, others by the HP97.
In fact, I had the contents of some old cards (others), recorded in the 80's, recovered after cleaning them with alcohol. You'll see that the card surface reflects differently when it is dirty (flat with some spots) and when it is clean (regular and glossy, not shiny).
I just get some soft cotton with alcohol (not enough to drip, something more than moistened), then I place the cards over an absorbent, clean, straight surface (some sheets of paper over a table) then I firmly press one of the edges of the card (tip of a finger) and then I pass the cotton over the surface with a bit of pressure, in the same direction as the card is read/written (after that, clean the small surface under the finger tip the same way). I have not done it more than twice in one single cleaning, mostly because I am afraid of removing part of the magnetic material OR any protective layer. Anyway, the cotton usually comes out with dirty material on it. I never lost a card with such cleaning procedure, just have many of them recovered.
BUT if they are stored closer to strong magnetic fields OR exposed to direct sunlight for extended periods of time, chances are that their own magnetic field variations AND related contents will change. In these cases, chances are that overwriting may succeed, but it is not 100% guaranteed. Also, I am not aware of any effects on the card reader's head if the card has residual strong magnetic field after being exposed. This should also be taken into account.
Edited: 26 July 2010, 12:12 a.m.