Useful age of HP-41 Mag Cards?



#11

Howdy,

I have some HP-41 magnetic cards which I last wrote to on December 12th 1986. I would like to read these cards on my 41 with a newly repaired card reader (gummy wheel). When I put the cards in the reader, they pull through just fine, but I almost always get CARD ERR or MALFUNCTION.

Question:
Do I need to revisit the repair of the card reader, or is it likely that the magnetic info on the cards is degraded after 15 years?

Thanks, -mark.


#12

Hi,
My HP67 Standard Pac mag cards (same cards as used on the 41) still read fine after 24 years. Cheers. EGW.

#13

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.


#14

Hi;

after Duell's sugestions, about nothing else can be told. Just a little hunch: as Duell wrote >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, try reading your cards in another 41's card reader. If it fails, their contents are more to be doomed. Anyway, you can always re-record them, as mentioned. Maybe just the contents are lost, not the cards.

Cheers.


#15

I have had the occasional pre-recorded card that does not read. Most of the time you can re-write to them and they will work.


#16

Thanks for all the help. I tried to write a card and then read it back. The write operation has no complaints, but It gives CARD ERR for the read. So I guess I need to re-check my repair. Thanks again.
-mark.


#17

I would check the connections between the head and the sense amplifier PCB first. There are 5 wires from the head the go into single-pin sockets on the PCB (the vertically mounted PCB at the back of the reader). Often at least one falls
out when you take the reader apart for the roller replacement. If this happens, the card reader thinks it's writing on a card OK (it's not, of course), so write operations give no error, but it can't read cards, so you get an error from that.
If that's OK, check the mechanics of the card reader. Did you get the card bias springs (the curved metal springs that push the card agains the front edge of the channel) in correctly? Does the roller pull the card through
at about the right speed? (if it's slightly off, then generally the reader will be happy with at least its own cards, so an approximate check is enough at this point). It could be an electronic problem, and I can probably help you sort that out, but lets check the obvious first.

#18

I am interested to buy a card reader for HP41.


#19

Hi, Xum;

this forum is usually visited by people interested on discussions. You'll find offers for sale here. Please, forgive-me if you have alredy been there. As I have not seen your name here before, I thought this would help guiding you to the right place...

Cheers.

#20

Success! Thanks for all the help. The culprit was the copper leaf spring positioned directly above the heads. It had become somewhat flattened with age, and was not pressing the card firmly up against the heads during reading/writing. I put a bit of a bow back into it (took 2 tries to get it right), and now it reads and writes like new!

I just loaded up a WALL set labelled Dec 13, 1986, and when I did a CAT 1, I recognized almost every label it displayed. Excuse me now but I'll be spending the next few hours in a trip down geek-memory lane...

Happy Programming,
-mark (PPC #11922)


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