Bad batch of cards, or reader/writer issue?

[Dave Britten]

I've got a wallet of blank cards that I've been using with my 97 since I bought it early last year, and in going through them this morning, I'm finding that at least half of the recorded programs can't be read - so far 18 cards that are unreadable on at least one side, and usually both. These all were readable immediately after I wrote them, so it seems like the recordings have deteriorated. And I've confirmed with my 41 that I can't read them on that machine either. I haven't encountered this issue with my 65, and the batch of used TI-59 cards I bought a few months ago were all still perfectly readable on arrival (after fixing the gummed up reader and adjusting the speed).

So the question is what's more likely? Is this a bad batch of cards (maybe heat damaged at some point), or is there an issue with the writer in my 97 that's causing it to lay down weak signals that fade quickly?

[teenix]

A quick test could be writing the cards with the 65 and see how they hold up. If they fail, and you know the 65 writes cards ok, then the cards could be faulty.

If the cards stay readable, then the 97 may have problems, which could be lots of things. Aged capacitors, poor contact from the ribbon cable, failing sense or CRC chip, corrosion, dirty RW head etc

cheers

Tony

[Dave Britten]

(08-05-2021 01:41 PM)teenix Wrote:  A quick test could be writing the cards with the 65 and see how they hold up. If they fail, and you know the 65 writes cards ok, then the cards could be faulty.

If the cards stay readable, then the 97 may have problems, which could be lots of things. Aged capacitors, poor contact from the ribbon cable, failing sense or CRC chip, corrosion, dirty RW head etc

cheers

Tony

Yeah, I'll do that real quick. Could take quite a few months before I've got my answer, though.

I suspect that if there's an issue with the 97, it's mostly on the writing side of the equation, given that I can't read these cards in my 41 either. I might open it up later and give the R/W head a good swabbing with some alcohol. I wonder if I need to adjust the eccentric shaft to increase pressure against the head. Could be that it's writing weakly due to poor contact.

[BillBee]

Hi Dave,

I have had to alcohol wipe cards when I had that issue (they were of unknown age). A 41 would write and xeq vers indicated all was well. Next day I swapped the reader to transfer the program to a different 41 and "error". Alcohol wiped the card, rewrote the program and it worked. Oxidation of the tape surface?

Assuming the 41 reader was good, its just odd that both units would fail. Just thinking.

-Bill

[Dave Britten]

(08-05-2021 03:07 PM)BillBee Wrote:  Hi Dave,

I have had to alcohol wipe cards when I had that issue (they were of unknown age). A 41 would write and xeq vers indicated all was well. Next day I swapped the reader to transfer the program to a different 41 and "error". Alcohol wiped the card, rewrote the program and it worked. Oxidation of the tape surface?

Assuming the 41 reader was good, its just odd that both units would fail. Just thinking.

-Bill

Hmm, that's a good idea. Maybe I'll try wiping some of them down. I doubt that will resurrect the data that's on them now, but maybe it's enough to rejuvenate them for reuse.

Now that I'm faced with having to rekey several programs, maybe I'll take the opportunity to convert them to my 'evil' TI-59 and use up some of those blanks too.

[BillBee]

(08-05-2021 03:11 PM)Dave Britten Wrote:  

(08-05-2021 03:07 PM)BillBee Wrote:  Hi Dave,

I have had to alcohol wipe cards when I had that issue (they were of unknown age). A 41 would write and xeq vers indicated all was well. Next day I swapped the reader to transfer the program to a different 41 and "error". Alcohol wiped the card, rewrote the program and it worked. Oxidation of the tape surface?

Assuming the 41 reader was good, its just odd that both units would fail. Just thinking.

-Bill

Hmm, that's a good idea. Maybe I'll try wiping some of them down. I doubt that will resurrect the data that's on them now, but maybe it's enough to rejuvenate them for reuse.

Now that I'm faced with having to rekey several programs, maybe I'll take the opportunity to convert them to my 'evil' TI-59 and use up some of those blanks too.

I understand. I am planning on a "Wumpus" hunt for Labor Day and I only want to enter that one once.

-B

[Sylvain Cote]

My card cleaning solution is explained HERE

[Dave Britten]

(08-05-2021 03:28 PM)Sylvain Cote Wrote:  My card cleaning solution is explained HERE

Thanks Sylvain. What do you use to wipe the eraser crumbs off afterward? A dry cloth, or something like alcohol?

[teenix]

(08-05-2021 01:51 PM)Dave Britten Wrote:  I wonder if I need to adjust the eccentric shaft to increase pressure against the head.

I'm pretty dumb with things so I'm trying to get my head around how this would work.

The eccentricity cannot be the cross sectional shape of the shaft, (oval for instance) as the drive wheel won't rotate properly.

I cannot see that the shaft is bent in the middle or shaped like a single cylinder crank shaft.

That leaves the shaft of the plastic pin being offset from the oversized end with the screw slot in it. If this is the case, and assuming the 2 supporting holes in the plastic card reader moulding are aligned, then surely the shaft will not rotate in an eccentric manner, but the oversized end.

So how would this actually work?

cheers

Tony

[Dave Britten]

No idea, I just know there's some kind of eccentric shaft that can be adjusted. Not sure how or if it affects the write quality at all. Given that it doesn't appear to be related to any pressure against the R/W head, I doubt it.

[Sylvain Cote]

(08-05-2021 04:10 PM)Dave Britten Wrote:  

(08-05-2021 03:28 PM)Sylvain Cote Wrote:  My card cleaning solution is explained HERE

Thanks Sylvain. What do you use to wipe the eraser crumbs off afterward? A dry cloth, or something like alcohol?

Dry cloth.

The Magnetic Card Failures thread also contains useful informations.

[rprosperi]

I can also support the eraser cleaning method. It seems to remove thin, seemingly invisible layers of oxide that prevents clear reading (by 'invisible' I mean the eraser crumbs that come off do not appear to be excessively dirty). It works quite well, but it is VERY EASY to destroy a card, by the eraser 'catching' the card with friction and suddenly bending the card, ruining it. I recommend you practice the technique on an already known-bad card, or a new one that you can spare, in order to get a feel for what it's like. Work on only small portions (0.5" / 12-14mm) at a time.

[Sylvain Cote]

(08-06-2021 02:40 AM)rprosperi Wrote:  It works quite well, but it is VERY EASY to destroy a card, by the eraser 'catching' the card with friction and suddenly bending the card, ruining it.

I agree. I had a several hundreds cards to clean up and after destroying several cards, I came up with my card eraser jig, since then no card has been ruined this way.

[teenix]

If you hold a card at one end with a finger and drag the eraser away from that end, and don't push toward your finger, it should never bend. Swap the card over to do the other part of the same face.

cheers

Tony

[rprosperi]

(08-06-2021 03:42 AM)teenix Wrote:  If you hold a card at one end with a finger and drag the eraser away from that end, and don't push toward your finger, it should never bend. Swap the card over to do the other part of the same face.

Exactly. Though this works OK for 65/67/41 cards it's not really effective for 71/75 cards, due to length. But it's 'natural' to rub the item you are cleaning (i.e. back and forth) hence the strong warning to not do it that way.

[Dave Britten]

(08-06-2021 03:42 AM)teenix Wrote:  If you hold a card at one end with a finger and drag the eraser away from that end, and don't push toward your finger, it should never bend. Swap the card over to do the other part of the same face.

cheers

Tony

Precisely how I've been doing it, as a matter of fact. Works great! I've got a Stat Pac I coming in the mail today, so we'll see how many of those cards I need to clean and rewrite.

[cahlucas]

What you also have to take into account is (strong) magnetic fields. These can make all information stored on the cards unreadable. It seems best to me to store all cards in a metal box, which keeps out all magnetic fields. If you also add some water-absorbing granules in a cotton bag, you will probably get rid of the oxidation.

[Dave Britten]

(08-06-2021 01:07 PM)cahlucas Wrote:  What you also have to take into account is (strong) magnetic fields. These can make all information stored on the cards unreadable. It seems best to me to store all cards in a metal box, which keeps out all magnetic fields. If you also add some water-absorbing granules in a cotton bag, you will probably get rid of the oxidation.

That's a good idea. Something like a small metal cash box would be ideal, I would think. And hopefully my ham radio transmissions aren't powerful enough to scramble any cards that happen to be in the room...

[rprosperi]

(08-06-2021 12:59 PM)Dave Britten Wrote:  Precisely how I've been doing it, as a matter of fact. Works great! I've got a Stat Pac I coming in the mail today, so we'll see how many of those cards I need to clean and rewrite.

Aha, so you're the guy that beat me to that... by only seconds... good reflexes.

[Dave Britten]

(08-07-2021 02:07 AM)rprosperi Wrote:  

(08-06-2021 12:59 PM)Dave Britten Wrote:  Precisely how I've been doing it, as a matter of fact. Works great! I've got a Stat Pac I coming in the mail today, so we'll see how many of those cards I need to clean and rewrite.

Aha, so you're the guy that beat me to that... by only seconds... good reflexes.

Perhaps! I think it was just good timing that I spotted it after it was listed. I've been keeping my eyes out for that one for a while. Now I need to track down a good Applied Statistics module for my TI-59.