HP Forum Archive 06

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82104A malfunction problem Message #1 Posted by Paul Hinrichs on 21 July 2001, 8:06 p.m. A few months ago my 82104A card reader started giving MALFUNCTION, CARD ERR, and occasionally CHECKSUM ERR when I tried to read in a program. This was the first time I've ever had a problem with it since I purchased it in '82 (S/N 2204S80973. The head cleaning card didn't help, so I opened it up and found the transport roller somewhat gooey, but overall not really too bad considering its age. After cleaning everything and doing the O-ring fix it still comes back with the same errors, but not consistently. Sometimes I can get it to read a card it's rejected several times by skipping it and going to tracks 2 & 3, then it might accept it. All the leaf springs & contacts are OK and in position, the card slot is absolutely clean, wires are OK and in the right socket. I reloaded one of my programs on fresh cards and it rejected reading from one card the first time thru, but it's OK after rewriting onto the card the second time. Any ideas from you folks who seem to have much experience w/ these things. Is it possible that the head somehow got slightly magnetized? If so, how do I demagnetize it? I don't recall ever leaving any strong magnets near it. I even recently bought a 41C with cardreader thru ebay which the seller said only needed the roller fix. Did that, but I get the same MALFUNCTION error on that one, although this one I can't get to read at all. In this case I had no way to check it before the roller fix because the reader could not pull a card. (BTW, #006 rings did not work, I had to go down to #005)

Re: 82104A malfunction problem Message #2 Posted by John Ioannidis on 21 July 2001, 11:32 p.m., in response to message #1 by Paul Hinrichs When you replaced the roller, are you sure you replaced its spindle in the correct place? The thing is slightly eccentric, and controls the amount of force that is applied on the card. If you have access to a service module, you can use it to adjust the speed of the card reader. (If you don't, but are in the general NYC or NNJ area, you can use mine). /ji

Re: 82104A malfunction problem Message #3 Posted by hans brueggemann on 22 July 2001, 3:40 a.m., in response to message #2 by John Ioannidis paul, i think john is quite right with his statement. obviously, pinch roller pressure is not correct. try to give the pinch roller axis a quarter turn in clockwise direction and test the reader again. if this doesnt help, give it another *half* turn into the opposite direction and try again. you cant do any harm to the axis of the roller, because after applying one full turn to it, the axis is 'home' at the same position as before. hans

Re: 82104A malfunction problem Message #4 Posted by Tony Duell on 22 July 2001, 1:23 p.m., in response to message #1 by Paul Hinrichs Have you cleaned the head? I mean really cleaned it, not with the rediculous bit of sandpaper that HP provide :-). Take the reader apart again and clean the face of the head with a cotton bud dipped in propan-2-ol. You might as well demagnetise it when you are in there -- use one of those mains-powered demagnetisers sold for reel-to-reel tape recorders (can you still get these?). Put the tip of the demagnetiser on the face of the head, turn it on, pull it away to arms length and turn it off. Others have suggested adjusting the eccentric shaft -- for some odd reason I've never found this at all critical. Ues, size 005 O-rings are what I use -- 006 are too large. The latter are ideal for 9100 keyboards, though.

Re: 82104A malfunction problem Message #5 Posted by David Smith on 22 July 2001, 4:50 p.m., in response to message #4 by Tony Duell When using a head demagntizer it is best to turn on the unit well away from the head (arms length is good), bring it to the head and demagnitize it, move it as far away was possible, and then turn it off. When it is turned on the magnetic pulse can couple into the head and produce a HUGE voltage spike. When it is turned off the same thing happens and it will also re-magnitize the head with a vengeance.

Re: 82104A malfunction problem Message #6 Posted by Tony Duell on 22 July 2001, 5:12 p.m., in response to message #5 by David Smith Actually, I'd probably disconnect the head wires from the sense amplifier board anyway (they just plug in). The induced voltage in the head winding caused by the demagnetiser is greater than than from normal operaion (as a card passes over the head), and it might damage the chip. I take your point about the switch-on spike as well, but if you disconnect the head from the PCB it should be safe, I think.

What material for 005 rings? (Was: Re: 82104A malfunction problem) Message #7 Posted by John Ioannidis on 22 July 2001, 11:23 p.m., in response to message #5 by David Smith My favorite supplier of small parts (www.smallparts.com) has 005 rings in a variety of materials: silicone rubber, viton, teflon, buna-n. Teflon is definitely a bad choice (we want the ring to stick to the card!), and probably so is viton (that's also a fluorocarbon elastomer), but what about silicone vs. buna-n? /ji

Re: What material for 005 rings? (Was: Re: 82104A malfunction problem) Message #8 Posted by Tony Duell on 23 July 2001, 2:00 p.m., in response to message #7 by John Ioannidis The supplier I deal with (GLR Distributors) only does one type. I believe they're silicone rubber -- they're used in model steam enginesm, etc. Never had any problems with them in HP65,67,41,97 card readers.

Re: What material for 005 rings? (Was: Re: 82104A malfunction problem) Message #9 Posted by Mark Glusker on 25 July 2001, 12:58 p.m., in response to message #8 by Tony Duell Either one would work, but I would definitely use Buna-N in this application. Buna-N has good abrasion resistance and good resistance to compression set (permanent deformation over time). Silicone rubber has poor abrasion resistance. Both are the same stiffness (Shore A 70). Buna-N o-rings are black, silicone rubber are typically orange.

Re: What material for 005 rings? (Was: Re: 82104A malfunction problem) Message #10 Posted by Paul Hinrichs on 7 Aug 2001, 12:30 a.m., in response to message #7 by John Ioannidis I chose Buna-N 'cuz it was easier to find than silicone. Like Mark said in his message it's not slippery so it pulls the cards through fine, and it resists permanent set a little more than silicone does.

Re: 82104A malfunction problem Message #11 Posted by Paul Hinrichs on 7 Aug 2001, 12:48 a.m., in response to message #4 by Tony Duell Head was cleaned thoroughly w/ isopropanol. Has anyone else ever had trouble with the head getting magnetized? I don't have a demagnetizer, and when I checked @ Radio Shack I got blank stares. Anyone know a likely source for a demagnetizer? Also, I've adjusted the cam so it pulls the card through strongly without excessive "pinch". The adjustment doesn't seem to make any difference on whether a read error occurs.

Re: 82104A malfunction problem Message #12 Posted by Michael Tjebben on 7 Aug 2001, 11:53 a.m., in response to message #11 by Paul Hinrichs Paul- Yes. I posted a comment earlier this summer that I caused my card reader to malfunction with CARD ERR after having replaced the drive wheel. I surmized that the head got magnetized, because everything else seemed okay, and I got to thinking that as I was putting the screws in, they stuck to the screwdriver and I started feeling stupid!... Demagnetizing the screwdriver with a torroid, and then the head with an old Radio-Shack head demagnetizer (they had them then) worked PERFECTLY! Note, however, that some others posted later advice that it might be smart to unsolder the head to prevent induced voltage spikes from damaging the sense amplifiers. I did not to this, because I didn't think enough about this ahead of time. You might search this site for those posts (not much more than 1 to 3 months ago, I think). I did a quick search at www.radioshack.com, but was unable to find the same "wand-type" demagnetizer that I have, but they do have a small screwdriver magnetizer/demagnetizer that might help for that part of the equation. A quick search using www.yahoo.com brought up the following, which is very similar (though MUCH more expensive) than the wand I have. This leads me to believe that with a bit more searching you might find something cheap and useful: http://www.datadev.com/wd1.html Good luck! I bet the demagnetizing will correct your CARD ERR problem. It did for me (and for my father's card reader as well). -Mike

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