SW - HP41-Cardreader


My Cardreader spoils the Cards with sort of grease. Does anybody know an address where I can get my cardreader repaired? Or does anybode have a hint how to repair it myself?


It is almost sure that the capstan is ruined (it is the rubber wheel that moves the card, more or less like the one in a cassette recorder). You may repair it by yourself, it is a medium-complexity project, so to speak. After disassembling the card reader, you will remove the remnant of the old capstan and put two rubber o-rings as a replacement. There is an article detailing step by step instructions to do the repair, it is referenced elsewhere in the Museum, and it works!!

See the following links:


www.hpmuseum.org/repair.htm (look for Loboyko article)


Or visit the Archive Forum 1 at the Museum, and run a search with card reader repair as keywords. You will find various interersting postings.


I have the same problem with the cardreader of my HP41cv. I thoughtt that the previous owner dropped some oil inside to let the cards go more smouthly,discovering that he had ruined the device. Where does this grease come from ? But my main question is this. How do i dissamble the cardreader? I have found the two screws at the side of the cardreader(the side that is faceing the top of the calculator).Unscrewing these wil make the upper and lower part of the cardreader case separate a little. But i am affraid of pulling them farther and crack the case. Is there any information on how to open the case of a cardreader for the HP41?

Thank's, Erwin


There are 4 little screws that you can see on the "inner" side of the card reader (the side that mates with the calculator). These tread on small metal "bridges" that connect the upper and lower part of the case. You will not see the "bridges" until the case is open. There also is a large screw behind the product identification label on the lower side.

After separating the two halves of the case, you will find two screws that hold the card drive in place. Carefully remove the five colored cables that connect the magnetic head from the printed circuit in the back (In my unit, the color order from top to bottom is RYBOK: Red Yellow Blue Orange Black), and two cables, red and black that go from the lower printed circuit board to the motor. Record the polarity for reassembly.

The cables are connected using friction sockets, remove them by pulling gently with a hemostat plier. In my unit, after two or three removals and insertions, the sockets were somewhat loose, so I soldered the cables in place. I hope you may avoid the loosening of the sockets.

You will then need to remove three screws that hold a small printed circuit board, and finally two more screws, to separate the upper and lower part of the plastic track that the card runs in. (I am describing this from memory, I hope I am not missing anything important)

There are some small plastic pieces and also metal leafs: two of these act as part of switches that detect the card presence, and a third provides a spring action on a side of the card track, to help keep the card aligned. Be very careful with this pieces, not to lose, damage or misplace them when reassembling the card reader. I suggest to take notes or to take digital photographs at each step.

The capstan is locked with a pin that seems to be a screw, but it is not, it is to be removed pulling gently. Clean the reminders of the old capstan, and substitute with two small rubber o-rings (about 6mm outside diameter, 3 mm inside diameter) At least on my case, airmodel fuel tubing was not adequate, o-rings worked the first time.

Reassemble everything in reverse order (easier said than done). Put special care on the position of a photoemitter and detector pair that sense the card presence, and... it should work!

This is an improviso writing, I suggest visiting the links mentioned on my previous message, for more detailed information.

Again, good luck! (and be very careful!!)

PS: the "grease" is the remnant of the original rubber, it fools everyone into thinking is kind of a lubricant.


Thank you for your time and effort. I have downloaded the links that you mentioned before, and together with your guidence in this massage i will try to repair the unit. I'l let you know the outcome,but it will take some time because i don't want to rush this.

Thank's again, Erwin


Take your time and obtain all tools and materials before starting. It took me *months* to find courage, materials and a 100% free afternoon :-) Some people discussed the "airmodel fuel line" vs "o-rings" approaches. In my case, the fuel line was not cylindrical enough, I had to rework everything back, and do it all again with the o-rings. Good luck again... And a reflection on magnetic media that we cannot longer use without extra effort. In the seventies, it was OK; now we should standarize on 1.44 floppies, CD-ROM and other universal media.


Anybody feel more than welcome to check out my repair techniques at my website http://community.webtv.net/lostrabbit/ it is located at the end of the page, I suggest a tetanous shot before wading through the first part of the page! Long Live the 41 and Best Regards from Mississippi USA!


Dave, I used your repair techniques a few weeks ago on my son's card reader and it works great now. Thanks! I was going to send you a postcard as you requested on your Web site, but couldn't find an address. You probably wouldn't find it too exotic anyway, as it would be from Birmingham, Alabama. :-) BTW, I spent 1976-97 in Mississippi, with the last part ('86 to '97) in Columbus.


Hey Dave, how about posting the article on your web site to the relevent Museum forum section ??. That way more people could find it easily. Cheers - John


Nah, if I did that then I would have NO chance of somebody seeing and wanting to buy all my Porsche junk cheap like! Honestly, I would be more than delighted if the museum curator took the liberty to post it to the section. Long live the 41 and Best Regards to all that are and always will be vintage HP!

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