HP 9100B - Magnetic Card Reader drive wheel

[mstoer]

I have an HP 9100B and just managed to get the CRT running again (a transistor died in the HV supply). As a calculator it works fine now and mostly needs cleaning.

I am now trying to repair the magnetic card reader. The drive wheel had some kind of "rubber tire" on it to advance/eject the cards, however it completely disintegrated over the years into some kind of sticky goo. I am still cleaning it off the mechanical parts. I have an original service manual, but there is no mention of the replacement parts for this. I've been trying to guess what I should be putting in place of that "rubber tire". Googling for photos of one hasn't helped much so far. Does anyone have a card reader where they could give me the dimensions or perhaps have an idea what I might put there? I was thinking an o-ring or something similar might work.

Any tips would be great, thanks,
Marcell

[Karl-Ludwig Butte]

Hi Marcell,

HP-67/97/41 card readers often have the same problem. I used small pieces of petrol hose made of very flexible silicone as used in model making successfully as replacement. If the diameter is too small you can put a second piece over the first one.

Hope this helps a bit.

Best regards

Karl-Ludwig

[mstoer]

(11-08-2017 07:44 AM)Karl-Ludwig Butte Wrote:  Hi Marcell,

HP-67/97/41 card readers often have the same problem. I used small pieces of petrol hose made of very flexible silicone as used in model making successfully as replacement. If the diameter is too small you can put a second piece over the first one.

Hope this helps a bit.

Best regards

Karl-Ludwig

Thanks, that was a great idea. I had a suitable piece of tubing and after about a dozen attempts I managed to get it to fit nicely. I haven't tested the reader out yet, I'll do it after I clean up the keyboard and replace the register indicator lamps.

Marcell

[dramsey]

I believe the card drive wheel on the 9100s doesn't use a perfectly round shape; IIRC one side of the rubber wheel is flat. Larry Atherton would know for sure.