|Re: HP 67/97 card reader: O-rings vs. vinyl tubing|
Message #4 Posted by Michael de Estrada on 7 Apr 2010, 7:23 p.m.,
in response to message #3 by Ed Sowell
I got my last set of O-rings from Mark Hoskins (Waterhosko) on TAS. He's the guy who makes replacement battery packs for Classic and Spice series calculators.
The installed O-rings per your photo look much larger than mine, which extend less beyond the shoulder. Also, on my HP97 card reader, my O-rings barely clear the card reader frame, and I'm pretty certain yours would not, so maybe yours are rubbing, but I don't know if that would create a buzzing noise.
Yes I heard the noise and if the pressure from the oversized O-rings was sufficient to cause some slippage of the motor shaft inside the coupling (clutch), the end of the motor shaft could be rubbing against the worm gear. Or, like you said, maybe gear noise.
When I install the eccentric shaft, I use a flat blade screwdriver in the slot, and push and turn until it stops. There will be a small gap of ~1mm remaining between the shaft shoulder and the reader frame.
Hope this helps.