HP card reader drive coupling

[teenix]

I mentioned this previously and agree it is not a dampener or a clutch , it is simply a shaft coupler. Considering the small diameter of the motor shaft, it would be difficult to make it any other way. The coupler is also small and quite hard so is more likely to transfer motor vibration.

I made some couplers to replace some degraded ones and if the center hole is off a bit, the shaft does obviously vibrate. However, if not too great the cards still read/write fine. The material I make it out of is softer than the original coupler, but still doesn't dampen anything. Vibration is bad of course as it is likely to damage the aging motor bearings, coupler, end float bearing and increase gear tooth wear.

HP specifies a test to adjust the pressure applied from the drive wheel to the cards and idler roller, where you have to stop the card feeding into the reader and measure and adjust the motor current. I gather this makes the drive wheel slip on the card while the adjustment is being made. Hence, why I don't consider the coupler a clutch otherwise it would slip.

Probably not a wise test nowadays as the original coupler is degrading into a crumbly material and it may fail.

I don't think HP decided that the motor would be in a stalled scenario in normal card use, so a clutch is probably not warranted. I don't think the sense chip has motor high current detect so some overheating and damage might result.

My 2 cents, I can't afford anymore ;-)

cheers

Tony