|HP41 Card Reader repairs|
Message #1 Posted by Steve Hunt on 1 Jan 2012, 3:41 p.m.
I just finished replacing the "gummy" wheels on my two card readers with pairs of 'O' rings. The 'worm gear' on one of them seemed loose on its motor shaft, so I used a tiny amount of 'super glue' to fix it as recommended in one article. After much tearing out of what little hair I have left, I was able to re-assemble them both OK.
Both now work reasonably well. The one which I didn't need to glue works silently; it gives occasional checksum errors, but I can live with it. The other one is quite noisy, often shows MALFUNCTION, sometimes shows CHECKSUM error, and about one time in 5 passes it works OK.
Since doing the repairs, and a bit late in the day, I've learned through old postings on this forum:
1) There is a clutch mechanism between the motor shaft and the gear; so perhaps gluing the two together was not a good idea
2) The wheel shaft is eccentric and can be adjusted using the screwdriver slot for optimum pressure on the card.
3) 'O' rings might not be the best replacement solution because they apply uneven pressure.
So now I don't know what to do:
Should I pull them apart again and swap the 'O' rings for something else? If so, what?
Do I need to separate the glued shaft and worm gear, and try to implement a replacement clutch assembly? If so with what?
How important is it to have the drive wheel position adjusted correctly? Is there a recommended way to do it.
Grateful for any advice from the group. I'm not keen to pull them apart again, but neither do I want premature wear or damage to cards.