HP-82104A Card Reader Repair Questions

[Papymouzot]

Hi everybody,

I finally had some time today to run some tests and adjustments as you advised.

Note: In the meantime I received another card reader, a younger one, serial 2548S while the two others were 2052S and 2040S (both non working). The one I managed to make work once the gummy wheel was changed and a bit of cleaning is 2640S.

I opened the latest one I received, removed the gummy wheel which was very sticky, cleaned everything, inserted a bit of silicone tubing I got from an Internet contact (thanks to him) on the black wheel (same tubing in the 4 readers) and tested it... same punition as the two others : CARD ERR. I did apply a very small quantity of teflon grease on the worm gear and on the axis of the little white plastic wheel on both units plus at the end to the worm gear. I did not open the part where the card goes through just in case the pressure applied by the screws would change something.

So... the tests results. The latest one I received: Card reader Serial 2548S

Using regulated lab power supply set to 3V

Running motor with no card inserted : current equal around 80-90mA
When I insert a card, it goes up to 170-180mA
Turning the eccentric pin makes little change unfortunately, I can go up to 100mA with no card and 180-190 with a card, I never reached 200mA
CAT 2 tells me CARD RDR 1G Motor is German
Inserting a card gives CARD ERR.

With the Card reader serial 2052S

Running motor with no cards: current equal 120-140mA, this is much higher than the other one!
When I insert a card it goes up to 240-290mA
Turning the eccentric pin makes very little change
CAT 2 tells me CARD READER
The motor makes at times much more noise than the newer one. On this old one, motor is Swiss, when I touch with my finger the brass gear without applying pressure (motor outside the unit), the noise reduces drastically and current goes to 80-90mA
The motor, removed from the unit consumes 30-40mA when I don't touch the worm gear. I therefore checked the piece (hole ?) where the end of the gear goes, I tried to clean it and reapplied teflon grease. There is a little play along the motor axis so the brass work gear isn't blocked in the "hole/bearing". I don't really understand why the current doubles when the motor is attached to the unit. Once I put the black wheel inside the unit, current goes up again... Although the wheel seems to turn freely, I also applied teflon grease to the inside of the black wheel with no improvement.
Inserting a card gives CARD ERR.


The electronics and motors are different in the two units.