HP-82104A Card Reader Repair Questions

[Hiwi]

The worm gear:

The wormgear has a small bore into which the motor axle immerses. This should run free.
There is a small piece of plastic or silicon tube that works as a clutch. This plastic is decomposed over the years. A small appropriate cable isolation or the inner part of a RG178 koax cable fits best. Put over this plastic clutch the small aluminium tube and squeeze it a bit together.
The silicon or plastic works as adhesion or grip and the bore centers the gear.

There are other options:

- You can try to squeeze the aluminium tube a bit, may be this makes the clutch stiffer.
This was also done by HP when the card reader was in maintenance.

- Some people have success with a drop of CA, to fix the worm gear to the motor axle.
Use medium ca, so you have enough time to mount the motor in the correct position.
I made this sometimes and it is a good alternative.

What is the correct position?

One end should fit into the bronze bearing without any force.
There should be a bit play or axial movement of the axle.

And the motor mount should be optimized to the lowest idle current, somewhat under 50mA if I remenber correct

Ralf