Calculator blog

Musings and comments about our common interest


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Card reader repair



Another typical problem happening with the card readers is the axis' slipping. You have already repaired the gummy wheel and you realize that the electric motor slips.

Once opened the card reader, you take the motor and pull the axis out. You will see that the inner axis attached to the motor is much thinner than the outer jacket of the screw part of the axis. (I have no pictures now but will take them on the next repair). The void between inner axis and jacket is fulled with a plastic compound that also deteriorates over time. What to do?

We have found that securing the jacket on the axis with E6000 glue works too. You need to make sure it remains straight, and that the glue does not touch the body of the motor (lest the motor gets clogged completely!). Allow 48h to dry and assemble it again. What a surprise, uh?

I will have to update the book in that chapter once I have the pictures that go with it. 

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Error in book corrected

I have found an error in the HP41 repair book - in the part referring to the card reader repair.

It is about the order or the cables leading to the electric motor. The black cable is the one furthest from the calculator; the red one is the closed to the calculator. The book said the opposite (or could be understood as the oppositce - it is strange to me since I knew the right order!

Here is a picture illustrating what I say: it is the two cables on the left. The upper part is towards the calculator.


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