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HP 65 card reader tips: reinforcing the worm gear clutch

Posted by Rafa, Spain on 28 Jan 2001, 3:55 p.m.

The following tips were very useful when repairing my HP-65 card reader. Some I have discover, and some Iíve learned from others. Iíve posted them here for anyone that could be interested. I think they will serve for other HP models too.

- Reinforcing the worm gear clutch: To do this I needed a very sharpened scissors and a piece of plastic film. (I donít know the proper name in English, but it is the one that is transparent and is used in the kitchen to wrap aliments, cover bowls with food, etc. Ėthe one that sticks everywhere due to static electricity). First separate the worm gear form the motor and take a look at the little shaft that comes out of the motor. The idea is to cover this shaft with the plastic so that when the worm gear is attached again there will be more pressure and the clutch will be reinforced. Cut the plastic to make a very little rectangular piece of about 14x7 mm (patience is needed!). Fold it from the middle to make a 7x7 mm square and then cut the four corners to give it a rounded shape. Now you can see if it is the proper size by covering the motor shaft with it. If it is too large you may make it shorter, and if it is too short that covers only a part of the shaft, try to do a larger one. When you get the right one just cover again the shaft and while holding it to keep it centred reattach the worm gear to the bottom. You will need to make pressure, but be careful not to twist the shaft!. If you did it the right size no traces of plastic should be seen. (note that if the clutch is still worn you can fold the plastic two times instead of one (or zero)). I suppose this procedure is better than gluing the worm gear because the motor is able to slip in case the card reader gets stuck. And of course you can always reverse the fix.

- Putting oil: I have improved the card reader functioning by putting a little amount of oil in some strategic places. I have eliminated bad noises too. The worm gear may actually get stuck if there is some dirty in the plastic hole where it is attached (the opposite end to the motor). Iíve get good results putting oil there (just a little amount). Another place is inside the rubber drive wheel shaft Ėit must be a very little quantity or it could pass to the rubber causing the cards to slip. Finally I greatly reduced the noise of the motor by putting just a single drop of oil (caught in the head of a needle) where the motor shaft comes out (red plastic piece there). I donít know if it was a tremendous error but well, the motor rolls now very smooth and silent!.

The motor of course vibrates when functioning. If it is not well attached to the plastic structure the vibration noises are very awful. Iíve make this noise Ďcleanerí by tightening a bit more the two screws that hold the motor to the plastic structure so that motor and plastic vibrate as a single piece.

All this tips have prove successful for me, I hope they will be the same for you!

Thanks for reading

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