HP-65 card reader


Hi everybody:

I am trying to repair an HP-65. The wheel seems to be ok but the motor makes a very strong noise and it doesn´t read or write.
Does anybody know the reason for that noise?

Thanks in advance



One of several things, in the order of most to least likely:

  1. The end of the threaded drive shaft where it rests in the case, opposite the motor, needs a tiny drop of plastic safe oil. They like to squeal there (highest surface speed no doubt).
  2. The clutch is slipping. It is were the motor shaft enters the threaded shaft that drives the wheel. CAREFULLY crimping with pliers will help if the material has not disintegrated. Sometimes it is better to forget it is a clutch and put the tiniest bit of super glue on the end of the motor shaft and just glue the sucker on. Let the glue shear if it must. I doubt the worm on the capstain will break first if you don't go overboard with the glue. You can use vinyl wire insulation to make a new one in a pinch if it has turned to dust :-(
  3. The bearings in the motor are gone. Ugly. Buy a cheap 41 card read to cannibalize.

Good luck


Hi Randy:

Thanks for the fast answer.
I understand I can use the full motor coming from a 41 card reader.
In the other hand I have received another HP-65 from a friend to repair. It has the original standar pac. I have seen that both calculators can read original cards. But none of them write. However I can´t see any sign of bad function when they try to write. Everything seems to go fine but the cards are not written.
It is quite surprising. Same problem in both. May be I am not writing properly. I have written an small program and inserted the card in prog- mode. Is it ok?. If that is ok, which could be the problem?.

Thanks in advance



You mention the "original Standard Pac," reading OK, but failing to write. If you're attempting to write on the pre-recorded cards, that's the reason for your problems: they are write-protected by having the top-left corner clipped off. Any card with the corner cut is so protected.

Also, make sure the W/PRGM-RUN switch is set to W/PRGM when you insert the card.



Hi Ernie:

I have read the pre-recorder cards, but I have tried to write in non protected cards. It doesn.t write (the switch is in prog. position). Any idea?



If you get the ERROR message when you attempt to write, the problem is most likely a mis-adjusted WRITE PROTECT switch in the reader. Cards that can't be read but gave to write ERROR is most likely a mis-adjusted HEAD ENABLE switch.


Hi the problem is different. I don´t get any error message. It seems that that it writes flawlessly. But when I try to read that card later it doesn´t work. And the card reader reads ok, because it hasn´t any problem to read the pre-recorded cards... And the same situation with both calculators.
Just a question. Which should be the error message when writing?.


The 65 does not display an error message when writing like the HP67 does... some errors will cause it to flash the display. Your problem sounds like a bad head enable switch adjustment since it seems to write properly but will not read back the data (but can read other cards).

There are three switches in the reader MOTOR, WRITE PROTECT, and HEAD ENABLE. The gold switch fingers touch pads on the back of the keyboard PCB when the card is inserted. Trace the connections to the fingers on the end of the keyboard and verify that the switches open and close in sequence (to ground) as a card is manualy jammed into the reader and removed.


Screaming motors are sometimes caused by the tip of the worm gear rubbing on the ball/bearing embedded in the reader housing. Usually it is caused by noisy bearings in the motor. I use a tiny brush and paint a drop of Break Free CLP gun oil around the bearing at the motor shaft. It takes about an hour for the stuff to do its magic. Try to keep it off the motor shaft/worm gear coupling (the "clutch").

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