HP-65 1333A20064 serviced by someone ?

[GreyUser]

You desperately need a proper anti-static work surface. A fabric cutting mat and poly foam are not acceptable for handling CMOS devices, the surface charge potential of those materials is frighteningly high.

Round o-rings of the correct size are okay for DIY repairs, square o-rings are by far the best solution and are significantly more concentric and consistent than any model fuel line silicone tubing.

The correct way to determine if your replacement wheel is the correct size and that the eccentric is set correctly is to measure motor current. Apply 3Vdc supply, insert a blank card and when it has 15mm or so remaining, do not release it, hold the end of the card so it stalls under the drive wheel and observe the motor current. Set the eccentric for no more than ~180 milliamps with the card stalled under the wheel and the current should be stable. If the current is >200ma, the wheel is too large in diameter, if the current is unstable, the wheel is out of round or the drive screw is loose on the motor.

This adjustment procedure is detailed in the 82104 card reader service manual. All HP card readers are the same design so this applies to all classic, topcats, etc.

The white label with a date and two letter codes is a repair by the HP calculator service department. The codes are what was done, no list of explanations are known to exist. The green/red motor appeared only in the early 65’s. The bare aluminum version later appeared in the 67 and Topcats and then of course the 82104.