Classic HP Calculator Repair Experiences

[teenix]

(09-28-2020 06:26 AM)Kostas Kritsilas Wrote:  I used to be an electronics technologist at one point. The issue now is not ambition or ability, but vision. My eyesight is such that I have severe astigmatism, and even with semi-rigid gas permeable contact lenses, cannot be completely corrected. So I would like to have somebody who can see properly, and preferably with some experience, repair my HP-65.

The HP-80 is on its way to me now. I was told it is non-fuctional, but I don't know if it is a motherboard issue, or a battery pack issue.

I intend to keep both calculators, they will go along side my HP-35, 45, 55 (non-fuctional), HP-67, 2 HP-41CXs, 2 HP-97s, HP-48GX, and HP-35S, as well as my 2 TI-59s (one stuck to a PC-100B Printer because I don't have the key), 2 Ti-58Cs, Ti-58, TI-60, and TI-66. There is no intent at this point to sell any of them.

On most occasions it is probably dirty contacts of various sorts, corrosion on circuit board traces, broken wiring, or the gummy wheel problem. These can be fixed relatively easily. If it is a specialized component like the hybrid chip, ROM/RAM, display drivers, card reader components or LED displays these parts have to be available to the repairer as spares.

I've mended a few classics, and I would be happy to have a look at them for free, (at least to determine if it is a major problem) but down here in "Oz" most likely makes that problematical.

To get one of your Classics going, you might want to check out Harald's multi-calc, which is a drop in replacement CPU board and will give you 27 HP models to have fun with. It will work as long as the keyboard and display circuits still work.

I also have HP-55 and HP-65 drop in CPU replacement boards using a modern processor, but again, the keyboard, display circuity (and card reader) must still be functional, although there is internal storage available for programs.

Alberto here on the Forum is quite talented and has repaired/restored many HP-65's to a really good standard and might be able to offer some help.

cheers

Tony