I have four HP 9810 desktop calculators.
Status:
1) One works
2) One starts up; lights keyboard lights; then changes the lights.
3) Two just come up with a fixed static keyboard lights.
None of the 3 that are not functioning, ever turn on the LED display. All have all cards and good voltages.
Here is my plan and I'm wondering if any damage is likely to occur to my good boards. I'd like to hear from anyone who has ever repaired any of these. Ordinarily, I would not worry about swapping boards but since many of these have problem, I'm worried that there might be some real issue with the 9810 and board swapping.
Plan:
I will remove 1 board at a time from all of the non-working machines and install them in the working 9810. That should identify which boards are bad.
Then, I will, if possible combine as many working sets as possible, to get at lease one other working 9810. I will likely offer the remaining non-working units as spare parts to anyone else who may need them. However no spares will given out until I have maximized the number of working units I can restore.
Also, these came from a 220V environment. It may be that these had 220 applied while the setting was at 120. Just a guess. Have no reason to believe this was the case, one way or the other. I did check the voltages at the top of the power supply and they are correct.
I also have about 75 magnetic cards for these. If anyone is completely without cards, I might make a few available, at no charge, just for the purpose of testing your reader.
Thanks,
Mike