hp46 with strange modification

[Roland57]

(06-28-2022 11:43 PM)teenix Wrote:  KORR might be Keyboard OveRRide.

Maybe SIN COS work on alternate keypresses of this key.

cheers

Tony

Unfortunately not. I tried every possible combination (longer press, combined press etc) - it stays with the modified behaviour.

Meanwhile I examined the modification further: the backside of the PCB says "EPIS - HP 75-000L". The traces on the keyboard-PCB to switches SIN and COS are cut and separate wires are going to the modification. A few separate wires are going from the modification to the power supply and to the logic board.

I'm going to document this modification carefully and then I will try to bring the calculator back to its original state.

Roland