HP-45 display issue - segments stuck on

[Dave92F1]

I don't have a battery pack or a power supply so I was giving it 3.5 volts from a bench power supply. (Maybe that wasn't enough.)

(02-19-2023 12:48 AM)teenix Wrote:  It is difficult to determine why just the LED segment lights across the entire display. It could be a short in a display module, or the keys circuit board, (possibly with the decimal point), or the Anode Driver has failed, or some other component.

If the there are no shorts and if you can test the signals going to the Anode Driver with an oscilloscope and they appear ok, then I would suspect the driver IC.

I'll check that out tomorrow. On the chance that it's an Anode Driver, are working replacement parts available somewhere?