I have a display from an old radio (I think it was a Watson).
Now, there are different wires connected to it: Let's call the first two A and B and one of the others (it seems to be not so important which you choose) C.
If I connect A to the (+) of a power source and C to the (-), LED M lights up. If I connect B to the (+) of a power source and C to the (-), LED N lights up. Using that technique, I can light up any LED on the display. (Connecting A or B to (-) and C to (+) yields no results). Also note that the display does not need a binary encoding (i.e., voltages LLHL -> number 2 on display); I am able to light up an arbitrary segment.
However, I can only light up one arbitrary LED; If I wanted to choose two arbitrary LEDs, I would have to connect for example A and B to (+) and the other wires C and D to (-). As one might expect, four LEDs light up, as a current flows from C to A but also from C to B and from D to B and also from D to A. Therefore, four LEDs light up.
Does anybody have an idea about how to control this type of display correctly?
There are also some notes on the back: AV-923A8Y, SB 98 IHB, E228731. However, I did not find any suitable (and free) data sheet.