A600 LEDs connect

[AmiGR]

Hm, it should be very easy to find out with a multimeter/voltmeter.
Ground should be visible on the traces or the motherboard, it should be a "fat" trace. Power will always have voltage no matter what. The other two you must figure out by inserting a floppy and checking which of the two starts being pulled up (has voltage)

[AmiGR]

Eh, nope. Finding the pin that always has voltage == finding the power led Vcc. It doesn't matter if it's 5V or 2.5V or 1V. BTW, it's not /really/ a dual voltage system, it gets dimmed whenever the audio filter is on, all the blinks and stuff are just caused by (deliberately) turning the audio filter on and off.
I guess that this was originally an electrical bug on the A1000 but just looked
cool enough to keep replicating.