determining power

I have a crappy old organ in my basement. The oscillators for the c through f keys don't work, but the drum machine works and sounds great. I have no interest in repairing the keys, but am going to remove the drum machine and make it a standalone unit. It has its own CPU and controller seperate from the organ, so getting it out won't be a problem. But I was wondering if anyone could tell me how to power it, and/or tell me to determine how much power it needs voltage wise. Thanks!

Before you remove it, just measure the voltage and current it's using with a multimeter.

If the unit has a CPU then the likelihood is it needs a 5V supply, and if the unit does not include its own power amplifier then it probably won't draw more than 500mA. Of course, that's all guesswork ;-) Are there any labels on the drum machine itself which might give us a clue?