dc adapter for nes

[tecmo super bowl]

on an ac adapter, it tells the input and output power specs. so im able to use different ones with my nes. however, with the dc adapter i have for use in the car, it doesnt have the specs on it. is there any say i could find these out? do i just plug it in and use a multimeter on it?

thanks

[Kurt_]

Pretty much. If I was to guess, I'd say the Input (duh) is 12V and the Output is somewhere between 6 and 9 volts.