I bought an amplifier online, and it has three wires for AC input (12V). However, there is nothing on the board about which wire is GND and which is V+ and V-.
The other connectors are for the audio channels (it has 3 channels).
How can I use my multimeter to find out which wire is which?
Is the distinction between V+ and V- necessary when dealing with AC?
I noticed that two of the wires are connected, since my ohm-meter detected resistance between them. However, since this is an amplifier I would think the circuit isn't closed before I connect speakers?