Is there any way to check if a power supply is auto switching multi-voltage input (120-230VAC) with an output of 6VDC? The supply is an electronic power supply (not transformer based) but has absolutely no information on it. I do not want to fry it by trying 230VAC, as it does work on 120VAC. Thanks.
There are two ways to do this check; one, of course, is to examine the power supply for a label. Most AC-input power supplies are well-labeled so that the user does not need to guess how to safely plug them in. It may be necessary to examine the very fine print, closely. It is sometimes necessary to ensure that a switch or jumper connection is made, on some older power supplies, to select a voltage range.
The other way, is to reverse-engineer the power supply, by examining the internal circuitry. Sometimes the power connector is suitable only for one national standard power connection, and examining the plug is a very strong hint.
Checking the output power is easy; just apply a voltmeter while a suitable load (usually a resistor) is attached. One would use the voltmeter, also, before touching any metal on an unlabeled box that accepts AC power, to ensure you don't get a shock.