When testing a variable voltage AC->DC adapter (the type with generic tips), I get the max 12-13 volt reading regardless of the voltage setting. This is an IMA M-100 adapter with a polarity switch and voltage increments of 1.5, 3, 4.5, 6, 7.5, 9 and 12 at 7W & 300ma. The multimeter being used to test it is a Radio Shack Micronta 22-174.
I notice the reading drops very slowly when I leave the meter leads connected, though I haven't left them on long enough to see if it finally reaches the specified voltage (i.e. 3V). The adapter works fine when hooked up to different gadgets and won't power them unless you set it as specified, so this testing "oddity" must be common. Does anyone know the reason for it?
JT