I need to know the polarity of my DLink DI-704. Is the center post of the power input + or -? I have the user manual it only states 5VDC. The amperage is listed as 1 in the front of the manual and 2 at the back of the manual. Polarity is not indicated on the unit itself. Is there a way I can determine the polarity of the power inlet, using a VOM? Tom