Ok so i picked up a voltmeter thing, it only has settings of DCV 10,250,500 ACV 10,250,500 and DCA 500u, 10m, 250m. I tried looking through the forums and all i could come across was to put it at DCV 20 which I don't have. Should I put it to DCV 250? and also do i put the red prong in the...