"I have the original power adapter so once i get home in a few hours i can measure it for you

EDIT: http://www.splorp.com/newton/faq/newton ... .html#IIB7

This might also be of help, the graphic shows the pin as the positive and the shield as the negative."

This does not list the emate 300 and the previous emates say 5 volt but 7.5 will work. It does help determine that the positive is center tho. Thank you.