Take the power cord to a local electronics shop or Radio Shack and ask them if they would check it. The power cord should have 8 volts AC, 600 mA.
Problem
How To Check
Resolution
If the power cord is not producing 8 volts AC, 600 mA then you will need a replacement. If the power cord is ok then there maybe a problem with the power head. Please check out our on-line store or call Dedicated Customer Support.