Testing/Diagnosing your AC Adapter

Every once in a while a laptop comes in for a dc jack repair and it's simply a bad Ac Adapter. If the wire breaks internally it can give you the symptoms of a dc jack problem.
All you need for this is a simple mulitmeter. You can purchase these from somewhere like Sears or RadioShack.
Every AC Adapter has a voltage that it delivers power at. Today I'll be testing a hp adapter that runs at 18.5V. As shown in the picture you want to put the red part of the multimeter directly inside the adapter plug. On this hp adapter the plug size is 1.65mm and will need something like a small screwdriver or paper clip to get inside. Plugs that use 2mm, 2.5mm, and 3mm won't need a paper clip for this to work.
Make sure to set the multimeter to V DC (DC Voltage). Once inserted the multimeter should read close to whatever voltage you AC Adapter is. If it comes up as zero you obviously have a bad ac adapter. In this case the adapter test good at 18.89 volts.