how to use a DMM to check voltage on power adapter

[smokinkane]

I have an older laptop that even when plugged in the charging light doesn't come on. I'm suspecting the wall adapter is dead, but I just got a digital multimeter and really don't know how to use it check if the voltage is making it all the way to the adapter plug that plugs into the laptop. Can someone tell me how to use my multimeter to do this? thanks ahead of time

[jonnyGURU]

Re: how to use a DMM to check voltage on power adapter

Without stripping the wires (which is the obvious way to check the voltage,) stick one probe down into the center of the plug and the other probe on the outside.

If you look at the tip of the plug, you'll see a black ring. That ring is the insulator between the + and - metal parts of that plug. Companies make either the inside positive and outside negative or vise versa. Don't sweat it if you have it backwards because your voltage will just show up either +12V (for example) or -12V.

[tiresias]

Re: how to use a DMM to check voltage on power adapter

Yes - if you do as Jonnyguru suggested, and see that there is no meaningful voltage at the output plug, then you can try to "trace" with your multimeter where it's going wrong.

Basically, measure first at the wall socket and then at the end of the input cable where it plugs into the adapter (in the US, use the setting for 200, 250 Vac or something) - and work your way down.

The fault may well be at the charger box itself, but occasionally cables too can become interrupted.