resistance between the + and - pins where the power jack connects to the motherboard

Thread Starter

pmawhorter

Joined Sep 4, 2017
6
I'm working on fixing an HP laptop that I got for free. I have a power adapter that I know works but I'm still unable to get any power where I've tested on the motherboard. With the power jack disconnected I checked the resistance of the positive and negative pins on the motherboard and it is approximately 640 ohms. Is this what it is supposed to be or is there a short in there? Also, is there a quick way to look this sort of information up in the future?
 

crutschow

Joined Mar 14, 2008
29,818
I checked the resistance of the positive and negative pins on the motherboard and it is approximately 640 ohms. Is this what it is supposed to be or is there a short in there? Also, is there a quick way to look this sort of information up in the future?
It's difficult to come to any firm conclusions from measuring the resistance at the power input as the value can vary greatly between different designs.
And the DC resistance measured by an ohmmeter, and the resistance when powered are likely quite different.

I don't think that resistance information is ever posted by the manufacturer.
 
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