Tips for Diagnosing a DC jack Repair

[Colin]

So it seems that I need a little help with this, I have got 3 Chromebooks in this week all "looks" like they need a new DC Power Jack on the motherboard.

My question is (or hope)
Can some one share the process they take to make sure that a DC jack is truly the problem and not a fried motherboard? I dont want to spend wasted time on shipping in parts if its not going to work.

the steps I currently follow:
1. Check the Power Supply with a Multi Meter
2. Dissemble Laptop and Visually inspect it for blown caps, burns, liquid damage, missing parts
3. with a multi meter test the motherboard to see if DC jack is giving power to the motherboard solder points

 

[Krynn72]

If the DC jack is broken, it will not supply power to the mb connector. You're already checking that with the multimeter, so if it supplies power then it's not the DC jack.

It's either the mb has component level failure, or the AC adapter is failing under load (multimeter can't draw enough power to really test it under similar circumstances to the laptops requirements).

 

[MichaelBits]

Check continuity between the jack and the board. It's generally easier and less risky than checking if the voltage is making it to the board.
Always try a known good power supply first to rule out the power supply.

 

[brandonkick]

Good solid info here.

First verify the voltages are proper on the AC adapter before plugging it into the laptop.
Understand that this is not under load, so it could test OK and still be a little flaky.

I like to test for voltage on the pins going into the motherboard after I verified that the
voltages on the ac adapter appear to be correct. If both look good, and your laptop still
won't power on, then you have a power supply that is failing under load, or a component
level failure on the board.

You could try removing the ram sticks. Remove the battery if it has one, and then hold the
power button for about 10 seconds before putting battery back in and trying to fire it up again.
Also try to remove everything from the slots, any SD cards, USB devices....

 

[Larry Sabo]

When testing for voltage on the motherboard, it's a good idea to use one of the power circuit ICs/fuses as a test point, rather than the DC jack pins. I've seen some microscopic cracks where the pins go into the board and you'd swear the connection was good, but it's not. (The lead in the picture in the link is less than 1mm in diameter.)