This laptop has a power problem. The battery stops charging when I move the power cord on the DC adapter. When I start moving the cord left to right, the power LED light on the front goes on and off and the battery charge LED goes on and off too.
I removed the battery and tested the laptop again. The laptop starts fine from the DC adapter when the battery is removed, but as soon as I start moving the power cord the laptop shuts off. It looks like the laptop looses power immediately.
If you have a problem like that, most likely it’s related either to the power adapter or the DC-IN power jack.
First of all, I tested the power adapter with a multimeter. The power didn’t cut off no matter how badly I moved the cord. The power adapter output voltage was 15.45VDC all the time. That means there is nothing wrong with the power adapter and most likely there is a problem with with the power socket inside the laptop.
By the way, I just purchased a brand new FLUKE 179 multimeter for less then $160 on eBay. The retail price at Sears for the same multimeter is $240. FLUKE is a really good brand. Just a side note.
Now I’m going to test the power socket inside the laptop.
In order to access the power socket I had to disassemble the laptop and remove the top cover assembly with the display.
You can find disassembly instructions for many HP, Dell, IBM, Lenovo, Sony and Toshiba laptops in these service manuals and guides.
In the laptop I was fixing (Tecra M2) the power jack is attached to a DC-IN harness and this harness can be unplugged from the motherboard.
As you see, I removed the DC-IN harness from the motherboard, plugged in the power adapter and tested continuity with my multimeter as it shown on the picture.
When the power cord is still, the voltage output is 15.45VDC, the same as on the plug.
But as soon as I start wiggling the plug inside the jack, the power cuts off and voltage goes to 0. It means, the power harness is bad.
The problem was fixed after I replaced the defective DC-IN harness with a new one.
In some laptops the power socket (DC jack) is soldered to the motherboard.
If the battery stops charging when you wiggle the power plug inside the jack, either you have a bad power adapter (test it with a voltmeter) or the power jack is broken or loose.
You cannot simply unplug the jack and replace it with another one. You’ll have to unsolder the old jack and solder a new one back on the motherboard as I described in this post.
If the power jack is not broken but loose (not making good contact with the motherboard) you can resolder the old jack without replacing it with a new one.
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