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01-15-2019

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W540 will run on battery or AC but not both

2019-01-15, 3:36 AM

Thank you in advance for your help. I've looked at a lot of forum posts, but haven't found an issue exactly like mine.

 

My W540 will run on battery or AC adapter, but not both. If I'm running on battery and plug in my AC adapter, my system shuts down, and I can't start my laptop unless I do the system reboot (remove AC adapter and battery, hold power button for 30 seconds). After I do this, I can either start on battery, or AC adapter, but introducing both (plugging in adapter with battery in, or plugging in battery with AC in) results in a system shutdown. I can't charge my battery when the system is shut down. I recently dropped my laptop (inside two cases), so there may be a loose connection somewhere. I feel like if AC power wasn't getting to the board, I wouldn't be able to run on AC and if battery power isn't getting to the board, I wouldn't be able to run on the battery.

 

Does anyone know of a specific connection/circuit that might be at the core of this problem? I feel like it's the system board, but not sure where to go from there....

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10715 Posts

01-02-2010

US

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Re: W540 will run on battery or AC but not both

2019-01-16, 6:15 AM

I don't have a W540 board to look at, but there is usually a collection of mosfets (power transistors) near the connectors for the A/C and the battery on either side of the board. They tend to be 8-pin and sit low to the board (short legs). I have never been successful making this kind of repair, but I have tried several times.  Mosfets are very sensitive to static electricity and are more fragile in general than most chips.


Rich


To help with forum searches, check this out: https:/forums.lenovo.com/t5/Welcome-FAQs/Using-Browser-Search-to-find-your-answers-in-Lenovo-and-Moto-Community/m-p/5016916

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2 Posts

01-15-2019

US

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  • Posts: 2
  • Registered: ‎01-15-2019
  • Location: US
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  • Message 3 of 4

Re: W540 will run on battery or AC but not both

2019-01-16, 19:57 PM

Hey Rich,

 

Thanks for your response on this. I managed to track down a couple of pics of the motherboard if you wouldn't mind looking at them. I probably can't fix this myself, but do you think a repair shop could do it?

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10715 Posts

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Re: W540 will run on battery or AC but not both

2019-01-17, 2:01 AM

I had poor luck getting this kind of repair done.  It is hard to know what chips to replace without circuit diagrams (not available).  If you can figure out what's bad, the failure is often caused by something else somewhere on the board.  My experience was that a used board on eBay was cheaper than the repar cost


Rich


To help with forum searches, check this out: https:/forums.lenovo.com/t5/Welcome-FAQs/Using-Browser-Search-to-find-your-answers-in-Lenovo-and-Moto-Community/m-p/5016916

I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
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