My laptop doesnt detect the ac power.

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Parau_

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Apr 22, 2016
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Hello , i have a Lenovo yoga 700,14 inch , i7 skylake , 8gb ram ..blabla. and doesnt have warranty . 2 days ago it stopped detecting my power adapter. I buyed a new charger and still nothing. I also tryed to unplug the battery and plug back ..still nothing.. I have measured the voltage at the end of AC jack cable that connects to motherboard , and it gives 5v.

The adapter is usb type with a small corner on the right side. It has 2 output voltages : 20v ...2A and 5.2V 2 amps.

I only have 13% battery left on the laptop ..when is gone .. game over.

Can this be fixed somehow? without replacing the motherboard ? (coz it costs over 400$ ..)..

i also tryed to power the laptop without the battery, only with the power cable and still nothing...

Here are some photos with measured voltage , and motherboard... help me please ..

https://i.imgsafe.org/ff1b689.jpg

https://i.imgsafe.org/f9323a4.jpg

https://i.imgsafe.org/f985d22.jpg

https://i.imgsafe.org/faac730.jpg - charging port

https://i.imgsafe.org/fbd52cc.jpg

I removed the dc jack from laptop and measured the voltage... still 5V . It should give 20v ,right ? Is the jack broken or im doing something wrong ?

Here is the photo. https://i.imgsafe.org/cf7b623.jpg

The ac adapter has 2 output voltages ,5v and 20v .. i can charge my smartphone with it , but when i connect it to the laptop ,nothing happens.

Ive readed on the internet that this type of charges (usb with a small corner) has more pins that usual usb , and the charging port can also be used as usb when you dont keep your laptop plugged on the wall,so i think that this extra pins "select" the input voltage ..this means that the jack in broken? .. I dont know what to do next.. A new jack costs alot .. 30 dolars + shipping .. and i really dont want to invest more money that wont help fixing it.

Thanks.

 

Parau_

Commendable
Apr 22, 2016
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1,510
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The adapter is new(i sended the previous adapter back to the store and they gived me a new one).The previous adapter worked perfect for 20 days,and it was also brand new,i through that the power supply problem is becouse of the adapter but having another one now and the problem perisist ,im not sure what to think.. :(

Im trying to find a lenovo like mine to test my new adapter to see if it really works ,but no one has this model here.. Its too expensive and rare...

 

Parau_

Commendable
Apr 22, 2016
6
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1,510
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Ok,thanks! .. so what should i do next ? Change the DC jack ?
 
From the last picture, if you don't have 20 volts between pin 1 and 5 or any other combinaisons, without being connected to the motherboard, and if you measure directly from the adapter and you have 20 volts. You will definitely need a new jack with the cable, but careful not to short the pins on the adapter.
 

Parau_

Commendable
Apr 22, 2016
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Ok,thank you very much , i will return with info when i find a cable to replace this one.
 

Parau_

Commendable
Apr 22, 2016
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So i buyed a new AC adapter .. laptop still doesnt power up (the battery is empty now) ... i also buyed a new DC cable(jack) .. still nothing.. :( I think is the motherboard ..the charging circuit .. Can it be fixed ? (my laptop is at service now but i think they wont fix it)
 

Parau_

Commendable
Apr 22, 2016
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1,510
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I have returned with the final solution. The jack cable and the ac adapter wasnt causing the problem. The motherboard power circuit was damaged, i payed 80 dolars at the service to replace the faulty transistors / resistances .. .and now it works fine.. Thank you for you asnwers !
 
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