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07-30-2014

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T420s no power on AC power but power management says AC power is connected?

2014-07-30, 20:56 PM

Hi, I hope someone can point me in the right direction with a problem I have with my Lenovo laptop.

I have a T420s (Win 7 ultimate) that has stopped working. When connected to AC the battery light on the lid started blinking and stayed on but the battery was not charging, first thought was the known problems with the power manager and windows but when I changed the settings in the power manager it still didn't charge. When disconecting the battery the laptop was dead, it would only run with the battery connected but the strange thing is that it indicated that AC was connected but the system will not run on AC only? I've tried a second adapter (also 65w 20v) but that made no difference.Meanwhile the battery has run totaly empty. Leaving it unplugged for a few hours and then connecting it to AC power it gets power for 2 seconds and then dies again. Looks like a hardware problem? Any suggestions? Thanks for any help!

 

Alex

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9644 Posts

12-27-2009

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Re: T420s no power on AC power but power management says AC power is connected?

2014-07-31, 1:51 AM
Shot in the dark, but try the following.

Unplug the battery, unplug the AC.
Tap the power button ten times, then press and hold for 30 seconds.
Reattach the AC and try booting it again.

W520: 2960XM, Q2000M @ 1091/1380, 32GB RAM, 500GB&750GB HDD & 500GB SSD, FHD&MB168B+
X61T: L7500, 4GB RAM, 500GB HDD, XGA screen, Ultrabase
W550s: 5600U, K620M at 1164/1281, 16GB RAM, 512GB SSD, 3K touchscreen
X200s: SL9400, 6GB RAM, 64GB SD card, WXGA+ screen
TPT1: 1839-23U
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5 Posts

07-30-2014

The Netherlands

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  • Posts: 5
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Re: T420s no power on AC power but power management says AC power is connected?

2014-07-31, 7:55 AM

Thanks for the tip.

 

I allready tried that one and it doesn't work.

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9644 Posts

12-27-2009

CA

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Re: T420s no power on AC power but power management says AC power is connected?

2014-07-31, 17:25 PM
Maybe try pulling the CMOS battery and letting it sit overnight?

Chances are it's a more serious hardware issue, though.

W520: 2960XM, Q2000M @ 1091/1380, 32GB RAM, 500GB&750GB HDD & 500GB SSD, FHD&MB168B+
X61T: L7500, 4GB RAM, 500GB HDD, XGA screen, Ultrabase
W550s: 5600U, K620M at 1164/1281, 16GB RAM, 512GB SSD, 3K touchscreen
X200s: SL9400, 6GB RAM, 64GB SD card, WXGA+ screen
TPT1: 1839-23U
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5 Posts

07-30-2014

The Netherlands

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Re: T420s no power on AC power but power management says AC power is connected?

2014-08-02, 14:39 PM

Thanks. I'll try that when I'm back home in 2 weeks.

 

Anybody know where the charging and voltage regulation parts are located inside the T420s series?

 

Alex

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5 Posts

07-30-2014

The Netherlands

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  • Posts: 5
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Re: T420s no power on AC power but power management says AC power is connected?

2014-08-16, 11:16 AM

Well after 2 weeks vacation leaving the T420s unplugged with battery in place I plugged it in and it started charging. When it was fully charged I tried starting it, didn't start, power button blinked once and then died. Unplugged it and removed the battery, did the static discharge (power button 10 times and then holdiing it for 30s) battery in, plugged in and it starts!

It's working fine now since yesterday.

 

Cause? 

 

Thanks for the tips! 

 

Alex

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