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yakisoto
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Posts: 5
Registered: ‎06-02-2009
Location: San Jose, CA
Views: 5,576
Message 1 of 7

T400 - Loud buzzing noise when plugging in AC adapter & charging battery

Hi, I've had my T400 (2764-CTO) for 9 months.  It came equipped with the standard 4 cell battery and 90W adapter; I've also picked up a 9 cell battery and 65W travel charger.

 

Here's the skinny: when I plug the adapter in to charge the battery, the laptop emits a buzzing sound for a few seconds - it's not the CPU whine issue, CD/DVD drive motor, CPU fan, or hard drive; the sound can be best described as a kazoo. 

 

I've tried both batteries and both adapters, and can replicate the noise when the battery is at <95% (charge point), and is being plugged in.

 

This has been happening since day 1, and I figured that it was normal.  After much searching and testing others' T400s, I'm finding that it's not.

 

Does this "kazoo" buzzing noise sound familiar to anyone?

Former Administrator
Posts: 8,592
Registered: ‎11-19-2007
Location: US
Views: 5,555
Message 2 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

Yakisoto,

 

Interesting that it occurs with both batteries and both AC adapters.   To be clear, the sound occurs only when the battery has less than 95% and is charging?  (We reduce the charge rate at around 95-96% to "slow down" the charging and take it easy on the battery).  

 

Does it matter whether the computer is on or not while charging?  Does it make the sound only when on, only when off, or in either case?

 

If you stretch out the cords so as to move the AC adapter "brick" away from the system, can you tell if the sound is coming from the PC or the adapter brick?   If from the PC, generally where on the PC?   Does your configuration have the CCFL or LED?

 

Best regards,

 

Mark

 

 

chris001
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Posts: 6
Registered: ‎04-27-2009
Location: Australia
Views: 5,550
Message 3 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

My AC adaptor on my t500 makes a constant buzzing noise whenever it is plugged and charging

 

I thought it was both but I managed to pin point it to the adaptor, and the adaptor gets very warm.. almost hot, is this bad?

yakisoto
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Posts: 5
Registered: ‎06-02-2009
Location: San Jose, CA
Views: 5,278
Message 4 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

Thanks for the replies. 

 

Mark, yes, the threshold is 95% - if I plug in while the battery level is above that (not charging), there is no sound.  I've got the LED backlight (are you thinking it could be the inverter?); I've pinpointed the sound with a stethoscope to the area surrounding the charging jack. 

 

I haven't tried charging with the system in various power states - I'll do that tonight.

 

jsad
What's DOS?
Posts: 1
Registered: ‎10-29-2009
Location: Cupertino, CA
Views: 5,223
Message 5 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

I've also been having the same problem with my T400. It is about the same age (recieved it in mid January 09), and has the same battery (4-cell). The sound is definitely not coming from the adapter, seems to be from the area where the screen is hinged to the body of the machine. My screen is LED, and processor is 2.4Ghz centrino2.

yakisoto
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Registered: ‎06-02-2009
Location: San Jose, CA
Views: 4,863
Message 6 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

Yup, sounds like the same laptop.

 

I did some testing under various power modes: With both the OEM 90w and travel 65w adapters, both batteries made the kazoo sound in all 4 power modes: full on, sleep, hibernate, full off.  I did a quick audio recording of the sound in case anyone wants to hear it.

 

What I did notice was that the charge indication LED would change colors when the noise occured, alternating between blinking green and orange. 

 

I think it might be time to call support...

markandrews
What's DOS?
Posts: 1
Registered: ‎01-17-2013
Location: USA
Views: 2,541
Message 7 of 7

Re: T400 - Loud buzzing noise when plugging in AC adapter & charging battery

Hello, I am having this same issue with my T400. The "kazoo" sound is driving me nuts... Earlier it was inter-mittent, now it is happening all the time when charging battery. If I take out the battery, the sound goes away.

 

Were you able to resolve this issue?

 

Thx

Mark

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