Whining noise from LCD when on less than full brightness

[Gerryn]

Hi everyone.

I got my T42 laptop about a month and a half ago. Overall I am very happy with the machine, but it has a problem which I just noticed today.

Whenever the LCD is running at a brightness level lower than the maximum, it makes a quite loud whining noise. The noise is exactly the same from level 1 brightness up to the one second to maximum. It is completely silent when on full brightness. As far as the loudness of the noise, it's not *that* loud, but I first noticed it while watching TV, so it's audible even with some noise in the background.

The reason I didn't notice this problem before was because up until now I used the machine on AC power with full brightness all the time. The LCD still makes noise unless it's at full brightness even while on AC. I can avoid the problem when using battery by changing the Bios setting to make the LCD just as bright, and leave it on full brightness, but this hampers my battery life a bit.

Does anyone else have a similar problem with their ThinkPad's LCD?

Thanks

[al7kz]

My T20 emits a whining noise when running linux. At all brightness levels. The noise stops when the computer is loading a program, like openoffice writer, then when its loaded, the whining starts up again. I just installed a 80 gb WD scorpio drive in the T20. Before, with the stock 12 gb drive in it, there was no whine, though the old drive was much noisier. The whine isn't coming from the LCD or the hard drive, as far as I can tell. It seems to be coming from deep inside, like the system board area. When the T20 is running XPP, there is no whine.

My new T42 doesn't whine, but I've only had it two weeks. As I type on my T42 I can hear a similar whine, though faint, from my 760XD parked nearby. Just about exactly the same frequency as the T20 whine.

Edit: just checked and the T20 does whine in XPP, when a web page is loaded that has flash running, even when minimized. Very faint, intermittent, mosquito-like sound. There is an extensive thinkwiki on the subject.

[Gerryn]

It's definitely coming from the LCD area, not the motherboard/CPU area.

I found that if I squeeze the case together just to the right of the left hinge, it makes the buzzing noise get quieter. Isn't the cable connecting the LCD running right through there? Do you think it may be a problem with the LCD cable?

[GomJabbar]

Try using the search button at the top of the page. Type in some search terms such as noise on battery, choose radio button Search for all terms, and choose to search ThinkPad T4x Series only. I don't have time to read through all these threads, but I "think" I have seen others report this or something similar before.

[Thinkpaddict]

Gerryn,

This is a known issue, and different Thinkpads (even within the same model) exhibit it to distinct degrees. When you reduce the brightness in your LCD this is achieved by engaging some circuitry that reduces the effective voltage you are feeding to the screen. As a result, this can produce some high frequency noise.

It shouldn't be too noticeable though. I used to have a T21 that did that quite a bit, and while it didn't bother me too much it annoyed my wife a lot (I guess she is more sensitive to high pitch noises.)