monitor hums on t22 2647-BC2

[mortal]

I noticed that when I turn down the brightness on my T22 with the function key that there ia a humming noise present that disappears once the brightness is turned to full.
If I adjust the brightness via software like KDE management settings or powerstrip that there is no humming whatsoever.Is this a quirk or a hardware problem/failure impending?

[Harryc]

Try replacing the inverter.

[mortal]

Thanks for the advice but I am wondering whether I should be looking for a new laptop as I don't want to start replacing parts on this nice but old thinkpad.

[goofyGAguy]

Thanks for the advice but I am wondering whether I should be looking for a new laptop as I don't want to start replacing parts on this nice but old thinkpad.

For less than $20 shipped on eBay plus a few minutes of your time, it seems worth a shot, IMHO.

[mortal]

That's cool. Twenty bucks is cheap.

I guess what I am really wondering is whether there really is a problem because the hum is gone, it only occurs when I use the function keys to lower brightness.

--I used powerstrip to lower the brightness and there is no humming problem.--

Why is that?

[rkawakami]

I'm not familiar with the powerstrip program but Goggling around for it seems to say that it controls the display's gamma, brightness and contrast settings. What the keyboard function keys do is to change the voltage going to the inverter, which directly causes the backlight to lower in brightness. Two totally different ways to control the relative "brightness" of the pixels on your display. From your description, it sounds like you are getting a buzz from the inverter, or possibly one of the inductors on the motherboard. Swapping out the inverter may fix your noise or it might take a component change on the motherboard.