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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Notebooks > Very odd Powerbook problem -- noise related to brightness setting?

Very odd Powerbook problem -- noise related to brightness setting?
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Bob Dobbs
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Aug 17, 2004, 01:06 PM
 
Just got the Powerbook about 2 weeks ago now. It's a 15" Powerbook 1.5Ghz, 128MB VRAM, 768MB RAM (512MB crucial, 256 OEM), 80GB 5400rpm drive.

The problem i'm having is that the powerbook makes a "hissing" noise when the brightness is adjusted. Its very similar to the sound a lighter makes when you press the button down and the butane starts to come out. The noise increases as the brightness increases. I wouldn't say that the noise is noticeable with any about of ambient noise, but if you are in a quiet room, you can definately hear it. When I turn the brightness completely down and the screen is off, the noise stops. The noise is eminating from around the latch, and appears to be originating from the left side as you're looking at the powerbook with the screen open (where the adapter plugs in).

Has anyone ever heard of this? Would you guys suggest sending it in for fear of this issue getting worse? I was in an Apple store over the weekened and listened to some of the 15" they had, none of which exhibited the same issue (meanwhile getting some strange looks from the people in there i'm sure...)
     
Bob Dobbs  (op)
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Aug 17, 2004, 01:24 PM
 
something else i thought i would mention -- since i thought it might be related to feedback issues through the internal mic, i completely disabled it to no avail. the problem still occurs with input selected as either internal mic or aux input.
     
ul1984
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Aug 17, 2004, 01:46 PM
 
Originally posted by Bob Dobbs:
Just got the Powerbook about 2 weeks ago now. It's a 15" Powerbook 1.5Ghz, 128MB VRAM, 768MB RAM (512MB crucial, 256 OEM), 80GB 5400rpm drive.

The problem i'm having is that the powerbook makes a "hissing" noise when the brightness is adjusted. Its very similar to the sound a lighter makes when you press the button down and the butane starts to come out. The noise increases as the brightness increases. I wouldn't say that the noise is noticeable with any about of ambient noise, but if you are in a quiet room, you can definately hear it. When I turn the brightness completely down and the screen is off, the noise stops. The noise is eminating from around the latch, and appears to be originating from the left side as you're looking at the powerbook with the screen open (where the adapter plugs in).

Has anyone ever heard of this? Would you guys suggest sending it in for fear of this issue getting worse? I was in an Apple store over the weekened and listened to some of the 15" they had, none of which exhibited the same issue (meanwhile getting some strange looks from the people in there i'm sure...)
my 1.25Ghz 15" from last year, has a similiar noise, its just "inverted", the noise goes away at max brightness, and gets louder the lower brightness you have, and at the absolute lowest(backlight dark), its pretty easy to hear, which sucks since when i want to sleep at night, i turn off the backlight, and it gets noisy.
however sometimes its not "inverted", and just like yours (the noise is goes away at lowest brightness). over time it switches between "inverted" and being exactly like yours, no idea what causes the switch.

i think the noise is produced in a similiar way(not that i know the cause of those noises) to the "Processor Performance: Highest while on AC power" noise, and the noise you get while transferring stuff over ethernet, at high speeds(this is the loudest of the noises)
     
Bob Dobbs  (op)
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Aug 17, 2004, 03:07 PM
 
thanks for the response. I perused the apple forums and saw that others were having similar issues and suggested playing with the energy settings as well as having the computer plugged in/not plugged in. I downloaded the CHUD tools from the apple developer site, used the hardware control panel to disable processor "NAP". This did not help the sound either. Based upon one user's delemma with apple (sending it in on three separate occasions for the same issue) I dont think I will be sending it in since it is, after all, a fairly modest annoyance and does not effect the performance or general usability of the laptop. Good to know i'm not the only one in the boat though. Interesting that the other 15" in the apple store didnt exhibit the same noises tho...
     
Bob Dobbs  (op)
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Aug 19, 2004, 05:51 PM
 
anyone else?
     
   
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