iMac has a buzzing noise on the top back left corner
I have a mid 2011 27inch Imac 3.4 GHz , i7 ,8GB. Recently there has been a buzzing noise that comes out the top back left corner. when i increase the brightness of the screen the buzzing noise becomes louder when I decrease the brightness the noise stays the same.
I have seen youtube videos of people recording the buzzing noise and some say it is a faulty power supply or the LED driver board.
Has anyone heard about this? and if so where could the noise be coming from?
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6 comentários
Its the power supply for sure I lived in us never had this problem moved to a third world place with bad grounding and i find this post and similar that suspect the electric, YW
por Ari Kari
Power line noise can create issues! It can be local to you like a florescent light ballast or a noisy motor.
In most cases a good filtering UPS will solve the problem. These tend to be more expensive units! A cheap unit may not have the needed smoothing & filtering circuitry.
Have your electrician check your buildings ground as well as the wiring. Do you have the needed amperage 20 Amp for 120 Volts? Does the outlet have a good ground (three prong)?
You may want to speak with your power provider to see if you can have them put a power meter on your line to test it. Both low and high voltage conditions can effect the efficiently of your computer power supply and stress the UPS.
por Dan
Dan is right about power line noise, however I don't think an iMac is earthed, rather double-insulated. So an electrician or power supplier cannot help. The power company can help when your voltage is too high. Mine was, and they reduced it.
To check your house voltage, ask a friend who has a true AC RMS voltmeter. Not usually in an electrician's tool kit, though it is worth asking them.
Voltage changes with time of day, falling to lowest at meal times, so measure the voltage during off peak times. Some UPS have a AC voltmeter built in, so you could get a UPS first and look at the voltage yourself.
The voltage in Australia is 230 volts, though my house gets 243 volts nearly all the time.
All my Macs run well on that, but perhaps that's the reason I got noise in my iMac.
Avoid most electrical noise filters sold with entertainment electronics. Most only filter or bypass huge lightning strikes.
A UPS with good filtering also saves you from loss of data or even computer damage in a power outage.
por Kevin
Keven,
It uses ground (earthed) by using a three prog plug. Common and Ground are tied together at the fuse panel (hopefully the buildings ground is good).
So what is the function of ground for an iMac or any computer?
Grounds primary use here is to dampen noise (internally) as its path is not intended to support the power connection, think Faraday Cage. External noise is filtered by the power supply. But! Its not intended to filter away loud noise sources. This is where a good surge protector as well as UPS's can.
The type of UPS is important! As not all of them offer fill-in or clean the lines cycle frequency to fix bad power line service (high or low voltage or frequency). As an example I use APC Back-UPS Pro 1500 here in the states.
Ground it's also used as a safety path when the equipment fails or is mis-wired.
Some devices like a hair dryer are double insulated to prevent the risk of electrocution when used in a bathroom where metal fixtures are physical ground either through the piping and/or water. If that where the case the case would be plastic like the older polycarbonate cases in the old MacBooks. The current models (both desktops & laptops) are all metal cased so they can't be double insulated.
por Dan
Mine is a late 2009 27 inch. It has only recently started "fizzing", with the noise predominant along the top (and, the left top is slightly warmer than the right side). It's been switched on for about 3 months (since last shut down), going into sleep mode when not in active use. I accept that it's probably a long-term fault in the making, with also probably a Send-Away-To-Be-Fixed solution. But, in the meantime, I shut down, then unplugged the power. Then, held in the ON/OFF switch for about 20 seconds, and let the machine sit for about half a day, properly to cool down and allow any static to dissipate. Now, after switch on - nil noise/fizzing. However, will this work in the long term?
por Malcolm Gamble
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