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iMac vs. Electricity

CartoonChess

CartoonChess

macrumors member
Original poster
Jan 31, 2006
47
6
Seoul
Hi everybody. Today I experienced a lovely upgrade from an iMac G4 to the new 3.06. Basically: Yay.

The big problem facing me right now has to do with electricity. I'm no electrician and so I have no idea how any of this works, but here goes. When the new iMac's display goes to sleep, it emits a short buzzing sound from somewhere around the top-left corner, approximately every two seconds. The lights in the room flicker during this.

This house was built somewhere around 1970 and I have no knowledge of the electrical wiring ever having been changed (but I don't really know as I've only been here seventeen years). In the winter, when the furnace kicks in, usually some light can tip you off for a second. Same thing happens with the microwave.

Right now the new iMac and the old one are plugged into a power bar together (with a set of speakers/subwoofer, though I'm not listening to anything) and are therefore using the same electrical outlet. However, previously I had been running the old iMac with the speakers and a PC with a 19" CRT on the power bar without problems (the G4's display sleeps as well). This only happens while the aluminum iMac's display has gone completely black, and starts immediately. At first I thought maybe it was a fan, but it doesn't really sound like it. I think I read somewhere that the top-left is where the power supply is.

The new iMac is fairly hot on the sides and the top can't really be touched for very long before you're sure it'll become a burn, but I think that's actually normal. Mind you, all I'm doing at the moment is Safari and Mail (and I haven't moved any data over, so Spotlight is relaxed). There's no UPS in this setup and the light fixture in question is on the ceiling with two incandescent light bulbs. The Intel machine is positioned just in front of an enclave in the desk setup and, while the top fans are roughly two inches away from the overhanging portion of the desk, all feels cool behind the machine.

Sorry for writing a book, but I wanted to supply as much information as possible in hopes that someone with electrical knowledge or otherwise might have an idea on whether it's the machine, the house, or whathaveyou. I suppose if it's the house I'll just have to force the display to stay on always. I imagine that isn't healthy for the display, but is it liable to die off before four or five years have passed and a newer machine comes along?

If anyone has any thoughts, I'd really appreciate it. Thanks.
 
Have you tried to use the iMac in another part of the house ( another power outlet ) to see if the
problem persits


-- learning english.. sorry for mistakes :rolleyes:
 
Currently I am typing from a new room in the house. The iMac continues to make the sound and the lights flicker here, too. Whatever is in the top-left of the iMac, I can hear it much more clearly now by putting my ear close to the case. I sounds like something is definitely shorting out electrically.
 
Thanks richthomas, I think I will do just that. By the looks of this prototype photo, it is indeed the power and such in that corner. Guess it doesn't like not having to power the display.

So much for wishing it to cure itself. Now the waiting game begins again . . .
 
Given the age of your home's electical wiring it may be wise to invest in some surge protectors
 
I was looking to get the 3.06 imac as well. Does it really use that much electricity?
 
Angelward: I won't pesker you for specifics, but is that an expensive proposition? To be fair, this is the only time I've had an issue like this.

M-apple-T: I think the buzz is that these are power-hungry processors compared to their predecessors, though maybe I read wrong. Anyway, this is hopefully a one-machine issue. I can't imagine even the sound it's making is usual.

UPDATE:

Called Apple. They blamed the flickering on the wiring in my house (it's from the seventies and therefore likely aluminum, which, coincidentally, doesn't play well with the aluminum iMac). As for the buzzing, they said it isn't normal. It's going for repairs. Thanks for the help, everyone.
 
Same Problem here

I realize that this is an older post by I too am having the same problem. I purchased the 24" 2.8 iMac back in April and I have been amazed about this issue since the moment I plugged it into the wall. I do not get any buzzing but every time I put the computer to sleep is makes all the lights on that circuit flicker about every 5 seconds. As soon as you move the mouse or wake the iMac the flickering stops. It happens on every circuit that I have in the house. I can assure you that it is not my wiring. I could understand if it did this while the computer was awake and computing but it does this only when it is asleep, and starts immediately when put to sleep. Now that makes no since that the computer will draw more power while asleep.
 
You can get a good multi port surge protector for under $20. Great investment considering it can protect your thousands of dollars worth of electronics.
 
As the OP figured out for his iMac, the problem is most probably related to a defective power supply/voltage regulator. You should contact Apple support to get it repaired while it is still under warranty.
 
geoffreak said:
You can get a good multi port surge protector for under $20. Great investment considering it can protect your thousands of dollars worth of electronics.
Click to expand...

Better yet, take that $20 bump it up to about $100 and get an Uninterruptible Power Supply (UPS). Much better investment if you ask me. Surge protectors only protect you from power spikes. A UPS with automatic voltage regulation (AVR) will protect not only from power spikes but dips in voltage.
 
Got UPS???

HereComeTheBugs said:
Better yet, take that $20 bump it up to about $100 and get an Uninterruptible Power Supply (UPS). Much better investment if you ask me. Surge protectors only protect you from power spikes. A UPS with automatic voltage regulation (AVR) will protect not only from power spikes but dips in voltage.
Click to expand...

Yeah that's all great but it's not my power that has a problem, it's the iMac. I have two UPS systems with internal surge protectors and yes I recommend every one use a UPS. I don't really feel comfortable plugging the iMac into either UPS as it is obviously drawing to much power while in sleep mode. This can cause several problems! One it can shorten the life of the UPS unit as it is constantly trying to balance power to a unit that it sporadically drawing power. Two it can pull to much power on the other side of the UPS and cause potential problems with other devices that are plugged into the UPS.
 
Hey fellas,

Sorry to bump this up but I feel it describes my situation best. Hope someone can help.

Recently I started getting that same little buzzing noise from my iMac and by the sounds of it it's coming from the power supply DC/DC converter(?). The sound is always there whether the iMac is on, off, sleep etc. Only time it goes away is if I plug it out of the mains.

Now here comes the twist. My PC's speakers make a very, very similar (almost static like noise) if I plug them in the PC's speaker output jack. Started round about the same time as the imac. Both PC and iMac are almost next to eachother drawing from the same mains (two separate plugs though). The speakers make the same sound when plugged into either the PC or iMac hence it couldn't be the sounds card. They seem to be picking up some sort if interference. Could it be the same one making the iMac buzz? Is it underpowered?

Only recent addition to my settup was a TC but I doubt that can cause it.

- Could it be a problem with the mains in the house or a faulty device somewhere? It's a relatively old structure (+/-30-40 years)?
- Is it dangerous?
- Would a UPS fix it by equalising the voltage, etc.


Thanks for any help, fellas.
Much appreciated

Arc.

Ok, just a quick update to the post above:

The buzzing noise from the top left corner of the iMac is now gone and so is the static noise (virtually same noise) from the PC speakers.

Could it be some sort of interference when another electrical device is on or simply a drop in the Mains voltage?

Speakers made the same sound when plugged into both the iMac and PC.
 
Since you said "mains" I must assume you're in the UK. Normally people in the US say "line" or "outlet." Just one of those things.

I imagine (but have no experience on the matter) that a good power supply set to 240V would have a tolerance range of 210V to 250V. If you have a voltmeter/multimeter, I would take a reading of the voltage coming from the outlet the iMac is connected to and see what it reads. If it's between 220V and 240V, the electricity coming from it is probably good enough to run the iMac without issues.

Now you can skip the rest of this post if you wish.

In the UK all lines use a 240V circuit. All power supplies manufactured for PCs and Macs alike have a red dip switch on the back for changing between 120V and 240V settings. Since it turns on and doesn’t short out and produce smoke, I must assume the switch is set correctly. (Just a quick bit of trivia there so you know a little about how it works.)

A good power supply in 120V mode can handle ranges between 110V and 135V. In my house the electricity coming from the outlet is usually around 132V, not 120V. Because of this I've had some (cheap) power supplies bite the dust on me. A good power supply can also handle spikes in excess of 200V, which occur on a daily basis even in industrialized areas. (This is why you don't set a voltage regulator to 130V; you'll shorten its lifespan considerably in doing so. Instead set it to 200V.) Your power supply is not as sensitive as you'd think.
 
ArcspacE said:
Ok, just a quick update to the post above:

The buzzing noise from the top left corner of the iMac is now gone and so is the static noise (virtually same noise) from the PC speakers.

Could it be some sort of interference when another electrical device is on or simply a drop in the Mains voltage?

Speakers made the same sound when plugged into both the iMac and PC.
Click to expand...
Sounds like a ground loop issues. Google "ground loop" for various solutions.

JacaByte said:
In the UK all lines use a 240V circuit. All power supplies manufactured for PCs and Macs alike have a red dip switch on the back for changing between 120V and 240V settings. Since it turns on and doesn’t short out and produce smoke, I must assume the switch is set correctly. (Just a quick bit of trivia there so you know a little about how it works.)
Click to expand...
Most Macs have auto-switching supplies these days. No more dip switches.
 
flopticalcube said:
Sounds like a ground loop issues. Google "ground loop" for various solutions.
Click to expand...

Thank You, will do.
But if is a ground loop problem, could it be auduible (as it is) through the iMac's power supply/inverter?


Is a ground loop dangerous to the iMac in general?
Would an UPS eliminate this problem?
 
flopticalcube said:
No.

It might. You should probably have a UPS anyway.
Click to expand...

Thank You very much for the info.

But if it is a ground loop (pretty certain of that by now) should it not be audible through the iMac's built-in speakers and not the Power Supply/Inverter (top left)?
 
Hard to say if its not ground loop related. Try a different power outlet on another circuit. It could be a loose part. Does the humming change when you change brightness on the screen? An faulty inverter may hum on low brightness but be silent on high.
 
It isn't brightness related.

The buzzing comes and goes at random times.

If I unplug the iMac completely from the wall, I can still hear the buzz on my PC speakers.
 
Tried another plug but still the same hum. I guess it's all on the same circuit.

Could prolonged exposure to ground loop damage the inverter?
 
Thank You very much for all input.

Will investgate further and perhaps consider an UPS system although some suggest it wouldn't fix a ground loop issue. Oh well.
 
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