Q: New iMac 27inch screen flickering/tearing/shutoff

I say it's a power supply issue where the computer is located. Which is why the same people have the same problems with multiple computers.

I have had three of these computers. First was a core 2 that had a bad superdrive. Second had no problems but I traded it for an i5 which has had no problems since November 19th.

rickstervt wrote:
I say it's a power supply issue where the computer is located. Which is why the same people have the same problems with multiple computers.

My week 47 iMac 27" i7 experienced flickering/blackout/screen dislocation problems after applying the firmware update yesterday. This morning I called Apple Support and they asked me to bring it to the local Apple Store. I asked if the video card would need to be replaced, and the tech support person said that most likely the power inverter is to blame and will need to be replaced. This is the first time I've heard that the power inverter is to blame for this problem.

I think I've figured out a way to reproduce the problem. If I play the movie "Stranger than Fiction" at or almost at full screen, the flickering starts roughly 1 hour into the movie. Once the flickering starts, it keeps flickering until I sleep or restart the iMac.

Not sure if this makes me unique in some unwanted way but, yes, I have experienced problems after more than 6 weeks--actually, six weeks and a day, to be exact. My 27" iMac was delivered on November 19th and worked flawlessly until Christmas Day, when it began exhibiting the same problems so many have written about in this thread. I was quite surprised because it was hardly new at that point and I felt as if I had managed to avoid the iMac curse. After moaning and groaning for a few minutes (I thought Christmas was supposed to be a happy, fun-filled day), I did a Restart and the problem has not yet returned. (I had installed the update prior to the onset of problems, by the way.) I say it has not "yet" returned, because I'm assuming it will at some point. I thought about starting the whole Apple Care process and returning the unit, but given that it's not misbehaving at the moment, as well as the fact that there still doesn't seem to be a "cure" for the problem, I haven't done anything further as of now.

I have been among the quickest to dismiss heating as a major contributing factor in the flickering issue in the 27" iMacs, primarily since many users report the flickering occurs at cool temperatures, right after startup, and may not occur at all during intensive use.

I have also pointed out that location of the sensors used to monitor heat may not give a realistic indication of the heat affecting some areas of the unit.

I just sent back my week 47 flickering 27" i7, after receiving a week 51 replacement unit, also flickering.

While I was boxing up the old unit, I noticed visible scorch marks covering about 1" along the top of the display. These markings were identical to those on a 24" dual 3.06 that failed on me in October, just days prior to the i7 release date. The i7 is actually an upgrade from the replacement Apple offered me for the dual 3.06.
The markings are not visible while the unit is in use, and only became visible while the unit was being positioned back into the shipping carton. Even then, if the light had not been reflecting on the unit in just the right direction, I may not have noticed it then.

The scorch marks on the dual 3.06 occurred after a primary fan failed, causing the power supply to overheat, and damaged several internal components including the logic board, and display. I was able to observe the inside of the unit while on site repairs were being made. Several areas inside the unit had visible burn marks and after Apple made two attempts at on site repair, they decided to replace the unit. The burn marks on the display were on the display itself, and not the plastic screen covering.

The i7 with the same scorch marks on the display had iStat installed, and the temperature ranges noted were always within acceptable levels.
I would have to assume from this that there are obviously areas within the unit that are not monitored that may be producing, or exposed to too much heat. As has been mentioned on this forum before, temperatures on some components can spike at startup, and in general use, then cool down very quickly, which could explain the random appearance of the flickering, if it is heat related.

If any of you are interested, you may be able to check your own units for this type of scorching by turning the unit off, and using a flashlight along the top of the unit from different angles to search for irregularities. You will know what it is when you see it.

my power supply always seems to sit around 70c!!!

surely thats too hot and will lead to premature failure of capacitors etc???

in the uk the early sky hd boxes were manufactured with poor quality psu's and it led to a variety of things from no satellite signal, to failed recordings it led to very peculiar behaviour is what im getting at.

some of us (me included) have upgraded our psu's with decent quality caps and my box has been 110% improved!!

in 3 months it hasn't missed a single recording (used to miss them weekly)

what temps are everyone elses psu's at?

may also be worth noting that ive been playing command and conquer 3 the last 2 days solidly and ive had no problems whatsoever! with the gpu reaching 72c at one point

HAPPY NEW YEAR - EVERYONE (from Downunder)

Thought I would add this... as this topic now seems to be getting sidetracked - with redundant superflous injections.

well i dont understand your big words!!!



but happy new year from the uk..... well in 4 1/2 hrs

oh the point i was making about the psu is it can do strange things if it is playing up and starving components of what they require

Message was edited by: sparkie1984

Yesterday, after about an hour intense online video gaming, my computer started the flickering/blackout routine again, much sooner than has been my experience in the past, and I noticed that the top of the machine was extraordinarily hot. It tends to get hot, but this felt noticeably worse than usual. It seemed to me that I could faintly smell fumes, something melting or smouldering, but I chocked it up to my imagination. After reading your post I'm beginning to think it wasn't my imagination after all.

Like most, I installed the firmware update as soon as it was released, with little or no effect, but who knows, it might have failed completely by now without it.

I'm wondering now, if we continue to use these machines after the incidents start occurring does their condition continue to worsen to the point where it's not just an irritation but an actual fire or shock risk? I almost expect to see molten solder dripping out of the bottom of it.

Initially, when given the option by my Apple support worker to replace or repair, I chose repair, but I was going to wait a while for Apple to come up with a cure. Time is running out on my replace option so I'll be calling him on Saturday and crossing my fingers that the replacement is an improvement.

I think it's important to keep in mind, these are made in China, a place where melamine has been put in baby formula and pet food in an effort to save money. So really, compared to that, whats so bad about using low grade solder in a few of computers? Think what we would have to pay if they weren't so frugal . . . Just to be clear, I'm being sarcastic . . .

Message was edited by: Cuenlain

the top of mine gets very hot! where its uncomfortable to touch it hot.

but thats what you get from having the exhaust on the top i suppose, still it is bloomin warm

Melamine in the solder wouldn't surprise me a bit.

Heating on the top, and back of the machine is to be expected, since, by design, the aluminum back of the unit is part of the cooling system. The top can become very warm, even when iStat shows the temperature on internal components is within normal tolerances.

The design may be pushing the limits on it's ability to cool.

The flickering doesn't seem to be a growing problem, just extremely random. My first i7 was in use for about a month with the flickering present all during that time, and it did not seem to increase or decrease regardless of the amount of use.

I would seriously doubt that the problem would become worse, and is not likely related to the issue I had with the dual 3.06, since once that unit overheated, it went downhill in just a matter of minutes, not weeks or months, and even with it, there was no danger of shock, or even substantial smoke odor. The i7 seems to be remarkably stable, flickering and all.

Just got off of the phone with Apple Corporate Customer Care Relations, and they are still hoping for a solution soon. They, possibly inadvertently, stated that there should be a fix soon with another firmware update, or a possible revision. Yes, they actually used the word "revision".

As has always been Apple's method of operation, I would fully expect that revision to be a substantial upgrade, not downgrade or sidegrade.

So those of you who are patiently waiting for a solution, and have machines that are flickering, may be among the first to receive a new and improved version.

Hopefully.

What I would like to see is someone who experiences the flickers and also has a good Uninterruptible Power Supply (UPS) that has a display on the UPS (some have displays that show the voltage) put that display next to the iMac screen and video both the UPS voltage display and the iMac flickering at the same time. This might show whether there is some correlation in voltage in and the flickering.

For those that are not familiar with UPS's, some have Automatic Voltage Regulation (AVR), and some do not. Those that do keep the voltage within a certain range by engaging the batteries when the voltage strays too far. Others just kick the batteries in when the power goes out. Some of those with AVR can also be set to narrow or widen the range in which they allow the voltage to vary before kicking in the batteries. The upside of a narrow range is more consistent voltage to the device, the downside is shortened battery life.

Those who experience the flicker should also have their outlets checked for proper grounding and to ensure that the neutral and hot are not reversed. This can be done with a cheap ($10 - $20) plug-in device with three lights on it from a local hardware store. Even if other computers worked fine on the current outlet, it could be that these iMacs are more sensitive to less than perfect power than other computers, or previous iMacs. I am not suggesting that it is not Apple's problem if it is related to the power, but rather it is better to know the cause regardless.

Keep in mind that most UPS's have some outlets that are battery protected, and other outlets that just help reduce surges. If you are using one be sure your iMac is plugged into the outlets that are battery protected for maximum protection. This will seem counterintuitive to many, but one of the best protections you get with a UPS is from brown-outs, where the voltage is lower, but not low enough to stop devices from working. Brown-outs typically do more damage over time to electronic devices than surges, though many here may take exception to what I just stated.

It might also be valuable to see the display of one that is plugged into the same outlet that the iMac is plugged into, where both devices are plugged into the wall, instead of the iMac plugged into the UPS, while flickering.

David

I just called Apple Tech Support. He didn't know about it at first. Then he said he had heard some reports. I told him Apple needs to get on the discussion board and let people know what the current status is and if there is even a possibility of a fix. The spt rep said it was a small portion of Apple iMacs. (funny, he didn't know anything about the breaking screens or flickering issues at first, now he knows the percentages!!!) I told him that some people are on their 3rd replacement. He couldn't see how one could ... excuse me, its not just one but several. I told him I am a professional photographer and needed a better machine than what I have now. The mini-mac won't cut it and the MacPro is too expensive. Conversation basically went nowhere after that, usual rah-rah.

Idea!! maybe if we ALL called Apple Tech Support they would finally realize there is a problem (since they don't seem to currently know anything about it. Apple's solution is apparently to stonewall us with silence until they fix it, IF they can. I am beginning to wonder if the problem is hardware and is now too expensive for them to recall all iMacs (and let their stock slide) so they are hoping and praying for a software or firmware update.

Glad the Tylenol issue wasn't met with this kind of response. They came right out and announced the problem and took quick action. If it had been handled like Apple is doing, we would still be counting the dead.

sparkie-

a screenshot of the iStat widget running on my i7. As you can see my power supply temperature is at 46˚C. FWIW, the hottest thing in my computer always seems to be my hard drive.

QUOTE: "Those who experience the flicker should also have their outlets checked for proper grounding and to ensure that the neutral and hot are not reversed"

We all use 110-240V AC power supply - do we not ? (Alternating Current) prey do tell how the Active and Neutral could be reversed?