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

Thanks for your report, Paul. I think that it is detailed reports like these which are the most helpful to us here. Not only does it confirm Apple's commitment to getting to the root of these problems, but it also gives us a small glimpse into their behind-the-scenes operations when it comes to these kinds of incidents. I think that it is very commendable that they are willing to send someone to you in your remote location.

Your last remark is interesting. Perhaps Apple should make these forums mandatory reading for all of their Apple store personnel -- particularly their tech personnel.

Paul, is this capture human readable and are you allowed to share it with others? There are probably techies out there which could make sense on their own.

I'm curious. Has anyone here, who has experienced any of these various reported problems, taken the time to follow Apple's recommendation, and run the hardware diagnostic tool that is available by typing a "D" when you boot your machine? I'm wondering if running that test might possibly reveal any problems with the graphics card, or with any other internal components.

Other tools like Drive Genius, TechTool Pro, etc., might also highlight something wrong with the hardware.

If you have any of those 3rd party tools, just remember that Apple does not recommend booting your machine from a machine or disk which contains an OS which is older than the one that came with your Snow Leopard machine.

Hey everyone. So after my first iMac 41 (flickering issue) and my 2nd iMac 47 (really yellow), I went back to the Apple store to replace it for my third (46). This time I had them open the box to take a look before I walked out again with a faulty computer. Once it booted up, I put it to the gray bar test ( http://tapplox.com/imac-led.html ) and sadly, it also failed. You could see that the lower half of the iMac was much warmer and had slight yellowing compared to the top half. It was better in regards to the yellowing than my second iMac, but still noticeable. I also tested the display iMacs, all of which failed. Some worse than others. This yellowing issue seems to be across most iMacs, with different levels of severity.

Sadly, I opted to get my money back and wait till Apple figures it out. Good luck everyone.

When I brought mine into the Apple store they ran the diagnostic repeatedly but showed no faults, and of course, the flickering would not reproduce on the spot.

Warren:
I ran the Diagnostic Tool on it's extended interrogation of the disk - took about 2 hours. Got a clean pass with no problems found.

Rudy:
I feel I'd rather not pass around the capture file, there's probably some small print that forbids it and I don't want to incur the wrath of Apple, especially as I think they're doing their best to help me.

Very interesting indeed...

So some of the machines don't act up once they are sitting in front of an Apple tech, and running Apple's very own diagnostic tool reveals absolutely nothing.

Well, you all realize what this means, don't you?

No?

Well, let me tell you then:

*GHOSTS IN THE MACHINE!*

So, who ya gonna call???

Obviously...

GHOSTBUSTERS!!!

(Warren does an extremely poor rendition of the "Ghostbusters" theme)

Oh well, so I tried to lighten things up a little here. I think we all need it in light of nothing positive coming from Apple yet.

Come on, Steve; we're still waiting!!!

Warren Beasley wrote:
I'm curious. Has anyone here, who has experienced any of these various reported problems, taken the time to follow Apple's recommendation, and run the hardware diagnostic tool that is available by typing a "D" when you boot your machine? I'm wondering if running that test might possibly reveal any problems with the graphics card, or with any other internal components.

After I had the dreaded black out I ran both the extended hardware test and used the disk utility to check the hard drive. No problems found.

Just as an update when I had my screen flickering the diagnostic tool showed nothing, everything came back aces. I also could not recreate the issue. If anyone starts to get week 48 home, please post if you are experiencing any issues.

Warren: Yes, we're on the same side, which is why I'm pushing this. I work with statistics every day, and to me it is a clear anomaly that we have so many repeat failures for the same people while the issue doesn't seem to be very common.

You know about the Xbox 360 and the Red Ring of Death? In that case, the number of consoles that failed inside the normal warranty period was 16%. That was enough that MS took a major charge ($1.2B) to fix it, and that it was reported all over the Internet as a big deal. Not disastrous, but a big thing. Let's say that 16% of iMacs have this flickering defect - that would be a lot, and a major problem for Apple. In fact, it means that one in six reviewers would get such an iMac, and that obviously hasn't happened, so it's likely lower, but let's take 16% for the sake of argument.

16% is about 1/6, or the chance of throwing a double when playing dice. Getting three doubles in a row is not all that common. It does happen - you get thrown in jail in Monopoly for it - but it's certainly not common. The vast majority of times you throw a double, you don't throw a second in a row.

In this thread, we have several people who return a bad iMac and get a new bad model as a replacement a total of three times. That is odd, and it might be a clue to the root cause. That is the only reason I bring this up. Whether I'm right or wrong really doesn't matter to me. I came here because my iMac flickered once and mercifully hasn't ever done that again, but I'd like to know why so I know how to react if it decides to start up again.

OK for the sake of argument, not counting those that have physically damaged Imac,... How about using a really good quality Surge supressor or ups on a dedicated circuit,..ie not plugged in the the same circuit with say a laser printer , ac unit, fridge,... lets see what happens. Read many post from peeps saying the problem did not occur in store, ( some say they have instore failure which I have seen too. )

GSears wrote:
Once it booted up, I put it to the gray bar test ( http://tapplox.com/imac-led.html ) and sadly, it also failed. You could see that the lower half of the iMac was much warmer and had slight yellowing compared to the top half. It was better in regards to the yellowing than my second iMac, but still noticeable. I also tested the display iMacs, all of which failed. Some worse than others. This yellowing issue seems to be across most iMacs, with different levels of severity.

Hello GSears,

Although I haven't received my i7 iMac yet -- and probably won't until some of you here are great grandparents (sarcasm mode off now) -- out of curiosity, I went to the Gray Bar Test website at http://tapplox.com/imac-led.html in order to see what it is all about. I figure that once I do get my machine, I will want to test it there anyway.

But I did have a few questions for you regarding that site:

1. Who devised that test?

2. Is the test widely recognized by computer technicians -- particularly Apple technicians -- as being reliable and accurate?

3. Exactly how is the test supposed to be run? There are no instructions anywhere on the webpage.

4. Is "Gray Bar Test" or "Yellow Tinge Test" the official name of the test?

5. You noted that ALL of the display models failed the test. Did you inform the Apple Store employees of this? If so, what was their reaction to this? Were they even aware of this kind of test?

I am just trying to determine how much I should rely on that test, should my iMac turn out to suffer from the yellow tinge problem. I don't want to call up our AAR, just to have them go "Duh...What's that?" or say "That is not an accurate test", or some other such thing.

Thanks!

Message was edited by: Warren Beasley

ellsmako wrote:
OK for the sake of argument, not counting those that have physically damaged Imac,... How about using a really good quality Surge supressor or ups on a dedicated circuit,..ie not plugged in the the same circuit with say a laser printer , ac unit, fridge,... lets see what happens. Read many post from peeps saying the problem did not occur in store, ( some say they have instore failure which I have seen too. )

Hello ellsmako. While I can't run our equipment on a dedicated circuit, I will tell you that after running all of our computers -- and related equipment (router, cable modem, DVD burners, Iomega eGo drive, etc.) -- on those cheap $25.00 surge protectors for almost ten years, I recently purchased two much higher grade voltage regulators/line conditioners at about $80.00 each, and I feel a lot better about it. It is a "miracle" that we never lost anything over the years due to my foolish negligence.

received replacement i7 - 948 and flicker free

Hey Warren,

All fair questions. Not sure who devised this test (i found it on another discussion about the yellowing – they had also run into the issue), as it's just four bars across the screen. As for it being widely recognized, I doubt it. The test isn't run - but rather allows you to see the yellowing issue if you have it. The point of the test is that the top two bars should match the bottom two bars. In the case with my machines and the iMacs at the apple store - the gray bars on the bottom were always warmer in hue and leaned toward a yellow tinge. Again, this varied from machine to machine. My personal iMac was by far the worst, but due to what I do as a professional the yellowing of any sort was going to cause a distraction.

As for the Apple employees, yea - I made it aware to the four that were trying to help me. All agreed that they had not heard of the issue, but once I put up the bars – all agreed they could see that the two bars on the bottom did not match the two on the top. The bars are supposed to match.

You can also do a test by just making your desktop white or light gray. The bars seems to just make it more obvious and helpful. If you don't see the yellow on your screen - maybe you don't try the gray bar test... as it might make it more obvious to you. It's sort of the whole "ignorance is bliss" kind of deal. Up to you.

Good luck, hope your machine comes to you perfect and happy. If it does, I would love to know.