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

Another update to my saga.

+24hrs after re-installing OSX from disc I still have no screen issues.

Really crazy to think some of these computers could have been shipped with a bad osx version installed. Must be something with the display drivers? Who knows, but for now I'm happy.

Sonics,

does that really prove that it is not the graphics card? Maybe the new one was also broken... I guess you could only prove it by putting the new graphics card into a system that was said to be "flicker-free" before.
However, I also don't think that this is a software issue. There were lots of people who claimed that with the MacBook Pro when it had similar issues and in the end it was the graphics card.

Cheers,
Rudy

{quote:title=Sonics99 wrote:}Update to my last post:

http://discussions.apple.com/message.jspa?messageID=10689477#10689477
http://discussions.apple.com/message.jspa?messageID=10687811#10687811

Replaced the video card today and the problem did not go away. This tells me it is not the video card itself (or it is all of the video cards) or Apple is shipping repurposed video cards that have not had the problem corrected.

I ordered the LCD and Display cable today and they will be here in the morning tomorrow. I will replace them and report back.

The only other things it could possible be is the inverter (I doubt), software possibly (but I have my reasons I don't believe that), powersupply (maybe a voltage regulation problem or something).

Also, the whole things has to come apart to swap the graphics card, so I took everything out and reseated everything back in. So it is not a loose cable or anything like that.{quote}

Thanks much for the update! Yours is the most useful & detailed analysis so far, and the fact that it does not appear to be the card is interesting. I look forward to the next analysis step. Apple should clearly be paying you for this...

Interesting, applestore.com says 2 weeks for all 27" models. Is the delay due to increased number of costumers or due to changes because of the display problems?

Hello Sonics99,

Thanks for keeping us informed of your progress. I appreciate it.

It will be interesting to see if you arrive at the same conclusions as Apple.

Of course, given Apple's silence, I suppose that we may never know.

On the apple Australian web site it says 7-10 business days, but when you call them they say 15th of Jan 2010 at the earliest

for now, no delay from apple italy.
22th Dec. will come. Like they said, no Delay to Jan.

Finger crossed.

Rudy Norff- You are absolutely correct. It doesn't prove anything at all. I mentioned in my post that this graphics card could be just as bad as all of the others. Maybe there aren't any good graphics cards yet, maybe there are and this just wasn't one of them. For all the time I worked for Apple, they do repurpose a lot of their parts and I have gotten bad parts.

As for the software issue, I agree. It is not a software issue directly. This does not mean that a software fix won't come. It might be something that can be overcompensated for with software. I am not beyond thinking that might be the case at this point, but it isn't directly software I do not believe.


JiminSF- Technically they are, just don't tell them. I received the full service manual for this imac and the parts list as well. I thought about posting it all here, but assume that would not make apple happy and I don't want to get anyone in trouble.

The 27" 3.06 shows 2 weeks but with the extended keyboard it shows ships in 24 hours. It doesn't look like they have stopped all 27" shipments.

Okay, as Artie Johnson used to say...."very interesting". Having dated myself, now I offer the following which may be of zero value or not.

Received my third I7 today (in all fairness or not to Apple, the first two, week 45 and 46 builds were returned for not waking from sleep and a bad DVD SuperDrive). This is version 47.

After spending some time setting up minimal applications, attempted to "stress" the machine by running Marine Aquarium screen saver. Noticed that I could make the machine display flickering/choppiness after 15 minutes. It was almost exactly on the 15 minute mark 5 straight times even when varying fps and time between attempts. So next tried three "supplied" screen savers and same behavior, 15 minutes and the display went crazy.

At this point I realized that the setting for starting the screensaver was 15 minutes. Changed to 30 minutes and wonder of wonders, the screen went crazy at 30 minutes. Verified at 5 minutes with the original screen saver (Marine Aquarium) and same behavior. Now having let the screen saver run on its own for over 10 minutes with the 5 minute trigger, and not getting the same results...

So..am I chasing windmills and someone has seen before and has a logical explanation or is there something interesting about being able to predictably cause the display to "spazz out"?

Ditto problem here. Received 27 inch Intel Core 2 Duo iMac on DEC 1st.

Thought it was some problem with my household electrics!

Have emailed Apple and will phone them in the morning.


What have people done to their iMacs before sending them back to protect their privacy/information? Reinstall the OS??

1. Hate that I got the reference.
2. While not conclusive that is interesting. Can anyone else duplicate these results? (mine is in pieces until tomorrow when I get the new parts or I would)

I don't think this answers everything but may be a clue. It leads me to believe I should have ordered the inverter or power supply actually but I flipped a coin and went LCD and display cable.

Mine has done it while actively using it and not just when it is attempting to sleep which is why I say it is not conclusive. What it does hint at though is some kind of trickle voltage issue possibly. When the machine goes to sleep the energy saver functions kick in and the system changes a handful of settings related to how the hardware works in this state. There is an attempt to save resources and drop power usage during this time. Is there some kind of communication error between the powersupply videocard and LCD? Possibly. It flickers because the signal it is receiving is saying go to sleep and then right after don't go to sleep. Could also explain some of the weird states it is getting stuck in with horizontal issues depending on when thos signals are received, etc. A millisecond different causing a slightly different response.

It would explain why restarts, pram, hitting an expose corner, and changing resolutions all seem to fix the problem at least temporarily.

Thoughts?


Edit- reminds me, mine had some gunk on the powersupply that seemed out of place and was not referenced in the repair manual. It could have been heatsink stuff but didn't match the packets I had lying around from macpro repairs I have done. It didn't seem in a place that would be harmful by any means, nor did it look harmful. It just struck me as weird and this reply made me think of it again. It is most likely not related and just heatsink goo though.

Message was edited by: Sonics99

Gavin


In the first case, zero'd out the memory and reinstalled. Unfortunately in the second, could not boot to the CD so ran a little "open loop", just deleting information which I know left me a bit exposed.

What comes to mind from the observations I witnessed, is, what are the chances, programs are hitting the same video memory registry locations and causing the display issues? If so, wondering if this could indeed be fixed with firmware that resolves the handling of conflict? A reach I am sure, but makes me wonder......?

Thanks Sooners! Sorry to go slightly off topic - how do I 'zero out the memory'.

Just a bit more info. about my problem - I'm annoyed I've waited this long to contact Apple (having thought it was an issue with my household electrics), although this is day 13 since purchase, so should be ok.

My flickering does not happen when putting iMac to sleep and waking up. It seems more random than that. And funnily enough, when it does happen, if I put it to sleep it seems to help.

I'm kind of glad I found you all with the same problem. In some ways I'm more worried, in some ways I feel I'm not alone.

Sorry, Gavin, zero'ing memory is a little bit misleading. What I meant to say, is zero out the drive which is actually re-formatting. Open utilities in applications. Then go to Disk Utilities. Once there, choose erase and then security options. You can do a one pass zero out or go crazy and do something like a 14 pass. This is almost a career move though as it takes a lonnngggg time. That said, the most secure and should I believe do the job.

Hope I explained it better this time and if not there are many smarter Mac folks here that I am sure can give you better council.