Unibody macbook pro 2.53 9600gt screen flickering

Discussion in 'MacBook Pro' started by Edwardish, Jun 23, 2009.

  1. Edwardish macrumors newbie

    Aug 28, 2008
    HI everyone there, i have problem with my unibody 2.53. I am using archicad for my designing works problem arise is when i do editing in 3d or rotating in 3d shade mode... my screen flickers like crazy... i am not sure whether its the firmware or hardware problem...Problem ONLY arise when doing 3d works. Please help.
  2. AlexRichter Guest

    Jun 25, 2009
    I have the same issue, is it the new unibody or the old one?
    Took mine into the Apple Store today, and the guy had no clue... they are replacing logic board. Not holding my breath.
  3. Frosties macrumors 6502a


    Jun 12, 2009
    Someone with a spotlight flicker issue had an Apple tech try 10.5.6 instead of 10.5.7 through firewire mode and that worked. It was said in that post that it was believed to be a software issue and 10.5.8 had new drivers listed. Perhaps this will mend your issue as well, let's hope.
  4. AlexRichter Guest

    Jun 25, 2009
    I have owned that macbook since before this update and the problem existed. It's definitely a hardware issue. Thanks for the suggestion though.
  5. andrew upstairs macrumors 6502

    Feb 3, 2009
    Downtown Los Angeles
    I'm having the same flicker issue with the 9600m, on a 2.66.

    This MBP was a replacement for a 2.53, which had the flickering on the 9400m.

    Unfortunately, I discovered it on this one way past the 14-day window.
  6. Frosties macrumors 6502a


    Jun 12, 2009
    Someone with a theory at apple discussions.



    Posts: 2
    From: MI
    Registered: Jun 21, 2009

    Re: screen flicker resolved?
    Posted: Jun 21, 2009 7:45 AM in response to: Jeff Storm
    Click to reply to this topic Reply email Email

    Hopefully I can shed some light (no pun intended) on the backlight flickering issue at low brightness. I have designed fpga controllers for LCD panels, and the issue is a combination hardware/firmware issue.

    I purchased a uMBP in October and never saw any backlight flickering at low brightness with either GPU. I just received a newer uMBP and it shows the backlight flicker problem only on the 9400. It was immediately obvious what the problem is. The LCD panel has an underlying repetition rate as does the LED backlight controller since it uses PWM techniques to dim the lamps. Apple did not provide enough filtering on the LED PWM controller so the LED's are actually slightly flickering on their own at the rate of their PWM controller. This is not a problem on it's own as the PWM frequency is always high enough that the human eye can not perceive it. The problem is when this frequency or it's harmonics are close a frequency of the LCD, patterns will be created in the light intensity called beat patterns. Since these beat patterns are dependent on the absolute frequency of the LCD and LED PWM, and since each GPU and the LED PWM are sourced from different clocks, the issue will be different for every motherboard, and will vary with such things as voltage and temperature.

    I verified my suspicions by slightly shifting the operating frequency of the LCD (not something anyone can do) and the problem went completely away. As I continued to change the frequency the problem would reoccur and subside as the two fundamental frequencies would beat against each other.

    The solution would have been to provide better filtering of the PWM supply, but this is a typical trade off that even I would have made when designing a PWM dimming circuit. Also, typical white LED's have a fairly slow response time, so this was probably relied upon for some of the filtering. The other solution is to just shift the frequency of the LCD or LED PWM so that they don't beat. The problem here is again with the absolute frequency (over time, temp and voltage) on each motherboard.

    So the bottom line is an LCD replacement will not affect this issue at all (although it may address some of the other issued raised in this thread), and a motherboard replacement is a hit or miss proposition at best, (unless Apple has made a hardware changed, but based on my new uMBP, they haven't) and even if it does appear to fix it at first, it may return later. My guess is (and this is only a guess) a firmware change could be made to shift the clocks to alleviate this problem. This is something I have done to my firmware designs, but is not always possible for other engineering reasons. Certainly the LCD clock rate can be shifted easily, but what complicates the solution is it needs to be universal across all notebooks and that can be a difficult thing to achieve.

    So can anyone confirm that they have spoken to someone at Apple that has confirmed they know of the issue and are actively seeking a solution? Without this confirmation, I don't intend to send my MBP back as it can be a futile exercise as pointed out by others in this thread.

    MacBook Pro Mac OS X (10.5.7)
  7. AlexRichter Guest

    Jun 25, 2009
    Seems like a reasonable explanation.

    Can anyone with a 2009 uMBP confirm if they still suffer from this issue?
  8. jgo78 macrumors 6502

    Nov 11, 2008
    what kind of flicker is it? Is it the fast pulsing/strobing at low brightness levels?
  9. Baggy Spandex macrumors 6502

    Baggy Spandex

    May 23, 2009
    FWIW, my brand new 2.53 UMBP had a flicker problem. The screen would flicker a bit, then there were lime green lines developing around image details. Eventually the whole LCD would get a green cast to it. Nuclear green, not a little tinting. Probably GPU issues, no?

    Either way, I took it to the Apple store 3 days after purchase and they replaced it no questions asked. They said usually within 14 days they're pretty good about just giving a new computer instead of repairing. I was in and out in under 3 mins.
  10. clyde2801 macrumors 601


    Mar 6, 2008
    In the land of no hills and red dirt.
    I imagine this is how Worf felt when Data, Wesley or Geordi gave some long explanation of why something wouldn't work...:eek:
  11. AlexRichter Guest

    Jun 25, 2009
    Its a pulsing/strobing. It happens at low brightness levels and seems more apparent at high load. Oddly the Genius I spoke to originally admitted seeing it very clearly and said there was clearly an issue. He then went out back with the computer and came back and started blaming software I was running or that I had done something to my user account - neither of which are true as I tested a fresh install. I don't think its the same problem as the lime green that sounds like a faulty graphics card.
  12. panzer06 macrumors 68030


    Sep 23, 2006
    So true!
  13. jgo78 macrumors 6502

    Nov 11, 2008
    ok, yes it's the same problem i have with my older 15" uni, my new 17" doesn't have this problem. And that 'genius' has no idea as I've tried everything on my 15" and still same problem. If you see the explanation above, this person seems to know what the problem is. It seems like hit or miss in getting one that doesnt have this problem.

    Let us know if the logic board fixes the problem, thanks.
  14. AlexRichter Guest

    Jun 25, 2009
    Yeah, but I tried to explain that to the genius, but he treated me like an idiot, and was purely trying to convince me to live with it.

    I'm sure a logic board won't fix it... I've seen on the Apple discussion boards people who have had this done as well as replacing the display and neither have solved the issue. Not sure how to persuade them of this though.
  15. jgo78 macrumors 6502

    Nov 11, 2008
    i know, its seems a very tough problem to solve and that's why i have yet to take my 15" to get repaired to avoid this type of run-around. Shame when we paid so much money and clearly there's a problem and nobody has the answers except for maybe a few engineers.
  16. iLog.Genius macrumors 601


    Feb 24, 2009
    Toronto, Ontario
    Does it happen in just the application window or is it the whole screen (so you'll even see the dock or menu bar do the same)?
  17. jgo78 macrumors 6502

    Nov 11, 2008
    its the whole screen, the backlight strobes in and out very quickly but subtely, more noticeable on 'lighter' backgrounds.
  18. Edwardish thread starter macrumors newbie

    Aug 28, 2008
    Yes exactly its what happening to mine.... its like flash lights... blinking
  19. AlexRichter Guest

    Jun 25, 2009
    Just an update so you guys know how its going. I have just gotten a call from the Apple store to let me know the repairs are complete. I am going to test the laptop in store so as to not waste a journey. Its now had two repairs but if its still not fixed I think I am going to push for a replacement.
  20. AlexRichter Guest

    Jun 25, 2009
    Sorry for double post but just got back from the Apple store.

    Firstly the logic board replacement did NOT fix the issue, it made no difference whatsoever. So I immediately asked to book it back in for repair. This time I got to speak to the engineer who did the repair rather than a genius which was a breath of fresh air.

    He basically agreed it was an issue but was unsure what else would fix it apart from a logic board replacement. But he wanted to try replacing the screen even though he thought this would be a pointless venture (he seemed very anti a replacement).

    So that's where I am at, at the moment... getting the clamshell replaced.
  21. GodWhomIsMike macrumors 6502a

    Sep 24, 2007
    Ouch, and to think, I just got off the phone with Apple trying to buy a refurbished model of this laptop. They were out of stock, and after reading this thread, that was probably a very good thing.
  22. nilblank macrumors newbie

    Jun 21, 2009
    I just had my (less than a month old and purchased just before the mid-2009s hit the street) 15" 2.66 MBP repaired to deal with this issue.

    They replaced the logic board. But the pulsing persists. Really extremely unimpressed. Not one of the other laptops I have owned has ever caused me physical discomfort to use.
  23. AlexRichter Guest

    Jun 25, 2009
    Have you tried a second repair since the logic board replacement?
  24. jamesryanbell macrumors 68020


    Mar 17, 2009
    Me. Starting happening about a month ago. Early '09 MBP in my sig.
  25. macdudechafic macrumors newbie


    Nov 7, 2009
    Beirut, Lebanon

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