Screen flicker on LCD at dimmest setting?

Discussion in 'Laptop Hardware' started by DarrenHD, Aug 12, 2008.

  1. DarrenHD

    Ddragonwarrior

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    Yea, mine was set at Portable/laptop.

    I returned mine because i went through three, all of them had this issue. The second one had an entire column of dead pixels, (800 dead pixels in total). Horrible experience.
     
    Ddragonwarrior, Aug 30, 2008
    #41
  2. DarrenHD

    brachiopod

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    My machine has the problem as did the one on display at best buy. I really need the lowest brightness setting. Even that is actually too bright for my subdued lighting location where I usually use the One, very annoying. A BIOS that just locks out the lowest brightness setting will be garbage and really really stupid, an insult to Acer customers. You can go into the intel chip driver setup program and change the brightness there, but there are very course steps. Maybe I could get a sheet of neutral colored acetate to put over the screen... stupid. This does look like a hardware problem with the power supply though, I am guessing that they will not be able to fix this in BIOS; they need a bigger capacitor somewhere.
     
    brachiopod, Aug 30, 2008
    #42
  3. DarrenHD

    emilb

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    I agree that remove the lowest settings is a very bad ideea. I use too my AA1 in low light conditions.
    Checking the 5V on USB using an Osciloscope I've found there is a 100mV voltage drop when accesing HDD. If the HDD is the problem...
    It seems the HDD to be the problem. Maybe some capacitors on the 5V line on the HDD or on the Backlight controller power lines will solve this problem.
    But I don't want to open my AA1...regarding lots of troubles...maybe I'll need waranty...
    Maybe someone that opened the case of the AA1 and with good electronics knowledge can make some tests...
     
    emilb, Sep 1, 2008
    #43
  4. DarrenHD

    kiroptra

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    Within an hour of receiving my AA1 (xp, 6 cell), I got occasional screen flicker and then the LCD backlight went out on the entire left side of the screen. The only light was coming from the upper right corner of the screen, which lit the screen brightly there and dimly everywhere else. After a few seconds or minutes the entire screen would be backlit again. This happened at all screen power settings and both while on battery and when plugged in. And then, a few seconds or minutes later the problem would recur.
    Strangely, the problem disappeared (except for occasional screen flicker) the second day and only reappeared once on the fourth day of using it (today).

    I wonder if this is being caused by the same problem causing the screen flicker problem? I don't want to open the case to check to see if the video card is seated properly because it looks like I will probably need to do a return and don't want to do anything now that might void my warranty.
    If I had control of turning on and off the backlight by screen area, this would actually be a pretty nice feature, assuming that it lowered battery consumption. Not nice when it happens randomly and beyond my control though.
     
    kiroptra, Sep 2, 2008
    #44
  5. DarrenHD

    jalpert

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    I know there was at least one person with a couple of these machines, 1 which had the flicker, 1 that didn't. Did you try switching the batteries between the two? Maybe it's not a computer issue at all but defective batteries?
     
    jalpert, Sep 6, 2008
    #45
  6. DarrenHD

    bugmenot

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    I bought from Currys , UK , 2 dayz ago.
    HDD model, flickers.
    Also when it "sleeps" I can see a faint backlight under the camera area...

    Should I return?
     
    bugmenot, Sep 10, 2008
    #46
  7. DarrenHD

    univega

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    I had this problem too, but this issue is now fixed with the latest bios update. It removes some of the lower brightness settings.
    No problems since. :D
     
    univega, Sep 19, 2008
    #47
  8. DarrenHD

    brachiopod

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    More like hidden, not fixed. You could have set the brightness to the higher level before yourself. Now you have no choice.
     
    brachiopod, Sep 19, 2008
    #48
  9. DarrenHD

    univega

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    True, but it works for me. If the lowest settings flicker I don't want them.
    The brightness is still flexible enough after the update IMO.
    The bios password fix is a boost, that was a pain..
     
    univega, Sep 20, 2008
    #49
  10. DarrenHD

    Ddragonwarrior

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    I think its just a battery issue. I actually managed to find a friend's aspire one that didnt have this issue. Soon, i'm going to swap my battery with his to test.
     
    Ddragonwarrior, Sep 23, 2008
    #50
  11. DarrenHD

    Daijoubu

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    What? AHCI improve performance!

    I installed a Patriot Warp v.2 32GB SSD unit into my A150 and the speed isn't as good as it's supposed to be...

    Difference of 27MB/s...
     
    Daijoubu, Sep 23, 2008
    #51
  12. DarrenHD

    jalpert

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    I think this could very well be the issue, keep us posted.
     
    jalpert, Sep 24, 2008
    #52
  13. DarrenHD

    emilb

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    Some new researsh on the screen flicker problem...

    I've disassembled my AA1 and I've tried to pus some capacitors to reduce the screen flicker....But not succes...The 5V supply is the problem...the 5V supply has a voltage about 5.12 V when screen dimmed and no HDD activities. Its voltage drops depending on the load to 4.9 V. Using osciloscope I've seen there not the output capacitor is the problem but the supply IC itself. The voltage drop is not a glitch, it depends on load. The supply IC do not have good load stability. I've found that the supply IC is the PU7, near the RAM socket, and in my board is somthing as RT8206, if I remember well...Looking at pictures posted by other users I've found thet on their AA1 the supply IC is ISL6237. So, the screen flicker may depends on what supply IC we have on our mainboard on AA1.

    Please, everybody who disassembled the AA1 tell what Supply IC you have and how the screen flicker is.

    A link to a picture with ISL6237:
    http://picasaweb.google.com/FFurcas/AA1 ... 6814899218

    Thak you and I hope will solve the flicker problem, that Acer is not able to do...without remove the low dimming settings. I hate that.
     
    emilb, Oct 4, 2008
    #53
  14. DarrenHD

    UncleDim

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    5.12->5.0 voltage drop is documented (see datasheet, fig.8)
    when IC is operating in "SKIP" mode. There is no such drop in fixed PWM mode (but less efficiency when idle or light load condition), may be switching to PWM (not constantly, only for the time when display is on) will solve the problem without affecting battery life.
     
    UncleDim, Oct 5, 2008
    #54
  15. DarrenHD

    emilb

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    Nice find UncleDim. I've seen now how the IC work. I believed the problem is with the chip. Disabling the SKIP mode will increase the Idle current, but if we have lowest dim settings disabled will increase the current for backlight. If we can disable the SKIP functionality maybe we solve the screen flicker. And I'll like that.
    Now we must see if we can cut the conection to GND from the SKIP pin and conect it to VCC. I think this is the hardest thing. And also we need to see if the IC will work with current inductor value.

    Thank you for the info.
     
    emilb, Oct 5, 2008
    #55
  16. DarrenHD

    UncleDim

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    Unfortunately no. I've just tried that. BTW, I have RT8206B too.
     
    UncleDim, Oct 5, 2008
    #56
  17. DarrenHD

    emilb

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    Did you find the datasheet for RT8206B? My search was not succesfull.
    Thanks.
     
    emilb, Oct 6, 2008
    #57
  18. DarrenHD

    UncleDim

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    My too.
    But board revision/assembly seems to be the same for ISL and RT.
     
    UncleDim, Oct 6, 2008
    #58
  19. DarrenHD

    emilb

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    UncleDim,

    You told me that the trying to disable SKIP functionality and does nothing. Is there any change in backlight flicker? You checked the power voltage with an ther function osciloscope, is there any improvment? Maybe the RT8206 does not have any other mode than SKIP...While we don't have the datasheet we only assume that chip is full compatible with ISL6237.
    I'll try to find some pictures with MSI Wind or EEEPC to see how power supply is implemented. Those noteboks do not have the flicker problem...or use other way to control the screen backlight.
     
    emilb, Oct 6, 2008
    #59
  20. DarrenHD

    UncleDim

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    Little less flickering, but it still present..
    Tried Ultrasonic SKIP mode too, flickering increased dramatically:)
    Haven't check with oscilloscope yet, but i'll try at weekend.
     
    UncleDim, Oct 8, 2008
    #60
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