iMessed up my iMac screen....

Discussion in 'iMac' started by chrisworld, Dec 26, 2009.

  1. chrisworld macrumors member

    Nov 14, 2006
    Update: Problem Resolved

    Thanks for your suggestions and help.

    I have been lazy, and I know from the HDD replacement and one open prior to that.. that it takes effort to open these cases...well not really, but its the part about removing and replacing the LCD unit and it's recessed screws.... Finally I decided to open it again and to my of the wire clusters was unplugged from it's circuit board. I knew it wasn't the HDD all along, as this thing hardly draws any more power then the old noisy one.

    I'll call them clusters, cant think of a better name right now...

    There are 5 wire clusters for the Backlight/LCD combo unit in the November 2006 model iMac. The main ribbon cable that supplies the LCD panel with picture, and 4 separate clusters of wires (for the backlight panel I presume).

    Two of these four for the backlight consist of just two wires each and another two consist of 5-6 or 7 wires each (don't remember exactly). One of the two-wire'd ones (the bottom one) was simply unplugged from that board I mentioned earlier. I'm guessing under that board is the transformer for the backlight power.

    This basically explains why the bottom part of my LCD wasn't as lit as the top..simply wasn't getting enough juice for that part. Why it started bright and then dimmed automatically (when it wasn't getting power there in the first place) is beyond me..but it is fixed now and back to the crisp 100% brightness it's has for 3+ years now.

    I have also heard of people receiving iMacs that come from the store or factory with dim areas on the LCD. I'd recommend this solution to anyone who has this problem as well. Its possible during manufacturing that a wire wasn't fully plugged in. Mine was of course my own fault; a simple overlook in a simple HDD replacement, not double checking that everything is seated/plugged in. But during manufacturing it's not impossible for them to make mistakes either.

    Orignal Post

    Well, I recently got that 750 GB HDD and installed it. I have taken my iMac apart once before to get dust out of the bottom fans which helped with overheating problems, but this time I dig slightly deeper to replace the HDD with this new bigger 750 GB. (The heat sensor part on the HDD was rather interesting)

    Now..I'm no barbarian when it comes to this machine, realizing how delicate it took me a good hour and a half at least with this machine making sure I was taking the utmost care when working inside if and removing the LCD panel.

    Well, it was all successful, I now have a huge chunk of digital world to put stuff on. But there was one small problem about 1 second after re-power up and just before reinstallation of Tiger (no leopard, i don't have it).

    The bottom of the screen isn't bright anymore!!!!

    You can see from this picture mostly the bottom left shows up as brownish yellow and washed out...taken from my 2nd gen LG Chocolate phone.

    Well, what do I do? I only ask this because I know the screen isn't busted, because when I power the thing up, the screen is at normal healthy brightness, then it jumps the brightness down in that corner/bottom of the screen automatically and just stays there unless I restart, and watch it repeat the same process..just goes back dim again.

    EDIT: If it helps some... I didn't have the patience last night to update OS X, and over the years of having this thing (since Nov 2006) I have noticed LOTS of firmware updates. Now, since I have reinstalled I have version 10.4.7 (I will update later) and I wonder if a problem with the firmware updates.not being updated has something to do with it? I mean... it does go bright, brighter to normal and then bam its dim again.
  2. Ecoh macrumors 6502a


    Oct 30, 2009
    Do you think maybe the drive is using more power and now the screen doesn't have enough to stay bright ? I no nothing about hardware, this is just a wild guess.
  3. Pachang macrumors regular

    Dec 17, 2009
    let us know how it goes. It sounds like something is wrong with the backlight.
    It could be the firmware. Get everything updated and you'll find out.
  4. chrisworld thread starter macrumors member

    Nov 14, 2006
    Hey guys. I got everything all updated to the best of my knowledge and still goes from normal bright at initial start up (or after wakeups) and then to automatic bottom dim/washout right after. At a loss here. Maybe I'll open her up some other time and look at all those cords. There were about 4 cords going into one board and one long ribbon cable going into another. Im assuming power and data and all that.

    I never considered the HDD messing with the power because my old HDD was much more rugged and loud, this new ones is still a western digital but its a "green power" and it is a LOT more quiet so I assumed it's not taking that much more power then the old one.

    I'd really like to regain full brightness, it's not a huge requirement but i'd just like it to be bright again. Keep in mind this happened in-between the time I replaced the either I messed hardware up or something else is wrong. I'd hate to think that after 3 years of hard use that its just going bad and its a coincidence. I don't know... I'll leave it alone and see if it fixes itself on it's own and when I get the time to I'll crack her open again and play with the cords. It's just such a mofo trying to remove the the LCD screens in these things.
  5. MacHamster68 macrumors 68040


    Sep 17, 2009
    its easy to check if the harddrive is the cause of the dimming , just reverse and fit the original again, if its ok after you know its the harddrive causing the problem ,
    ok i never heard of such thing ,but then the iMac `s psu isn`t the most powerful in the world ~180watt i think if i`m right ,so i would not rule out the harddrive as some use a bit more power then others the range is i think about between 5 watt and 15 watt ,
    i know that does not sound much but its not the only component that drains power in the imac , there is the cpu , the optical drive , the logic board , fans and of course the lcd screen takes some power too....

    so if the harddrive is causing it , then every other attempt to solve the dimming problem will be a waste of time ,so your first target is to rule out the harddrive
  6. chrisworld thread starter macrumors member

    Nov 14, 2006
    I'm really not positive I'm going to swap HDD's again, the space bonus, the fact my iPod touch gets more use on music/browser/email and its not noticeable in games is much greater then the screen being bummed out but I'm still opening it just to get to the LCD wires.
  7. cjmillsnun macrumors 68020

    Aug 28, 2009
    My guess is a loose connection to the LCD inverter, or a faulty inverter. It used to be a common problem on 17" Studio displays.
  8. Badger^2 macrumors 68000


    Oct 29, 2009

    Impossible. Forget that idea as a possibility.
  9. chrisworld thread starter macrumors member

    Nov 14, 2006

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