How to get around Broken LCD Temperature Sensor? Slow or stop FANS?

Discussion in 'iMac' started by meagain, Aug 4, 2012.

  1. meagain, Aug 4, 2012
    Last edited: Aug 6, 2012

    meagain macrumors 68030

    Joined:
    Nov 18, 2006
    #1
    My port on the board for the LCD temp sensor is broken. Fans are going nuts. The instant I turn on the iMac.

    Does anyone know how to get around this? HDD fan control doesn't do anything.

    iStat says…
    Optical 3317 rpm
    Hard Drive 1116 rpm
    CPU Fan 4061 rpm

    Damn. Noisy as hell. The 'port' is broken not the cable so I guess the whole logic board is toast. Any ideas?
     
  2. meagain thread starter macrumors 68030

    Joined:
    Nov 18, 2006
    #2
    Conversely, does anyone know a way to turn off the fans? I'm not sure which one is making the most noise (cpu or optical), but it's really loud. I was hoping I could just quell them somehow but I don't see a way.

    Not sure what to do. Any help would be appreciated.
     
  3. R.OG macrumors regular

    Joined:
    Aug 19, 2010
    #3
    Are the solder pads intact? if so, you can always solder the wires directly to the pads.
     
  4. meagain thread starter macrumors 68030

    Joined:
    Nov 18, 2006
    #4
    Not sure what you mean by pads. The piece on the board is a 2 prong thingy the LCD temperature sensor wire attaches to. This thing is now missing its 2 prongs and so the cable plug has nothing to attach to.

    IDK if I can buy a new 'port' thingy to mount to the main board? Or if I can bypass something. But if not, I'm looking at at least $600-1200 for a new logic board?

    Mostly for now, my main goal is to make the fans shut up. It's like an airplane taking off. Do you know if I can do some type of command in Terminal or something? I guess I could unplug one and see how it goes.

    They are roaring and I want them to slow for now. As far as soldering this… I really don't know what to do so unless there's a youtube on it (likely not)… I'd be a bit lost on that. :(
     
  5. meagain thread starter macrumors 68030

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    Nov 18, 2006
    #5
    It doesn't seem SMC Fan Control has any effect on anything. Unless I'm doing it wrong. But I'm not sure why it wouldn't.
     
  6. jji7skyline macrumors 6502

    jji7skyline

    Joined:
    Aug 10, 2011
    #6
    That's because SMC fan control only controls the base fan speed. Try a different utility.
     
  7. meagain thread starter macrumors 68030

    Joined:
    Nov 18, 2006
    #7
    Well, that's what I'm asking and why I posted. What utility? I have HDD fan control and that doesn't do anything because it just deals with the hard drive.

    I can't find anything to tone down the CPU fan and Optical fan.

    Can't find any posted Applescripts around either.
     
  8. senseless macrumors 68000

    senseless

    Joined:
    Apr 23, 2008
    Location:
    Pennsylvania, USA
    #8
    Right. The lcd sensor connector is just 2 wires and should be easy enough for a tech to do. Break the display connector and you're screwed.
     
  9. meagain thread starter macrumors 68030

    Joined:
    Nov 18, 2006
    #9
    but if the wire is directly soldered to the board, then there would be no way to take the iMac apart in the future. Ideally, getting the 'port' thing that is attached to the logic board replaced and put back to where the cable can be plugged in again would be the way to go, but IDK what that part is or how to find someone to do that even if it's possible?

    I can't find anyway to turn down these fans so I'm taking it in to Apple today and my endeavor to clean my internal display rendered me with a clean screen and a broken logic board. :|

    I'm convinced some of these cables like that skinny ribbon one, degrade somehow.
     
  10. senseless macrumors 68000

    senseless

    Joined:
    Apr 23, 2008
    Location:
    Pennsylvania, USA
    #10
    You can still solder the wires directly to the board and put a molex connector on the wires so it could be taken apart.
     
  11. PigeonF16 macrumors newbie

    Joined:
    Sep 6, 2016
    #11

    Did you ever get this fixed? I have the exact same problem. HDD fan is 1100. CPU and ODD fans are around 3600-3900 whole time. The LCD Thermal sensor cable is barely hanging on the broken port on the logic board. I kinda knew I did it when I installed a HDD a year ago, but I was able to connect it. It worked until recently, and I'm sure it's lost contact.

    Any advice or solution would be appreciated.
     
  12. senseless macrumors 68000

    senseless

    Joined:
    Apr 23, 2008
    Location:
    Pennsylvania, USA
    #12
    I didn't actually do this; just commenting. The Original Poster never wrapped up the thread.
     
  13. PigeonF16 macrumors newbie

    Joined:
    Sep 6, 2016
    #13
    I cracked it open again and reset the LCD Thermal sensor on the logic board, which fixed the fan problem. I think I was too gentle connecting it the first time, and it barely made contact. Over time, it worked itself loose. The connecting pins are still there, but the plastic socket that you plug into is broken. Regardless, I just pushed it in a little more and it made definite contact. The fans run normally now.

    BTW, the root cause of my problems is the reinstall of the screen after replacing the hard drives. The solution is to have something to hold the iMac screen/stand fixed in place while reinstalling. The 27" iMac is a little unbalanced on its stand. I used iFixit's guide to replace the HDD and install a second SSD. When I got to the last few steps of placing the LCD and connecting the last few cables, the iMac rotated forward flipping the LCD out and onto the table. The two cables I had connected broke off the female ports. The cables stayed intact, but the plastic port on the logic board for the LCD thermal cable broke. I used pliers to straighten the two copper pins and reconnected it. One other cable had no problems reconnecting, but its female plastic port is missing a section (it reconnected no problem...just missing a piece of plastic). Since this isn't a laptop and won't move around much, I don't anticipate future problems (until I need to crack it open again). I think this last reconnection of the LCD thermal cable will hold...at least until I need to replace the iMac. Let's hope so.
     

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