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Model A1311 / Mid 2010 / 3.06 & 3.2 GHz Core i3 or 3.6 GHz Core i5 Processor

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iMac, crazy fans and no screen!

Hi all,

First post here looking for some help.

I've been given iMac by a family member due to it not working. It looks like someone has opened it before, as the cable to screen have been damaged :-(

However the iMac turns on but the screen is black. It chimes,as usual hard drive and everything boots up, but no picture. After about 10 seconds the fans go into mega overdrive.

I've plugged it into an external monitor and the screen appears fine on there. But it doesn't boot to anything just hangs.

I've tried resetting the PRAM I think it is, no change.

I've even tried holding down D upon startup, but the fans are going so mad I don't want to damage it further. Any ideas what this could be so I could order a part to fix it. I was hoping this could diagnose what the fault would be

Any advice would be greatly appreciated.

Thanks,

James.

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Asle,

Thanks for the quick reply. I've opened up the iMac got the LCD off fully now. When I opened up the iMac the LCD was just literally put back in with screws, and all the cables disconnected, so someone had obviously thought, i'll just throw it back on.

Currently I have it connected to external monitor, with the LCD totally disconnected. Looking at that guide, and the back of the LCD is appears that the person has ripped off the LCD thermal sensor cable. Everything else on the Mac, appears to be plugged in perfectly. Regarding the 4 LED lights, 1,2,3 all light up. The number 4 doesn't light up at all.

Obviously this is all done, with the SCD screen unattached.

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What model is this? You can check with the serial number on the bottom of the foot. Go to this page and choose "Browse by product" and enter your serial number.

If someone has opened it and you say the the screen cable (LVDS) was damaged, it seems it maybe was not inserted correctly on the logic board side. Also it could be damaged again inserting it incorrectly. If you can open the iMac and tilt the screen so you can see the 4 LED lights beside the LVDS connector you can tell us what light are on. LED 1, 2 and 3 should light up. Then LED 4 should light up and then off.

The crazy fan blowing indicates that a cable is not attached correctly, maybe the temp sensor to the hard drive or LCD. Take a look at this guide and check that all the cables are attached. Could be going over the cables again could solve your problem.

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crwdns2944067:02crwdne2944067:0:

Asle, Thanks for the quick reply. I've opened up the iMac got the LCD off fully now. When I opened up the iMac the LCD was just literally put back in with screws, and all the cables disconnected, so someone had obviously thought, i'll just throw it back on. Currently I have it connected to external monitor, with the LCD totally disconnected. Looking at that guide, and the back of the LCD is appears that the person has ripped off the LCD thermal sensor cable. Everything else on the Mac, appears to be plugged in perfectly. Regarding the 4 LED lights, 1,2,3 all light up. The number 4 doesn't light up at all. Obviously this is all done, with the SCD screen unattached.

I've checked serial number it is a Late 210, 21.5"

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So the ripped off LCD thermal sensor (or any thermal sensor cable) is causing the blowing. Do you mean the connector is ripped off or only the cable? So you need to get the cable fixed. As long as the pins are not broken on the logic board you could get a new cable. How does the LVDS connector on the logic board look, and the LVDS cable? You can get all those cables from aliexpress. In fact I have the same machine as you (in my apple-museum!) I also have a black LCD but first I had the crazy fan blowing. I took out the logic board and went over all the cables. Also bought a new LVDS cable. It is now starting up fine, no fans blowing. But the screen is still black. I still have to find out what LED 4 really means. I have the same problem. It does not light up. I read it should light up, then go off. Maybe for you it is checking the thermal cables and then just fails.

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