Help! Display Blank After Home Repair!

Juicy-Tomato

macrumors newbie
Original poster
May 26, 2013
3
0
Hi everyone

So intelligent me decided to get my 2008 24" iMac out and replace the hard drive with a new one. Money's tight at the moment and I didn't feel like paying a couple of hundred dollars to get it installed. How hard could it be?

So I downloaded a copy of an official Apple service manual for the same model iMac. I followed the instructions perfectly, and installed the new hard drive with no hassles.

I put it all back together (following the service manual instructions) and it came time to turn it on. When I turned it back on there was nothing on the display. It was blank.

I took off the aluminum bit to see what the diagnostic LEDs had to say. When I turn it on LED 1 & 2 turn on and that's all. Now the CPU fan turns on like normal, but after about 30-40 seconds it starts spinning at full speed. I'm finding this rather irritating and I don't feel like pulling the graphics card to bits. If that;s what needs to be done so be it...

Any help or advice would be great cause I'm starting to get sick of using a PC.

Cheers

Stu :)
 

justperry

macrumors G4
Aug 10, 2007
10,175
5,319
Home is everywhere and nowhere.
iFixit says this on the Leds:

iMac Intel 24" EMC 2134 and 2211 Diagnostic LED's

To observe the LED's you need to apply power to the iMac with the front bezel off. Please ensure you don't touch any part of the iMac or the exposed circuit boards while you have power connected.
Locate the Diagnostic LED's between the RAM slots and the SATA connector.
The LED's are numbered 1-4 from left to right. You may need to move the SATA cable to get a clear view of the LED's.
If you are using this guide for iMac Intel 20" EMC 2210 and 2133 the LED's are located above the SATA connector and not as visible.

LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.
Technique: iMac Intel 24" EMC 2134 and 2211 Diagnostic LED's

Seems to me the Display and/or the GPU is somehow not connected correctly.

Here is the iFixit page on replacing the HD:

iMac Intel 24" EMC 2134 and 2211 Hard Drive Replacement

Edit: Step 7 in the last link could be a possibility.
I would check all connectors again.
 

Juicy-Tomato

macrumors newbie
Original poster
May 26, 2013
3
0
Hi there justperry,

Thanks for that, I wish I saw this about 3 days ago hehe. I'll have a go at it right now and get back to you to see if that has done the trick.

Thanks for that :)
 

Juicy-Tomato

macrumors newbie
Original poster
May 26, 2013
3
0
Hey justperry

I finally found some time to go ahead and try out the guides you suggest, but of course to no avail.

What I have done is following the service manual closely I have removed the logic board and video card and re-clipped the graphics card into the logic board. I reattached logic board and put all the plugs back in the correct order and I am still having the same issue.

I then went on and performed an SMC reset which of course did nothing, the CPU fan still spins at full speed after approximately 30-40 seconds after startup.

In regards to the diagnostic LED's I get the usual LED 1 & 2 lighting up upon startup, but I did notice that LED 3 comes on for about a second and then turns off, any ideas? or have a well and truly stuffed the poor thing up?