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Model A1311 / Late 2009 / 3.06 or 3.33 GHz Core 2 Duo processor

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Stuck on white screen at startup

Hey. I have this older machine, which remains white screen under start up. I have tried several key combinations, just without luck. I have therefore opened the machine to backup the hdd. It succeeded but often "lost" my own Macbook connection to the Imac's hdd. That's why I thought it might be a hdd error. But before I buy a new hdd would I hear if there were other advice? Can also see this component on the motherboard look a little burned?

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The logic board does show some tarnish on the exposed copper of the XDP connector pads (used at the factory). I do see some tarnish on the lower areas of the pads use a soft paint brush to loosen the dust and a can of can'ed air to blow away the dust. Then use a cotton swab with some copper tarnish cleaner (liquid) to clean the area. Don't let the cleaner drip into the system or through the holes of the board. Then wash the area with distilled water in the same way making sure it too doesn't travel.

Then post another picture of the area.

par

I’m suspecting the SATA to USB adapter or case you used did not offer external power. The 3.5” drives need more power than what your laptop can offer via the USB port. Thats why you kept loosing the connection.

Your backup may not be complete or have errors so be careful!

par

Hey. Thanks for reply. I use an external power supply to supply the hdd so it should not be the problem. But yes, otherwise you were right that a laptop would not supply enough power.

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With the HDD mounted back inside locate the four onboard diagnostic LED’s on the bottom edge on the right. A piece of black tape covers them. You should see the first three LED’s lit the fours won’t be as the display is not connected.

Here's a breakdown of the onboard diagnostic LED's:

  • 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.

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Thank you for all the advice. I have now found these three LED's. At mine, there are only three? And in these three there is light.

par

Thats OK some only had three LED's.

One last test to be sure do you have an external monitor you can plug in? I'm suspecting the display its self (T-CON board on it) is bad. But before you jump on replacing it do the last test to be sure.

par

I have now tried to connect Imac to my Cinema, and nothing happens here. The screen does not get any picture at all, only black.

par

Not good ;-{

Are you sure the display and cable are working? If they are then the logic board is bad.

Your system has a combo PCH & GPU chip (NVIDIA MCP7A)

par

Yes the screen works, just tested it with my Macbook. Is this why no key combinations work, besides NVRAM / PRAM?

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Kevin Christensen sera éternellement reconnaissant.
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