replaced power supply and still dead. no sound. check line120v in.
how to troubleshoot computer. almost like the power button is not working.
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Tell us what the diagnostic lights are telling you.
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Where are the diagnostic LEDs located?
I opened the unit while changing the power supply and i didnt see any LED Lights. Where would i find them? This is a 2009 iMac EMC 2308
To the right of the RAM slots on the logic board.
Ok looking through the bottom ports, small holes, I see a solid green tiny light. Stays solid when I plug in the cord. Goes off about 15 seconds after pulling plug.
herb, there should be more than one light
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herb, this is just to help out with the LED's. For the rest you need to pay attention to @mayer
Diagnostic LEDs
Depending on iMac model, there are either three or four built-in diagnostic LEDs on the logic board that can help troubleshoot the computer. LEDs are located on bottom right edge of logic board (under a piece of black mylar tape) and can only be seen when looking through lower vents of rear housing.
LED Functions
LED #1
• Indicates that trickle voltage from power supply has been detected by logic board. This LED will remain ON whenever the iMac is connected to a working AC power source. The LED will remain on even when computer has been shut down or put to sleep. The LED will turn off only if AC power source is disconnected or power supply is faulty.
LED #2
• Indicates that logic board has detected power from power supply when computer is turned on. This LED will be ON when computer is turned on and power supply and voltage regulators are working correctly.
LED #3
• Indicates that computer and video card are communicating. This LED will be ON when computer is communicating properly with video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then video card might be installed incorrectly or need replacement. Note: LED #3 is not present on models with integrated graphics.
LED #4
• Indicates that computer and LCD panel are communicating. This LED will be ON when computer is turned on and video signal is being generated. If LED 4 is ON and there is no image on display, then LCD panel, LED backlight board, or cables between might be installed incorrectly or need replacement.
LED Startup Sequence
LED #1 = Power available.
If no LED is visible:
• Verify AC source
• Verify known-good AC cable is connected
• Verify cable connection between AC inlet and power supply
• Verify cable connection between power supply and logic board
• Verify power supply
LED #1 + LED #2 = Power available, and system is powered on.
If second LED is not visible when power button is pressed:
• Verify power button connection to logic board
• Verify power button functionality
• Verify cable connection between power supply and logic board
• Verify power supply
• Verify logic board
LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found.
If third LED is not visible after power on:
• Verify that MXM video card is seated properly
• Verify logic board
LED #1 + LED #2 + LED #3 + LED #4 = Power available, system is powered on, video card
found, and internal LCD found.
If fourth LED is not visible after power on:
• Verify cable connections between LCD panel and logic board
• Inspect LCD display cables for cable damage
• Verify external video functionality, and according to result check the following items:
-If external display works then verify/replace LED backlight board
-If external display works then verify/replace LCD panel
-If external display does not work verify/replace logic board
Let @mayer know what you find....:-)
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Thanks, I couldn't find any troubleshooting information on the 21.5 Intel iMac. Again thanks. And I will pay close attention to Mayer.
herb, before you accept an answer you should wait until you can determine which is the right one. Like I said, mine is just to assist mayer to assist you :-)
Thanks. Didnt know what to do. Accepted both answers as both you guys helped tremendously.
