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

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Black screen now, after switching from 220V to 120V

I recently moved from EU to USA, and I brought my 2009 iMac 21.5" with me. I learned that input voltage is fine over the entire 100-240V range, so I simply put an adapter on the power plug and plugged it in to an American (120V) socket. Computer ran fine before the flight, but not now.

I hear the initial chime, and I do see some response in the screen brightness (perhaps the backlight is working?), in that the whole screen changes from completely black (the OFF state) to a slightly lighter gray. I can't really proceed from there, because I cannot see anything on the screen. Even with a flashlight, I cannot see the login screen.

Could it be that the input voltage isn't sufficient to run the display, somehow? Should I buy a voltage transformer (120-->220) and test it? Or is the timing merely a coincidence, and I probably have some "normal" display problem (which are discussed in other threads)?

Thanks in advance for any help!

Update (07/08/2017)

Just to update: I removed the front panel and LCD, and the "first four" cables: vertical sync, LCD inverter cable, temperature sensor, and LCD data cable. I check other visible cable connections and re-seated some of them. When I turned it on, everything worked fine! Was very happy to see the Apple logo! Thanks everyone for your advice, I didn't even need to find an external monitor, or anything else. Was an ideal fix, only cost me $2 for the suction cups to remove the front panel.

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Here's the specs of your system: iMac 21.5" 3.33 GHz Core 2 Duo (Late 2009)

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@jgjuus reset SMC and PRAM to clear any stored, corrupted information. start with this!

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You don't need any power conversion here as your system has a 120V-240V 241W power supply.

What more likely happened here is the shipping bounced the system a bit. So something loosed up (cable connection) or either the display or graphics logic have failed on you.

To isolate if the GPU its self has failed or if the cable that connects the display to the logic board disconnected you'll need to plug in an external display.

If the external shows an image then you know your internal display connection or the display its self is in trouble. If the external still won't show an image then your logic board needs repair or replacing.

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What are the diagnostic LEDs to the right of the RAM slots telling you?

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@mayer Do I need to remove the RAM to access these?

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Ok, I read how to tear down to access these diagnostic LEDs. First I will try an external monitor for simplicity, and then based on what I find (or don't), I will then start planning to disassemble.

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@jguus here are the diagnostic LED's @mayer is referring to.

Block Image

Block Image

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

Resetting the System Management Controller (SMC)

The System Management Controller (SMC) is a chip on logic board that controls all power functions. If computer is experiencing any power issue, such as not starting up, not displaying video, sleep issues, or fan noise issues, resetting SMC may resolve it. To reset SMC on an iMac:

1. From Apple menu, choose Shut Down (or if the computer is not responding, hold power button for approximately ten seconds until it powers off).

2. Unplug all cables from computer, including power cord.

3. Press and hold the power button for 5 seconds.

4. Release the power button.

5. Attach the computer’s power cable, making sure power button is not being pressed.

Note: If you press the power button while inserting the power cord, the iMac will enter a mode in which the fans run at full speed.

6. Press the power button to turn on the computer.

Resetting Parameter RAM (PRAM)

PRAM stores certain system and device settings in a location that Mac OS X can access quickly. Exactly which settings are stored in the computer’s PRAM varies depending on the type of computer as well as the types of devices and drives connected. To reset PRAM:

1. Shut down the computer.

2. Locate the following keys on keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in Step 4.

Note: If the keyboard does not have an Option key, use the Alt key instead.

3. Press power button.

4. Immediately press and hold Command-Option-P-R keys.

Important: You must press this key combination before the gray screen appears.

5. Hold down keys until the computer restarts, and you hear the startup chime a second time.

6. Release keys.

Symptoms

Won’t Start Up

• No startup chime.

• Error tones during startup.

• Grey screen with fan noise, or other noise.

• Will not progress beyond Apple logo or spinning gear.

Quick Check

1. Isolate OS by starting up from original install media for this computer, from a same-model computer in Target Disk Mode, or from a compatible known-good OS on an external drive. Both AirPort and Bluetooth services are available when booted from the Install disc.

2. Reset SMC and PRAM to clear any stored, corrupted information. start with this!

3. Start up in Safe Mode by holding shift key down during startup to load only required kernel extensions and disable all startup and login items. See kBase #HT1564: Mac OS X: What is Safe Boot, Safe Mode?

4. If system generates error tones there may be an issue with the SDRAM. See kBase #HT2341: Intelbased

Mac: Power On Self Test RAM error codes

5. Identifying when in the startup process the computer hangs can help isolate the issue. See kBase #HT2674: Intel-based Mac: Startup sequence and error codes, symbols for information on the Macintosh startup sequence, and error codes and symbols used.

Deep Dive

1. Boot computer to Apple Hardware Test on the internal hard drive or an inserted Install DVD by holding down the D key at startup. Verify if system boots up from any of these volumes.

Yes

Run the extended tests and proceed with results. If AHT passes or boots with a memory error, go to step 2.

No

Go to step 2.

2. Remove installed SDRAM, and test with known-good SDRAM. Verify if computer starts up properly now.

Yes

SDRAM issue. Reinstall one of user’s SDRAM modules and retest. Proceed one by one to find the faulty SDRAM module, and replace it.

No

Go to step 3.

3. Wait 15 seconds after computer was powered down and disconnect AirPort cable from logic board. Verify if computer starts up properly now.

Yes

Go to AirPort Card Kernel Panic symptom flow.

No

Go to step 4.

4. Disconnect hard drive SATA cable and startup from Install DVD in the optical drive, or from an external bootable volume. Verify if computer starts up properly now.

Yes

Go to Hard Drive Not Recognized symptom flow.

No

Go to step 5.

5. Reconnect hard drive, disconnect optical drive cable and retest. Verify if computer starts up properly now.

Yes

Go to Optical Drive Not Recognized symptom flow.

No

Go to step 6.

6. Remove coin battery on back of logic board (you will need to completely remove logic board to do this), and leave out for approximately 1 minute. Then reinstall battery. This will reset logic board. Verify if computer starts up properly now.

Yes

Issue resolved by logic board reset. Measure DC voltage on battery touching battery with red probe, and grounding with black probe. If voltage is 2.7v or less, replace battery.

No Replace logic board. (Hold off on that for now)

Once you've tried all this, let us know what you get.

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I inspected the diagnostic LEDs, and only #1 and #2 are on. Does this now eliminate the need to test whether an external monitor works?

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@jgjuus - Sadly this implies the GPU logic on the logic board has failed. This model doesn't have LED3 only LED1, LED2 & LED4 as it has an intergraded GPU. Here's the P/N's for your system

- Logic board 3.06 GHz - 661-5305

- Logic board 3.33 GHz - 661-5306

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@jgjuus no it does not. You still want to connect an external monitor. The reason for that is based on the diagnsotic LED's:

If fourth LED (remember you do not have #3) 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

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@oldturkey03 I did this, and no change. Only the LEDs #1 and #2 are lit on startup.

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