what is most likely to fail on imac 2009 27 inch

Prepare the iMac not turning on problem pace-by-step

At that place are many potential reasons why your iMac won't turn on. The method you use to fix them will depend on how unresponsive your iMac is. Completely unresponsive iMacs such as no power at all may be hands fixed. Slightly responsive iMacs with fan spin noise may have more than circuitous issues related to the logic board.

The major divergence between an iMac and a MacBook is the bombardment. An iMac doesn't rely on battery power, therefore troubleshooting the "iMac won't turn on" trouble is easier than troubleshooting the "MacBook won't plough on" trouble. If yous take a MacBook problem, see our article MacBook Won't Turn On? 10 Ways To Fix It . If your iMac is stuck on the loading screen, see our article: What to do when your iMac stuck on loading screen?

Although the cause of your iMac not turning on can vary in each case, hither are steps to take when things do go incorrect:

1. Make sure your iMac is receiving power

This is a simple step, merely information technology is a height priority. Bank check if the ability cable is undamaged and securely plugged into your iMac and a working electrical outlet. If you're not sure about the outlet, examination it with a lamp or a mobile phone charger.

The power cord plug (the end connecting to the iMac) of the post-2012 iMac is different from the one-time cord of the pre-2012 iMac shown as below. If you use a wrong string, the plug may not exist inserted all the way down to the iMac power socket, resulting in no power coming from the cord and so your iMac won't power on.

If you suspect your iMac power cord, use a standard PC power cord to exam. They are identical in terms of function.

two. Check for stuck ability button

If y'all have a viscous power button or a faulty power button, the ability button volition not be able to send a valid command indicate to the logic lath so your iMac will not turn on.

The pasty power button is caused by the dirt accumulated inside the button. iMac power push replacement is a time-consuming chore even for a Mac repair professional. Y'all demand to remove the iMac screen, the power supply and logic lath before you lot can get admission to the power push button. Luckily, virtually of the fourth dimension,  a failed iMac ability button is caused by dirt, not the electrical contact failure inside the power push button. You lot can hands remove the clay without replacing the button by following this procedure:

1. Unplug the power string to your iMac.
2. Put the iMac on a flat desktop with the screen facing down.
3. Apply 1 or two drops of WD-40 lubricant to the button. Let the liquid sink to the push.
4. Await for a few minutes until the lubricant softens the dirt.
5. Keep pushing and releasing the button to go the dirt out of the push.
6. Use a tissue to make clean the clay.
7. You may need to echo footstep iii to step five for a few times.

Information technology is a common misunderstanding that the iMac ability push button is operated at the main power voltage (110V Ac or 220-240V Air-conditioning). In fact, the iMac power button is operated at 3.3V DC and this voltage is pretty safety for human beings. Besides, the WD-40 lubricant is electrical friendly and not-conductive. Therefore the entire procedure is absolutely safe.

three. Check for any faulty external devices

If your Mac detects the accessories attached to it have brusque circuits or draw an unusual amount of current from the iMac, the iMac will not plow on. This is a safety mensurate to protect your iMac. You lot can easily dominion out if any device is the culprit.

Unplug all the accessories attached to your iMac including printer cablevision, network cable, firewire cable, USB hub, external USB hard drive and Mini display cable. It could be one of your peripherals causing your iMac not turning on.

4. Reset the SMC or T2 bit

The Organization Management Controller (SMC) is responsible for receiving power push signals, then starts and manages the entire power-on process. You may consider the SMC as a tiny figurer running a tiny operating system and the software sometimes could go wrong. If this happens to your iMac, you need to reset the SMC. Apple integrated the SMC scrap into the Apple T2 Security flake starting from 2018.

Resetting the SMC on an iMac is very simple, no matter if you lot have a stand-alone SMC scrap or T2 fleck.

1. Remove the power cable from the master socket.
2. Wait for 15 seconds, then plug the power cable back in.
3. Look for 5 seconds, and then press the power button to check if your iMac will turn on.

This method can be applied to Mac Mini, Mac Pro computers as they accept a single ability source (primary power). Mac laptops require a different approach as they accept dual power sources ( charger and battery). You can't easily disconnect the internal battery. If you desire to reset the SMC on a MacBook, see our article Reset SMC or T2 chip on MacBook.

If resetting SMC tin't solve the problem of iMac not powering on, try the next method.

five. Perform a power cycle

An iMac has three major states: Off , Slumber and On . Performing a power cycle ways you forcefulness the iMac returning to the off country.

If your iMac gets stuck in the Slumber state for some reasons, your iMac volition non respond to normal wake-up signals such equally pressing the keyboard keys or clicking the mouse button. Y'all need to force the iMac dorsum to the off country by performing a power cycle.

Unplug the power string from the main socket and wait for xv seconds so plug the power cable back in. At present you have forced the Mac returning to the off state. Printing the power button once more to see if your iMac can plow on.

half dozen. Check for signs of power

When y'all see nothing on the screen, you lot may call back that your Mac won't turn on. But that is not e'er the case. Your iMac may exist on already; but the screen is not working. Therefore, it is vital to double-check any signs of ability including sounds and lights to avert a misdiagnosis.

Check sounds in a repose environment: Do you hear a startup chinkle? If y'all do, your iMac is already on. Wait for 1 or ii minutes to check if there is any display on the screen. If you lot don't run across anything on the screen, your iMac most likely has a screen problem.

Put your hand near the fan vent holes at the back of your iMac. Do y'all experience any air coming from the vent holes? Practise you hear the fan spinning air noise, hard disk spinning dissonance, supper drive motor startup noise? Any of these signs point that your iMac has already powered on and there are other issues preventing your MacBook from working.

Next, cheque lights in a dark environment: If you don't encounter annihilation on the screen, shine a flashlight to the summit right-paw side corner on your iMac screen. If you can run into the dim text, press the screen "brightness up" button on the keyboard a few times to increase the screen brightness. If yous still go dim text, you accept a screen backlight problem. The screen backlight problem could be caused by a faulty screen or a faulty logic board.

Press the Caps Lock primal, if you lot can see the light on, your iMac is running. You may also have a screen problem.

Connect an external monitor to your iMac via a mini display port, thunderbolt port. If you have a brandish on the external monitor, y'all definitely have a faulty screen

seven. Check for a faulty RAM

If you hear repeating beeps from the iMac, your iMac could have RAM faults that are causing your iMac to not turn on.

If you hear one beep, repeating every five seconds, it ways your iMac tin't detect any RAM. If y'all recently replaced or upgraded the retentivity, check to see if it was installed properly.

If you get three successive beeps, then a 5-2nd interruption and keep repeating, your iMac RAM doesn't pass a data integrity cheque. If you recently replaced or upgraded your figurer'south RAM, cheque to see if it was installed properly. You too tin can attempt dissimilar make names of retention modules.

8. Restore corrupted T2 security scrap firmware

Starting in 2018, Apple integrated the SMC bit to a larger multifunctional chip called Apple T2 security chip in the new Macs. The T2 chip takes over the duty of SMC. If the T2 scrap is non functional, information technology won't respond to the power button and your iMac won't power on.

If you updated your iMac's macOS to one that contains a device firmware update (DFU) but failed to complete the whole process for some reason, you could end up with T2 chip firmware corruption. In other words, you may have bricked your iMac.

To fix a bricked iMac, you need a working host MacBook and download the firmware from Apple's website. So you force the bricked iMac into DFU mode so y'all can transfer the firmware to the bricked iMac via a USB-C cable.

1. Go to Apple'southward website to download the app Apple Configurator 2 . You may need to update to the latest macOS to run the app. Open the app and make sure your host MacBook is connected to the internet.
2. Unplug the power cord of your bricked iMac.
3. Utilise a standard USB-C cable. Connect one end to any port of your host MacBook.
4. Connect the other end of the USB-C cable to the master port of your bricked iMac. The master port is the USB-C port next to the Ethernet Port.
5. Press and hold the ability button. While holding the power push button, plug in the power cord of your iMac. Continue to concord the ability button for about 3-five seconds until you run into the DFU logo on the Host MacBook.
6. Release the ability button. Now your bricked iMac is in DFU manner.
7. Go dorsum to your host MacBook, click to select the DFU device on the screen and select Activity from the menu bar. On the pull-down menu bar select Accelerate and select Revive Device. Confirm the action.
8. At present the host MacBook will download the right firmware version from Apple'south server and install it to your bricked iMac. This may take up to 5 minutes.
9. Afterwards finishing the installation, your iMac will automatically power on. If you lot tin see the Apple logo, congratulations! Yous have successfully saved the bricked iMac.

9. Cheque for faulty iMac power supply

iMac ability supply failures account for the majority of dead iMacs. If you accept gone through all the checks discussed above and your iMac all the same doesn't turn on, you most likely have a failed power supply, especially if your iMac won't plow on afterward power outage.

To go access to the power supply, you need to remove the iMac screen. In the pre-2011 iMacs, Apple uses viii screws to adhere the screen to the iMac frame. In the post-2011 iMacs, Apple tree used double-sided sticky tapes to attach the screen to the iMac frame. Take extreme care when you remove the iMac screen as information technology is very easy to intermission the screen.

Unlike standard desktop PCs, the iMac power supply is NOT sealed in a protective metal box. The dangerous high voltage department is non covered every bit shown on the photo below.

You can encounter the measurement point has a very loftier voltage of 395.1V DC. All our technicians are required to wear protective gloves when they handle iMac hardware repairs. The gloves not just protect the technicians from accidentally touching the dangerous points merely also avoid leaving finger marks on the screen. The finger marks on the older iMac screen are non easy to remove.  Think, don't touch anything on the power supply unit while the ability unit is on.

Follow this procedure to check the iMac power supply:

1. Remove the power cable from the chief powerpoint.
2. Wait for at least 10 minutes until the big capacitors in the power supply have been completely discharged (from 395V to 0V).
3. Remove the iMac screen from its aluminium frame.
4. Plugin the power cable back to the main powerpoint.
5. Check for the four LED lights on the logic lath. If no LED light is on, y'all accept a faulty iMac power supply.

The four LED lights are diagnosis lights. It indicates the status of the iMac logic board. The commencement LED light indicates the logic board is in standby mode. If the power supply has no output, the iMac logic lath will not enter into standby mode, so the corresponding LED light will not turn on.

IT-Tech Online is a leading Mac repair specialist in Australia. We are more than happy to help you if yous cannot fix the problems yourself. We offer competitive prices for iMac repairs.  Please contact us. Our experienced staff will phone call you to assess your situation and provide a free quote for you lot.

10. Bank check for faulty iMac logic board

There are four diagnostic LED lights on every model of iMacs. The location of the LEDs varies in different models. The behaviour of the LED lights can tell you a lot of information.

1. S5 Led. It indicates the logic lath has received ability from the power supply and currently in standby style (technical term S5 country). In other words, the iMac is ready for you to push the push button to turn it on.
2. All_SYS_PWRGD Led. This is a technical term for "all system powers are good". When all the system powers including the CPU, RAM just excluding GPU are ok, this calorie-free will be on.
3. GPU GOOD Led. If the GPU has received power and passed the self-checking examination, this led lite volition turn on.
4. VIDEO ON led. When the GPU has detected an iMac screen connecting to the logic board, the GPU will turn on the backlight of the screen and the VIDEO ON led.  And then the GPU will output video signals to the screen.

Remove the iMac screen equally described higher up and plug in the power cord to the primary powerpoint. If the first LED light (standby lite) is on, push the iMac power button and follow the instructions beneath to diagnose the logic board.

1. Once you push the iMac power push button, the standby light goes off. This symptom indicates that the logic board has a shorted excursion. The shorted excursion draws an unusual amount of current from the power supply, therefore the power supply cut off output to protect itself.
2. When yous push the power push, the standby light remains on, the other three lights are off. This symptom indicates that the logic board is not responding to the power push. Double-bank check the iMac ability push button and make sure it is functional. If the power button is ok, then the logic board is faulty.
3. When you printing the button, simply two lights are on. This symptom indicates the graphics department of the logic board is faulty. Graphics carte du jour failures are very common for iMacs manufactured between 2007 to 2011.
4. If iii lights are on, your logic board most likely is ok. The error is on the iMac screen.

Please notation that the fourth LED calorie-free won't be on until yous connect the iMac screen to the logic lath.

If you accept a faulty iMac logic board, you may cull to repair or supervene upon the logic board. Apple stores and Apple tree Authorised Service Providers can only replace the logic board. Repairing the logic lath requires much higher knowledge and skills. A Mac repair specialist who does component-level repair can repair the logic lath at a fraction of the replacement price.

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Source: https://www.it-tech.com.au/imac-wont-turn-on/