Fix the iMac non turning on problem step-past-step
There are many potential reasons why your iMac won’t turn on. The method you utilize to fix them will depend on how unresponsive your iMac is.
Completely unresponsive iMacs such as no power at all may exist easily fixed. Slightly responsive iMacs with fan spin noise may have more complex issues related to the logic board.
The major divergence betwixt an iMac and a MacBook is the battery. An iMac doesn’t rely on battery power, therefore troubleshooting the “iMac won’t turn on” problem is easier than troubleshooting the “MacBook won’t turn on” problem. If you take a MacBook problem, see our commodity
MacBook Won’t Plough 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, here are steps to take when things do go wrong:
ane. Make sure your iMac is receiving power
This is a simple footstep, but it is a height priority. Check if the ability cable is undamaged and securely plugged into your iMac and a working electrical outlet. If you’re not sure most the outlet, test 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 erstwhile cord of the pre-2012 iMac shown as beneath. If you apply a wrong cord, the plug may not exist inserted all the fashion downward to the iMac power socket, resulting in no ability coming from the string and so your iMac won’t power on.
If you suspect your iMac power cord, apply a standard PC power cord to test. They are identical in terms of function.
If you have a sticky power push button or a faulty power button, the power button will not be able to ship a valid control bespeak to the logic board so your iMac will not turn on.
The sticky power button is caused past the dirt accumulated inside the button. iMac power button replacement is a time-consuming task even for a Mac repair professional. You lot need to remove the iMac screen, the power supply and logic lath before you can get access to the power button. Luckily, most of the time, a failed iMac power button is caused past dirt, not the electrical contact failure inside the power button. You can easily remove the dirt without replacing the button by following this procedure:
- Unplug the power cord to your iMac.
- Put the iMac on a flat desktop with the screen facing down.
Employ 1 or two drops of
lubricant to the push. Let the liquid sink to the push button.
- Wait for a few minutes until the lubricant softens the dirt.
- Keep pushing and releasing the push to become the dirt out of the button.
- Utilize a tissue to make clean the clay.
Yous may demand to repeat footstep 3 to step 5 for a few times.
Information technology is a common misunderstanding that the iMac power button is operated at the primary power voltage (110V Ac or 220-240V AC). In fact, the iMac power button is operated at 3.3V DC and this voltage is pretty safe for human being beings. Likewise, the WD-40 lubricant is electric friendly and non-conductive. Therefore the entire procedure is admittedly rubber.
3. Check for whatsoever faulty external devices
If your Mac detects the accessories attached to it have short circuits or draw an unusual amount of current from the iMac, the iMac will not turn on. This is a safety mensurate to protect your iMac. You lot tin can easily dominion out if any device is the culprit.
Unplug all the accessories attached to your iMac including printer cable, network cablevision, firewire cablevision, USB hub, external USB hard drive and Mini display cablevision. Information technology could be 1 of your peripherals causing your iMac not turning on.
4. Reset the SMC or T2 scrap
The Arrangement Management Controller (SMC) is responsible for receiving power button signals, then starts and manages the entire power-on procedure. You may consider the SMC as a tiny estimator 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 fleck into the Apple T2 Security chip starting from 2018.
Resetting the SMC on an iMac is very simple, no matter if you take a stand-lonely SMC scrap or T2 scrap.
- Remove the ability cable from the primary socket.
- Wait for 15 seconds, so plug the ability cable back in.
- Wait for 5 seconds, and so press the ability button to cheque if your iMac will plow on.
This method can be applied to Mac Mini, Mac Pro computers as they have a single power source (main power). Mac laptops require a different approach as they take dual ability sources ( charger and bombardment). 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 scrap on MacBook.
If resetting SMC can’t solve the problem of iMac not powering on, try the next method.
5. Perform a power bicycle
An iMac has iii major states:
. Performing a power cycle ways y’all strength the iMac returning to the off state.
If your iMac gets stuck in the Sleep state for some reasons, your iMac volition non respond to normal wake-upwards signals such as pressing the keyboard keys or clicking the mouse push. You need to force the iMac back to the off state by performing a power wheel.
Unplug the power cord from the main socket and await for fifteen seconds and then plug the power cable back in. Now you have forced the Mac returning to the off state. Press the ability push again to come across if your iMac tin turn on.
6. Check for signs of power
When you lot run into nothing on the screen, you lot may recall that your Mac won’t plough on. But that is not always the case. Your iMac may be
on already; merely the screen is not working. Therefore, it is vital to double-check whatever signs of power including sounds and lights to avoid a misdiagnosis.
Check sounds in a quiet environs:
Do you hear a startup chime? If yous do, your iMac is already on. Expect for 1 or 2 minutes to cheque if in that location is whatever display on the screen. If you don’t see anything on the screen, your iMac nigh likely has a screen problem.
Put your hand near the fan vent holes at the back of your iMac. Do y’all feel any air coming from the vent holes? Do you hear the fan spinning air noise, difficult deejay spinning noise, supper drive motor startup noise? Any of these signs signal that your iMac has already powered on and there are other issues preventing your MacBook from working.
Side by side, cheque lights in a dark environment:
If yous don’t come across anything on the screen, shine a flashlight to the top right-hand side corner on your iMac screen. If yous tin run across the dim text, press the screen “brightness up” button on the keyboard a few times to increment the screen effulgence. If you lot yet get dim text, yous accept a screen backlight problem. The screen backlight trouble could be caused by a faulty screen or a faulty logic board.
Press the Caps Lock fundamental, if you tin can see the light on, your iMac is running. You may as well have a screen problem.
Connect an external monitor to your iMac via a mini display port, thunderbolt port. If yous accept a display on the external monitor, you definitely accept a faulty screen
vii. Check for a faulty RAM
If you lot hear repeating beeps from the iMac, your iMac could have RAM faults that are causing your iMac to non turn on.
If y’all hear 1 beep, repeating every v seconds, it ways your iMac can’t detect any RAM. If y’all recently replaced or upgraded the retention, check to see if it was installed properly.
If you get iii successive beeps, and so a five-second pause and keep repeating, your iMac RAM doesn’t pass a data integrity check. If you recently replaced or upgraded your computer’due south RAM, check to see if information technology was installed properly. You also can attempt unlike brand names of retention modules.
8. Restore corrupted T2 security scrap firmware
Starting in 2018, Apple tree integrated the SMC fleck to a larger multifunctional chip chosen Apple T2 security flake in the new Macs. The T2 chip takes over the duty of SMC. If the T2 bit is not 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 terminate upwards with T2 flake firmware abuse. In other words, you may take bricked your iMac.
To fix a bricked iMac, you demand a working host MacBook and download the firmware from Apple tree’due south website. And so you force the bricked iMac into DFU fashion then you can transfer the firmware to the bricked iMac via a USB-C cable.
Go to Apple’due south website to download the app
Apple Configurator 2
. You lot may demand to update to the latest macOS to run the app. Open the app and make sure your host MacBook is connected to the internet.
- Unplug the ability cord of your bricked iMac.
- Use a standard USB-C cable. Connect i stop to any port of your host MacBook.
- 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.
- Press and hold the ability push button. While holding the power button, plug in the power string of your iMac. Continue to concord the ability button for about 3-5 seconds until you see the DFU logo on the Host MacBook.
- Release the power button. Now your bricked iMac is in DFU mode.
Become dorsum to your host MacBook, click to select the DFU device on the screen and select
from the menu bar. On the pull-down menu bar select
Confirm the action.
- Now the host MacBook will download the right firmware version from Apple tree’s server and install information technology to your bricked iMac. This may take upwards to 5 minutes.
- After finishing the installation, your iMac will automatically ability on. If you tin see the Apple tree logo, congratulations! You lot have successfully saved the bricked iMac.
9. Check for faulty iMac ability supply
iMac power supply failures business relationship for the majority of dead iMacs. If you have gone through all the checks discussed above and your iMac nevertheless doesn’t turn on, you most likely have a failed power supply, especially if your iMac won’t plough on subsequently power outage.
To get access to the power supply, you need to remove the iMac screen. In the pre-2011 iMacs, Apple uses eight screws to adhere the screen to the iMac frame. In the mail-2011 iMacs, Apple used double-sided sticky tapes to attach the screen to the iMac frame. Have extreme care when yous remove the iMac screen equally it is very easy to break the screen.
Unlike standard desktop PCs, the iMac ability supply is NOT sealed in a protective metal box. The unsafe high voltage department is non covered as shown on the photo below.
You can encounter the measurement point has a very high voltage of 395.1V DC. All our technicians are required to vesture protective gloves when they handle iMac hardware repairs. The gloves not only protect the technicians from accidentally touching the dangerous points only too avoid leaving finger marks on the screen. The finger marks on the older iMac screen are non easy to remove. Recollect, don’t touch anything on the power supply unit of measurement while the power unit is on.
Follow this process to bank check the iMac power supply:
- Remove the power cable from the master powerpoint.
Look for at least 10 minutes
until the large capacitors in the power supply have been completely discharged (from 395V to 0V).
- Remove the iMac screen from its aluminium frame.
- Plugin the ability cablevision back to the main powerpoint.
- Cheque for the four LED lights on the logic lath. If no LED light is on, you lot accept a faulty iMac power supply.
The four LED lights are diagnosis lights. Information technology indicates the status of the iMac logic lath. The first LED lite indicates the logic board is in standby manner. If the power supply has no output, the iMac logic board will not enter into standby manner, and then the corresponding LED light volition not plow on.
It-Tech Online is a leading Mac repair specialist in Australia. We are more than than happy to help you if yous cannot ready the issues yourself. Nosotros offer competitive prices for iMac repairs. Please contact us. Our experienced staff will call you to assess your situation and provide a gratis quote for you.
ten. Check for faulty iMac logic board
There are iv diagnostic LED lights on every model of iMacs. The location of the LEDs varies in dissimilar models. The behaviour of the LED lights can tell y’all a lot of information.
S5 Led. It indicates the logic board has received ability from the ability supply and currently in standby fashion (technical term
S5 state). In other words, the iMac is ready for you to push the button to plow information technology on.
- All_SYS_PWRGD Led. This is a technical term for “all organisation powers are skillful”. When all the system powers including the CPU, RAM but excluding GPU are ok, this light will exist on.
- GPU GOOD Led. If the GPU has received power and passed the self-checking test, this led light will turn on.
- VIDEO ON led. When the GPU has detected an iMac screen connecting to the logic lath, the GPU will turn on the backlight of the screen and the VIDEO ON led. And so the GPU will output video signals to the screen.
Remove the iMac screen equally described above and plug in the ability string to the main powerpoint. If the get-go LED calorie-free (standby light) is on, push the iMac power push and follow the instructions below to diagnose the logic lath.
- In one case you push the iMac power button, the standby light goes off. This symptom indicates that the logic board has a shorted excursion. The shorted circuit draws an unusual amount of current from the power supply, therefore the ability supply cutting off output to protect itself.
- When y’all push button the ability button, the standby light remains on, the other three lights are off. This symptom indicates that the logic board is not responding to the power button. Double-check the iMac power push button and make sure it is functional. If the power push button is ok, so the logic board is faulty.
- When you lot press the button, only ii lights are on. This symptom indicates the graphics section of the logic board is faulty. Graphics card failures are very common for iMacs manufactured betwixt 2007 to 2011.
- If three lights are on, your logic board most probable is ok. The fault is on the iMac screen.
Delight notation that the fourth LED light won’t be on until you connect the iMac screen to the logic board.
If y’all have a faulty iMac logic lath, you may cull to repair or supplant the logic lath. Apple stores and Apple Authorised Service Providers tin simply replace the logic board. Repairing the logic board requires much college knowledge and skills. A Mac repair specialist who does component-level repair can repair the logic board at a fraction of the replacement price.