Imac G4 Won T Turn On

Fix the iMac not turning on problem step-by-step

There are many potential reasons why your iMac won't turn on. The method y'all use to gear up them volition 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 problems related to the logic board.

The major difference between an iMac and a MacBook is the bombardment. An iMac doesn't rely on battery power, therefore troubleshooting the "iMac won't plough on" trouble is easier than troubleshooting the "MacBook won't turn on" trouble. If you lot have a MacBook problem, see our commodity MacBook Won't Plough On? 10 Means To Set up 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 instance, hither are steps to accept when things do go wrong:

i. Make sure your iMac is receiving power

This is a simple step, but information technology is a top priority. Cheque if the power cable is undamaged and deeply plugged into your iMac and a working electric outlet. If you're non sure about the outlet, test information technology with a lamp or a mobile phone charger.

The power cord plug (the terminate connecting to the iMac) of the post-2012 iMac is dissimilar from the old cord of the pre-2012 iMac shown as below. If you utilise a wrong string, the plug may not be inserted all the way down to the iMac power socket, resulting in no power coming from the cord so your iMac won't power on.

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

2. Check for stuck power push button

If yous have a pasty ability button or a faulty power button, the power button volition not be able to ship a valid control point to the logic board then your iMac will not turn on.

The gluey power button is caused by the dirt accumulated inside the button. iMac ability push button replacement is a fourth dimension-consuming task even for a Mac repair professional. You demand to remove the iMac screen, the power supply and logic board before you lot can get access to the power button. Luckily, most of the time,  a failed iMac ability button is caused by dirt, non the electrical contact failure within the power button. Yous can easily remove the dirt without replacing the button by following this procedure:

1. Unplug the power cord to your iMac.
2. Put the iMac on a flat desktop with the screen facing down.
3. Apply ane or two drops of WD-40 lubricant to the button. Allow the liquid sink to the button.
4. Wait for a few minutes until the lubricant softens the clay.
5. Keep pushing and releasing the button to get the dirt out of the button.
6. Use a tissue to clean the clay.
7. You lot may need to repeat stride 3 to step v for a few times.

It is a mutual misunderstanding that the iMac power push button is operated at the main 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 beings. Also, the WD-40 lubricant is electrical friendly and non-conductive. Therefore the entire procedure is absolutely safe.

iii. Check for any 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 plough on. This is a safety measure to protect your iMac. You can hands rule out if any device is the culprit.

Unplug all the accessories attached to your iMac including printer cable, network cable, firewire cable, USB hub, external USB hard drive and Mini display cable. It could be i of your peripherals causing your iMac non turning on.

4. Reset the SMC or T2 chip

The System Management Controller (SMC) is responsible for receiving power button signals, so starts and manages the unabridged power-on process. You may consider the SMC as a tiny computer 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 flake into the Apple tree T2 Security chip starting from 2018.

Resetting the SMC on an iMac is very simple, no matter if yous have a stand up-alone SMC flake or T2 flake.

1. Remove the power cable from the main socket.
2. Wait for 15 seconds, and so plug the power cable back in.
3. Wait for v seconds, 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 have a single power source (main power). Mac laptops crave a different approach as they accept dual power sources ( charger and battery). You tin can't easily disconnect the internal battery. If you want to reset the SMC on a MacBook, see our commodity Reset SMC or T2 chip on MacBook.

If resetting SMC can't solve the problem of iMac non powering on, try the adjacent method.

5. Perform a power wheel

An iMac has three major states: Off , Sleep and On . Performing a power cycle means y'all force the iMac returning to the off country.

If your iMac gets stuck in the Slumber country for some reasons, your iMac will not reply to normal wake-up signals such as pressing the keyboard keys or clicking the mouse button. Y'all need to force the iMac dorsum to the off country past performing a power bicycle.

Unplug the power cord from the chief socket and wait for fifteen seconds then plug the power cable back in. Now you have forced the Mac returning to the off state. Press the power push over again to encounter if your iMac tin turn on.

six. Cheque for signs of power

When you run across nothing on the screen, you may remember that your Mac won't plough on. Only that is not always the case. Your iMac may exist on already; but the screen is not working. Therefore, information technology is vital to double-bank check whatever signs of power including sounds and lights to avoid a misdiagnosis.

Cheque sounds in a quiet surroundings: Do yous hear a startup chinkle? If you practise, your iMac is already on. Wait for ane or 2 minutes to cheque if there is whatever display on the screen. If you don't see annihilation on the screen, your iMac most likely has a screen problem.

Put your paw near the fan vent holes at the back of your iMac. Do you feel any air coming from the vent holes? Do you hear the fan spinning air noise, hard disk drive spinning noise, supper bulldoze motor startup noise? Any of these signs indicate that your iMac has already powered on and there are other bug preventing your MacBook from working.

Next, check lights in a dark environment: If you don't see anything on the screen, smooth a flashlight to the pinnacle right-hand side corner on your iMac screen. If you can see the dim text, press the screen "effulgence up" button on the keyboard a few times to increase the screen effulgence. If you however get dim text, you have a screen backlight problem. The screen backlight problem could exist caused past a faulty screen or a faulty logic board.

Press the Caps Lock key, if you tin 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 display on the external monitor, you definitely have a faulty screen

7. 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 non turn on.

If you hear 1 beep, repeating every five seconds, it ways your iMac can't notice any RAM. If you recently replaced or upgraded the retentiveness, check to see if it was installed properly.

If you go three successive beeps, then a 5-second pause and continue repeating, your iMac RAM doesn't pass a information integrity check. If yous recently replaced or upgraded your computer'south RAM, bank check to run into if it was installed properly. You lot besides tin can attempt unlike brand names of retentiveness modules.

8. Restore corrupted T2 security fleck firmware

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

If you lot updated your iMac'southward macOS to i that contains a device firmware update (DFU) just failed to consummate the whole procedure 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. Then you lot force the bricked iMac into DFU fashion so yous 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 lot 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 net.
2. Unplug the ability cord of your bricked iMac.
3. Utilize a standard USB-C cable. Connect one cease to any port of your host MacBook.
4. Connect the other stop of the USB-C cablevision to the master port of your bricked iMac. The primary port is the USB-C port adjacent to the Ethernet Port.
5. Printing and hold the ability push button. While holding the ability push, plug in the ability cord of your iMac. Continue to hold the power button for nigh three-5 seconds until y'all run across the DFU logo on the Host MacBook.
6. Release the power button. Now your bricked iMac is in DFU fashion.
7. Go dorsum to your host MacBook, click to select the DFU device on the screen and select Action from the carte du jour bar. On the pull-down menu bar select Accelerate and select Revive Device. Confirm the activity.
8. Now the host MacBook will download the correct firmware version from Apple'southward server and install it to your bricked iMac. This may take up to v minutes.
9. After finishing the installation, your iMac will automatically ability on. If you can come across the Apple tree logo, congratulations! You have successfully saved the bricked iMac.

ix. Bank check for faulty iMac ability supply

iMac power supply failures account for the majority of expressionless iMacs. If you take gone through all the checks discussed above and your iMac still doesn't plow on, yous virtually probable take a failed ability supply, peculiarly if your iMac won't turn on after ability outage.

To go access to the power supply, you need to remove the iMac screen. In the pre-2011 iMacs, Apple uses 8 screws to attach the screen to the iMac frame. In the post-2011 iMacs, Apple used double-sided viscous tapes to attach the screen to the iMac frame. Take farthermost care when y'all remove the iMac screen as information technology is very easy to break the screen.

Different standard desktop PCs, the iMac ability supply is NOT sealed in a protective metallic box. The dangerous high voltage section is not covered equally shown on the photo below.

Y'all can run across the measurement indicate has a very high voltage of 395.1V DC. All our technicians are required to clothing protective gloves when they handle iMac hardware repairs. The gloves not only protect the technicians from accidentally touching the dangerous points but too avoid leaving finger marks on the screen. The finger marks on the older iMac screen are non piece of cake to remove.  Recollect, don't touch anything on the power supply unit while the power unit is on.

Follow this process 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. Bank check for the four LED lights on the logic board. If no LED lite is on, yous have a faulty iMac power supply.

The four LED lights are diagnosis lights. It indicates the status of the iMac logic board. The beginning LED low-cal indicates the logic board is in standby mode. If the power supply has no output, the iMac logic board will not enter into standby mode, and then the respective LED low-cal will not turn on.

IT-Tech Online is a leading Mac repair specialist in Australia. We are more happy to help y'all if you cannot set up the problems yourself. We offer competitive prices for iMac repairs.  Please contact the states. Our experienced staff will phone call yous to assess your state of affairs and provide a free quote for you.

10. Bank check for faulty iMac logic board

At that place are four diagnostic LED lights on every model of iMacs. The location of the LEDs varies in unlike models. The behaviour of the LED lights tin can tell you a lot of information.

1. S5 Led. It indicates the logic board has received power from the power supply and currently in standby style (technical term S5 state). In other words, the iMac is ready for you to push button the button to plow 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 but excluding GPU are ok, this light will be on.
3. GPU Proficient Led. If the GPU has received ability and passed the self-checking test, this led light volition turn on.
4. VIDEO ON led. When the GPU has detected an iMac screen connecting to the logic board, the GPU volition turn on the backlight of the screen and the VIDEO ON led.  Then the GPU will output video signals to the screen.

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

1. One time you push the iMac power push, the standby calorie-free goes off. This symptom indicates that the logic board has a shorted circuit. The shorted circuit draws an unusual amount of electric current from the ability supply, therefore the power supply cut off output to protect itself.
2. When you push the power push button, the standby lite 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 button and make sure information technology is functional. If the ability button is ok, then the logic board is faulty.
3. When you press the button, only two lights are on. This symptom indicates the graphics section of the logic board is faulty. Graphics card failures are very mutual for iMacs manufactured between 2007 to 2011.
4. If 3 lights are on, your logic board virtually probable is ok. The fault is on the iMac screen.

Delight notation that the 4th LED light won't be on until you lot connect the iMac screen to the logic board.

If you have a faulty iMac logic lath, you may choose to repair or replace the logic lath. Apple stores and Apple Authorised Service Providers can just supervene upon 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.

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

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