27" iMac Not Turning On

[Omnipotus]

Hi All,

Longtime reader of the site, but new to the forum and was hoping someone may be able to provide some advice.

I have a 2016 27" iMac - A1419
• 4.0GHz quad-core Intel Core i7, Turbo Boost up to 4.2GHz
• 8GB 1867MHz DDR3 SDRAM - two 4GB
• 1TB Fusion Drive

I went to turn it on the other day and it would not start, no activity, no chime. I did a reset and, still nothing. I unplugged the power cable and put it in a different point. It started up and I was able to login and get working, but within 1 minuted, it shut down again and would not restart.

I removed the power cable, waited 30 seconds and plugged it back in. It started again, but instantly shut down. I went through this process several times, with similar results.

Eventually, it would not start, but I could hear the fan going.

The next day, there was no fan noise, nothing happening, not matter what combination I tried.

For reference, I had also done the SMC and PRAM resets.

I ordered some screen tape, so I could remove the screen and check the LED's.

I have removed the screen and plugged the cable into a socket, tried every combination of powering on methods and not one of the LED's lights up and there is no fan noise.

Any ideas, whether I will be luck enough for this to be just a power supply, or does this indicate a logic board failure?

Thanks in advance for any and all help.

 

[Cruz3LT]

If I were in your situation, I would start with the power supply, it seems like its a good place to start since you aren't getting any power to your machine now. It's older tech, but I had a Thunderbolt Display that was showing similar issues. If I plugged it in I would get fan spin and it would stop, up until the point I no longer received fan spin. I replaced both the power supply and logic board on that unit and it works perfect. Most of the time, the used power supply on eBay you can get with a Square Trade warranty.

 

[Omnipotus]

If I were in your situation, I would start with the power supply, it seems like its a good place to start since you aren't getting any power to your machine now. It's older tech, but I had a Thunderbolt Display that was showing similar issues. If I plugged it in I would get fan spin and it would stop, up until the point I no longer received fan spin. I replaced both the power supply and logic board on that unit and it works perfect. Most of the time, the used power supply on eBay you can get with a Square Trade warranty.

Thanks Cruz3LT, I might give the power supply a go and hopefully that will work. I have priced logic boards over here and they are $2k plus, which is more than half the price of a new equivalent spec iMac.

 

[Khaleal]

It’s the power supply (most likely). I had the exact same issue with my 27” iMac (nothing happens when I press the power button, and all LEDs are off), and it was the power supply, replaced it and the iMac booted right away.
Fortunately that’s a cheap repair, as you can find genuine secondhand power supplies on eBay for around $40 (avoid the new off brand ones at all costs)

 

[Omnipotus]

It’s the power supply (most likely). I had the exact same issue with my 27” iMac (nothing happens when I press the power button, and all LEDs are off), and it was the power supply, replaced it and the iMac booted right away.
Fortunately that’s a cheap repair, as you can find genuine secondhand power supplies on eBay for around $40 (avoid the new off brand ones at all costs)

Thanks Khaleal, I'll give that a try, worse case, I can resell the power supply if it doesn't work.

 

[Crowbot]

I'm pretty sure that one of the LEDs tells you that the power supply is active. So no lights points to the power supply. Good luck with it.

 

[Omnipotus]

I'm pretty sure that one of the LEDs tells you that the power supply is active. So no lights points to the power supply. Good luck with it.

Thanks Crowbot, going to order one and see how I go.

 

[Sam Marks]

I have the same problem with my brand new 2019 iMac (2 weeks old). It started to restart itself randomly when watching 4k youtube videos until it stopped working and now it does not turn on (no fan noise or other signs). I tried every possible workaround with no luck. I called the Apple Tech Service to find a solution. I will send them the computer for a repair or a replacement.