2013 27" iMac - Weirdest Fault Ever! - Need some help please!

[iFix Centre]

Hello,

We have a very odd case come into our workshop.

a 27" 2013 iMac that will power up but display nothing. No chime, no display, no backlight.

We initially thought...GPU!!

Bear in mind, we already tried going into safe mode/recovery/apple diagnostics/external drive...none of which worked because we got no chime, display anything!

So we opened it up, and it was completely full of dust. Customer hadn't cleaned it since he bought it and had heavy building work inside his home.

Seeing the dust reinforced our theory of GPU.

We checked the LED lights on the logic board and only LED 1 and LED 2 turned on when powering up the iMac.

At this point we were 100% it was the GPU and advised the customer it needed a new logic board.

Customer agreed and we sourced a new logic board.

New logic board arrived and fitted it. Customer had a fusion drive set up, so we transferred it over.

Plugged into the power, press the power button....exactly the same fault. Powers up, no chime, no display, no backlight.

After numerous unplugging and plugging and thinking...we disconnected the SATA disk cable and low and behold...the iMac turned on, chimed and displayed the folder icon.

We immediately took out the hard drive, and scanned it externally to find it is badly damaged and pretty much failed. We cloned it successfully onto a working drive, and when we put that into the iMac we were back to the same fault of no chime, no display.

We put in another drive that has OS X preinstalled and the iMac booted up into fine.

So I assume the hard drives partition is somehow stopping the iMac to physically turn on and chime normally.

Has anyone heard of this?

And is there anyway we can recover the data from the hard drive?

Thanks in advance.

 

[mikehalloran]

Has anyone heard of this?

Yes

And is there anyway we can recover the data from the hard drive?

Maybe. Put it into an external dock (TB is ideal). Run Repair from Disk Utility. If you see the same errors in red 3x in a row, give up.

If, however, you see that the errors change, run it again—and again—as many times as it takes. DU often fixes only one error at a time. I've had to run it on some HDDs over 50 times before it shows green. If it shows green, get the data off that drive ASAP because that state won't last long. It's quite possible that, once you turn it off, it will become a brick.