iMac - Grey screen boot

[Harry1980]

Hi,

 

I have a iMac which is about 4-5 years old. It has suddenly started to boot with a grey screen and nothing happens. I have checked online and it says to disconnect any devices other then the keyboard and mouse and see what happens. I have tried that and still the same issue. I have even disconnected the keyboard and mouse and still the same. Now when I start it, it makes a crackling noise which is coming from the back of the monitor.

 

Any ideal what the problem is or how I can rectify it?

 

Thank you in advance.

[njc235]

Sounds like a major fault. The crackling sound you describe could be the hard disk 'hunting'. If indeed it is a crackling then it could be even more serious. I would take it to an authorised repair centre.

[mac_shinobi]

see my post on your other post regards to not being able to eject your optical drive - if you are ok to buy the tools you require and get the relevant parts you could repair it yourself and get it working again seeing as this apple mac is over 4 years old so am guessing there is no apple care etc

[Harry1980]

Sorry guys, both my threads are related to 2 different iMac's. Both iMacs have faults with them 1 is ejecting the CD and the other boots up with a grey screen and makes a crackling noise.

[Arthur]

the other boots up with a grey screen and makes a crackling noise.

Does it sound like an electrical crackling noise or is it more of a clicking / clunking / whirring noise?

 

Have you tried booting the Mac into single user or verbose mode and/or safe mode?

Edited May 7, 2014 by Arthur

[mac_shinobi]

Does it sound like an electrical crackling noise or is it more of a clicking / clunking / whirring noise?

 

Have you tried booting the Mac into single user or verbose mode and/or safe mode?

 

Presume you are trying to establish if its the hard drive. ( if its a clicking / clunking / whirring noise ) or the power supply if its more a crackling noise or similar

 

So either the hard drive is knackered with bad sectors and issues with the read / write heads or the power supply is faulty and not providing enough power

 

Am guessing those are along the lines you are thinking of @Arthur

[Mikee_Amsys]

Nice quick and easy test: If you have a like(ish) for like machine, start the working machine in Target Disk Mode with a firewire cable.

 

With the mac that is failing to boot, hold down ALT as you boot and it should skip trying to launch the OS and offer you a peek at every drive connected, such as the Superdrive, USB caddies etc. Select the HDD of the working machine in Target Disk Mode as your boot source.

 

If it boots the OS, then you know all of the problems are related to the HDD in the faulty machine.