Black screen on an iMac

[speckytecky]

The art teacher put her Apples away for the summer holidays and since return has plugged them back in. All but one are ok and that's an iMac which powers up but nothing happens on screen. I guess the first port of call would be the graphics card but have no idea how to open the machine. I'm a novice when it comes to opening an iMac so any advice would be extremely welcome.

[rbelson]

Try unplugging the iMac's power cable from the iMac and pressing the power button in for about 10 seconds. Then plug in the power and try pressing the power button to boot the Mac. This is an SMC (system management controller) reset and often fixes this issue.

[pooley]

Any beeps or lights etc?

[bladedanny]

You Could also try a PRAM reset. When turning the iMac on hole down CMD + OPT + P + R (it's a finger stretcher) and wait for it to reboot (you should hear the 'bong'. Solved many problems for me in the past.

 

Dan, ACTC

[speckytecky]

Thanks Dan,

 

Apart from the P & R keys I'm not sure which the keys you are on about are - our Keyboard doesn't have anything marked CMD or OPT?

 

You Could also try a PRAM reset. When turning the iMac on hole down CMD + OPT + P + R (it's a finger stretcher) and wait for it to reboot (you should hear the 'bong'. Solved many problems for me in the past.

 

Dan, ACTC

[speckytecky]

Thanks rbelson.

 

Just tried that one - sadly no joy.

 

Try unplugging the iMac's power cable from the iMac and pressing the power button in for about 10 seconds. Then plug in the power and try pressing the power button to boot the Mac. This is an SMC (system management controller) reset and often fixes this issue.

[mac_shinobi]

still got apple care or anything on it ?

 

 

or can you find and post a pic of the keyboard you have ??

 

bottom left or right normally opt is option and command or cmd ?

[speckytecky]

Thanks for that. Should be able to work it out now!!

 

It's out of warranty by some way.

 

still got apple care or anything on it ?

 

[ATTACH=CONFIG]11131[/ATTACH]

 

or can you find and post a pic of the keyboard you have ??

 

bottom left or right normally opt is option and command or cmd ?

[speckytecky]

Thanks for the advice so far sadly not it's worked. The PRAM Reset resulted in a double clunk sound - bit like the sound of someone biting into an Apple! However, still a black screen afterwards.

 

Any other suggestions please?

[HodgeHi]

If you don't hear the sound of the chime Apple's make when booting then it isn't getting that far. My iMac had a similar issue where you just got a black screen, no chime but you could hear the fan turning (listen closely )

 

IT turned out to be faulty RAM. To check there's a screw on the bottom of the case just above the foot. This will remove a cover to the RAM. There are leavers on each side. Pulling these apart should make the RAM pop out. Mine is a core 2 duo aluminium iMac. The white ones may be slightly different.

[speckytecky]

Thanks HodgeHi. Yep it's a white case and I'd found the RAM holder laptop sized 512mb on board - so getting another stick of memory and trying that would be the next move perhaps?

 

I can hear the fan going but trying all the above doesn't get it past the black screen so anything else is worth a try. It's not an old machine but is defo out of warranty. The art teacher is well switched on - knew all about PRAM and had tried that, the boot CD is in the drive but there doesn't seem to be a way of ejecting it.

[HodgeHi]

Yeah, sounds very similar to my issue. I would swap a working stick for this suspected faulty one to see if it now boots and then the working machine should fail with the dodgy stick.

[mac_shinobi]

As per PM did advise ref ifixit website and thebookyard website for replacement parts if needed ( that or fleabay ) . On the ifixit guide at least for the imac I was looking at which from the above comments seems the wrong imac - you can re apply the thermal grease ( compound ) and put it back together to see if its maybe an over heating issue, if not then maybe replace the graphics card if you can get a hold of the correct graphics card or at least a supported graphics card for the said imac

[bladedanny]

I unfortunately don't have any more suggestions as to the black screen. But in regards to the CD you should be able to hold the mouse button down whilst switching the iMac on which should eject the disc. IIRC this process is carried out before anything else. Failing that a thin pair of pliers has worked for me in the past, ruined the disk though