2009 27" imac - white screen

[halap3n0]

Hi all
Now this is a bit of old machine I know, but still has a nice screen, dedicated GPU, and performance is fine.
It won't boot normally, I get the grey progress bar under the apple logo, not startup chime for some reason, and then just goes to a white screen.
Cmd-R for recovery mode does not work.
Cmd-S does work and I can get to terminal, so I can copy my data off. So I don't mind formatting. I tried fsck -fy and it did nothing.
I also tried resetting the NVRAM which did nothing.
Any ideas what might be wrong? If it is the HDD, I am not averse to opening it up and putting in an SSD for £100 - cheaper than buying a new 27" imac (my wife likes the big screen). Even if the machine lasts another year, if it completely dies I can always reclaim the SSD.

So, does anyone have an idea what might cause the white screen issue, is it likely hard disk? If not I guess I am wasting my time.

Thanks

 

[CoastalOR]

It won't boot normally, I get the grey progress bar under the apple logo, not startup chime for some reason, and then just goes to a white screen.
Cmd-R for recovery mode does not work.
Cmd-S does work and I can get to terminal, so I can copy my data off. So I don't mind formatting. I tried fsck -fy and it did nothing.
I also tried resetting the NVRAM which did nothing.
Any ideas what might be wrong? If it is the HDD, I am not averse to opening it up and putting in an SSD for £100 - cheaper than buying a new 27" imac (my wife likes the big screen). Even if the machine lasts another year, if it completely dies I can always reclaim the SSD.

So, does anyone have an idea what might cause the white screen issue, is it likely hard disk? If not I guess I am wasting my time.

Which OS are you running? If you are still using Snow Leopard, that shipped with your iMac, then there would not be a Recovery partition (command+r) since 10.6 did not support it.

Try booting in Safe mode (hold the shift key at startup). What happens?

Can you try starting up from the gray Install disk that shipped with you iMac? If yes, then run Disk Utility to see what it shows for your iMac.

 

[halap3n0]

Which OS are you running? If you are still using Snow Leopard, that shipped with your iMac, then there would not be a Recovery partition (command+r) since 10.6 did not support it.

Try booting in Safe mode (hold the shift key at startup). What happens?

Can you try starting up from the gray Install disk that shipped with you iMac? If yes, then run Disk Utility to see what it shows for your iMac.

I got it as a hand me down a few months ago. I downloaded the latest version at the time via the store onto USB and blew the disk away.

Safe mode didn't work either.

I can recreate another USB and try that?

 

[CoastalOR]

I got it as a hand me down a few months ago. I downloaded the latest version at the time via the store onto USB and blew the disk away.

Safe mode didn't work either.

I can recreate another USB and try that?

It sounds like you must have downloaded Sierra. If you have another Mac, you try downloading Sierra again, make a bootable USB installer, boot your iMac with the USB installer, run Disk Utility and see what it shows as status of your internal drive and OS. If everything checks out, then you can use the bootable USB to install a fresh copy of Sierra.

 

[nambuccaheadsau]

If you have to go the way of replacing the dive, be aware should this iMac be a 2009 and onwards model it has a heat sensor cable, and Apple designed these to be used with precisely the same drive as the original. No heat sensor or a different drive, the iMac fans roar like a 747 moving down the runway.

Fortunately OWC make a heat sensor kit to get around this problem

https://eshop.macsales.com/item/OWC/DIDIMACHDD09/