Using Target Disk Mode to troubleshoot an iMac

[Scottsdale]

I have a Late 2006 24" iMac that seems to startup fine, BUT the screen is dark. Connecting to an external display also has a dark screen. I can toggle on voice over and hear that everything seems to be fine. This seems like a GPU problem, but I would like some sort of verification before buying a new GPU for it. It is a family member's iMac, and he really cannot afford to waste money, so I cannot be wrong and buy a $300 GPU for it (about $190 used on eBay with 90 day warranty).

The thing is I read that Target Disk Mode can be used for troubleshooting. I can TDM into it, but I wonder if there is any way to read error logs or something to actually find any sort of errors reporting that might definitely indicate the GPU or something else???

Any help will be greatly appreciated.

 

[jayhawk11]

I have a Late 2006 24" iMac that seems to startup fine, BUT the screen is dark. Connecting to an external display also has a dark screen. I can toggle on voice over and hear that everything seems to be fine. This seems like a GPU problem, but I would like some sort of verification before buying a new GPU for it. It is a family member's iMac, and he really cannot afford to waste money, so I cannot be wrong and buy a $300 GPU for it (about $190 used on eBay with 90 day warranty).

The thing is I read that Target Disk Mode can be used for troubleshooting. I can TDM into it, but I wonder if there is any way to read error logs or something to actually find any sort of errors reporting that might definitely indicate the GPU or something else???

Any help will be greatly appreciated.

TDM isn't going to let you run Diagnostics on the unit, though. It's just a really fancy external hard drive when it's a Target Disk.

I would take it in to an Apple Store. They can run a GPT on it and see if it fails there.

Side note...replacing the GPU in an iMac? You're brave

 

[Scottsdale]

TDM isn't going to let you run Diagnostics on the unit, though. It's just a really fancy external hard drive when it's a Target Disk.

I would take it in to an Apple Store. They can run a GPT on it and see if it fails there.

Side note...replacing the GPU in an iMac? You're brave

That is a good idea. I can take it in and at least get a verification of GPU failure.

I definitely don't want to deal with this, and if it was mine I would dump it. However, anything for family.

Anyone else have any ideas? I keep reading about troubleshooting via TDM.