Logic board toast?

[M_Six]

Hi All,

I have a late 2012 27" iMac that won't complete the boot up. The Apple logo shows up and the progress bar shows, but it crawls across the screen for maybe 20 minutes and then the machine appears to go into sleep mode (just goes dark). I've tried multiple USB keyboards including a wired USB Mac keyboard to attempt the various boot up options, but the keyboard does not appear to affect bootup. It's like it isn't even there. So there's no way to reset anything or get into Safe Mode or other boot options. I've tried all the USB ports. None seem to work.

I'm thinking the logic board is toast. I bought a late 2020 iMac and I have an M1 13" MBP on order, so the 2012 iMac is not really needed. But the hard drive (as far as I know) is still good and so is the screen. I really hate to dump this machine if it can be rescued, but short of replacing the logic board, I can't think of any other way to use it.

Should I just accept reality and recycle the machine? I have a co-worker who is also an Apple certified tech, so he could at least remove the glass and recover my hard drive. And I think the university bookstore here, which is an authorized Apple reseller, will take the carcass for recycling.

 

[pigoo3]

But the hard drive (as far as I know) is still good...

I wouldn't assume this. The issue could be a worn out/failing spinner hard drive or SSD (if it has an SSD). If you have an external hard drive laying around...if it doesn't already have an OS installed on it...get the macOS installed on it..then try booting the computer from it.

If booting from an external hard drive isn't successful...then your iMac may have more serious issues. If it does boot fine from the external drive...then the internal drive is failing or failed.

- Nick

 

[M_Six]

The problem is that I have no way to choose the boot drive.

 

[pigoo3]

...I have no way to choose the boot drive.

Sure you do.

Don't need to wait for the computer to fully boot up to choose the boot drive. As soon as you hear the startup chime...press & hold the Option key...then select the boot drive.

Should have the iMac's internal drive and an attached external drive to choose from (assuming a compatible macOS is installed on the external drive). You would choose the external drive. Once this is done...you can release the Option key.

- Nick

 

[M_Six]

I must not be stating the case correctly. I could stand on the Option key and it would make no difference. It *does not* recognize any key combinations even if I hold them and hit the power button. Even if I hold the Option key, it still goes to the Apple logo and then starts the slow progress bar.

 

[chscag]

Probably not the logic board per se, however, sounds like it could be a bad GPU which is known to happen in that model.

It won't matter though since the logic board itself would probably have to be swapped out to replace the GPU.

 

[M_Six]

Probably not the logic board per se, however, sounds like it could be a bad GPU which is known to happen in that model.

It won't matter though since the logic board itself would probably have to be swapped out to replace the GPU.

That's what I'm thinking. The whole board is obviously not shot as it attempts to boot, but if any part of the board is bad, the whole thing needs to be replaced. And since that model can't update past Catalina, it's probably not worth throwing any money into it. It's just a shame to have to trash a machine with such a nice display.

 

[chscag]

You don't have to trash it. Sell it for parts on eBay, especially since the display is good and it's a retina. I'm sure you can get buyers that are willing to go for it.

 

[pigoo3]

Even if I hold the Option key, it still goes to the Apple logo and then starts the slow progress bar.

That's because (from what's been stated so far)...you only have one drive to choose from (the internal drive). You need a 2nd drive attached (with a compatible macOS installed on it)...so when the option key is pressed...there's a 2nd boot option to choose from.

If your logic board has failed in some way...and part of that is making the USB ports inoperable (thus the keyboard not working)...ok. But I would rather not "give up the ship" quite yet until trying to boot from a 2nd drive has been tested.

Also...in post #1 it was stated "attempt the various boot up options". What boot options have you tried?

If you do not want to try booting up from a 2nd drive...that's your choice. But I would feel better if it has been tried before sending this computer to the scrap/recycle heap!

- Nick

 

[M_Six]

I have tried every key option I know. Safe mode (Shift key), the Option key, the CMD-R keys (recovery), Option-CMD-P-R, etc. None of them have any effect. I also don't get the startup gong sound. Today I started it and just watched. There are no indications of power to the keyboard for the first few minutes, then the caps lock light comes on for a few seconds and then turns off, then on again. Rinse and repeat. The progress bar gets 8/10 of the way across, sits there for 15 minutes or so, then it reboots and starts the process over again.

I can try the "boot from external" method, but as I've said, the keyboard does not seem to have any effect. And I've tried this keyboard with other machines and it works fine.

 

[pigoo3]

It does sound like if you've tried multiple USB keyboards...and you get no indication that keystrokes from any keyboard are being accepted by your iMac...that at least the USB ports are not working (and maybe more).

If it were me...I personally would still want to try the troubleshooting step of attaching an external HD to the iMac (with a compatible macOS installed on it)...just to see what happens. Yes I know this external HD would most likely be plugged into one of the iMac's USB ports (which seem to be faulty). I would just want to do this relatively simple thing before trashing/recycling the iMac.

- Nick

 

[M_Six]

I'll give that a shot. I'll be shocked if it recognizes a drive attached to the USB ports, but it can't hurt to try.

 

[M_Six]

Can't seem to find a download for Catalina or any other MacOS except Big Sur. I don't see them in the Apple Store and all the directions I find online end up with an error page or the Apple Store with other apps, but no OSs. Did Apple stop offering downloads of previous OSs?

 

[pigoo3]

I had to do some macOS reinstalling recently on an old Mac Pro I have...and I also ran into some issues finding a good location to download older macOS versions. Here's the best link I found for downloading older macOS versions (Apple site link):

How to download and install macOS - Apple Support

Download and install current or previous versions of the Mac operating system on compatible Mac computers.

support.apple.com

- Nick

 

[M_Six]

I've seen that page. This is what I get if i click on the Catalina link. If I choose Music, it fails. If I switch to App Store, it opens the App Store and then says it Cannot Connect to the App Store.

 

[M_Six]

Does that on my laptop and office iMac as well.

 

[pigoo3]

When I was doing the macOS reinstalling on my older Mac Pro...I was using the El Capitan link.

If you're trying to download a older macOS to do some troubleshooting with your 2012 iMac...maybe try something older than Catalina. If one of the others work for you...install it...then upgrade it via "Software Update" under the Apple menu.

I should also mention the downloads on this page may only be "upgrade" downloads...not stand alone installers for drives with no macOS on them. In my case I had a really old macOS version installed on the drive I was working with (10.6)...and used the El Capitan link to upgrade it.

- Nick

 

[M_Six]

That must be it because I can't download anything. We have older OS dmg images at the office, but I when I try to create an installable USB, I always hit a brick wall. I don't know why this has to be such a hassle. Creating an install USB should be a simple procedure. I do have an Apple Super Drive and I can find an older OS DVD at the office, so maybe I'll give that a shot.

 

[chscag]

The problem you may be running into is that with the older versions of macOS, even though you may have USB installers, it that the certificate likely has expired.

There is a procedure for getting around that. See if you can find a post by Randy Singer explaining on how to work around an expired certificate.

 

[pigoo3]

I've seen some "tricks" for getting around an expired certificate...which involve changing the date on the computer to a date before the expiration of the certificate. When I tried it...it didn't work. Maybe there are other possibilities.

- Nick