Imac wont boot after replacing logic board, help!

Grubster

macrumors member
Original poster
Jun 25, 2010
57
2
Hi, my imac died and was told I needed a logic board. Mid 2007 imac 24. Replaced logic board (technician at independ repair shop), it no longer beeps like crazy but only booted up once or twice. Most of the time it just hangs. I have reset pram, reset SMC, tried safe mode and verbose mode, plus safe+ verbose. All hardware tests pass as well. Tech had it booted to an old version of tiger, and a version of osx off different drives. Next day, same thing, won't boot again. I got home, it booted, but kept freezing, mouse moves, nothing else works. Reboot, and dead again.

Can someone help me read the errors in verbose model I don't know what they mean. I can't attach a picture, but messages say things like:

Smcreadkeyaction error: smcreaddata8 failed for keyBEMB (kSMCKeynotfound)
Smcreadkeyaction error: $num ksmckeynotfound (0x84) fkeyhashtable=0x0

Previous shutdown cause: 3
Smcinithelper error: MMIO revamp. == NULL - fall back to old smc Mode.

Considerrrbuildofprelinkedkernal pure build has expired.
 

Grubster

macrumors member
Original poster
Jun 25, 2010
57
2
What keyboard are you using? Wireless or wired?
Wired

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I believe the tech mentioned he checked for firmware updates. How do I check if computer wont boot? I don't recall ever updating firmware on my old logic board.

One more thing to add, board was used, not new. Seller told me it worked fine, selling as his a
LCD cracked.

I do have a new logic board coming that I won on ebay. Retailers are just asking too much money to make it worthwhile to buy one.
 

Robert Davies

macrumors 6502
Jul 28, 2011
316
3
People's Republic of Wrexham
Wired

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I believe the tech mentioned he checked for firmware updates. How do I check if computer wont boot? I don't recall ever updating firmware on my old logic board.

One more thing to add, board was used, not new. Seller told me it worked fine, selling as his a
LCD cracked.

I do have a new logic board coming that I won on ebay. Retailers are just asking too much money to make it worthwhile to buy one.

You indicated that the tech had it booted with an old OSX? That may be one place to start.

Another place may be to see if the machine will boot off the disks that came with it (CDs or DVDs)

Firmware updates are/were supplied via 'software update' so it was often just a case of click to agree, rather than having to make a special effort to keep the firmware updated. Whereas with a lot of corporate machines that I have seen updates were rarely done, and its usual that parts on the secondhand market are harvested from ex-corporate machines…

Which is what got me thinking about why it would boot on an old OS but not a more modern one…

Though to be honest it is probable that one ore more of the following may be true:

1. The original problem was other than with the logic board.
2. The replacement logic board is also broken.
3. The replacement was fitted incorrectly/other faults developed during fitment.

Oh… and those 'errors' are not errors as such, merely the OS interrogating the machine to see what it has got attached to it - my Mac Pro and MacBook Air have similar responses during verbose boot.

Sorry to be not much more assistance.

-Rob
 

Grubster

macrumors member
Original poster
Jun 25, 2010
57
2
You indicated that the tech had it booted with an old OSX? That may be one place to start.

Another place may be to see if the machine will boot off the disks that came with it (CDs or DVDs)

Firmware updates are/were supplied via 'software update' so it was often just a case of click to agree, rather than having to make a special effort to keep the firmware updated. Whereas with a lot of corporate machines that I have seen updates were rarely done, and its usual that parts on the secondhand market are harvested from ex-corporate machines…

Which is what got me thinking about why it would boot on an old OS but not a more modern one…

Though to be honest it is probable that one ore more of the following may be true:

1. The original problem was other than with the logic board.
2. The replacement logic board is also broken.
3. The replacement was fitted incorrectly/other faults developed during fitment.

Oh… and those 'errors' are not errors as such, merely the OS interrogating the machine to see what it has got attached to it - my Mac Pro and MacBook Air have similar responses during verbose boot.

Sorry to be not much more assistance.

-Rob
The old logic board was beeping SOS.
with new board, it took a really long time to boot, but did boot to mavericks. After he got it to boot to different osx version, it never booted to it again. It wouldn't boot to any OS. It was working for me but eventually froze when I was resetting up my trackpad. But I was freezing before and did unfreeze for. A bit.

it passed all hardware tests.

How do I check firmware update without loading to OSX. can I check and update from single user mode/ terminal?

Also, I just remembered, after It finally booted, software update dpped up. It mentioned nothing about firmware updates, only iPhoto and iTunes updates. I believe firmware updates come through that way.

I am hoping to get new logic board today. I'm doubting it was fitted wrong. This guy is supposed to be certified apple repair shop and did know what he was doing. He could only spend so much time to make it worth his while as he wouldn't charge me if he couldn't fix it. I'm going to put the next board in myself.
 
Last edited:

Robert Davies

macrumors 6502
Jul 28, 2011
316
3
People's Republic of Wrexham
I recommend that most people have a go at repairing their Macs, you learn so much, and develop a much greater understanding of the machine.

Or maybe that's just me? :)

Anyway… I suspect that if the firmware was incorrect it would not have booted at all.

Moving on to replacing the logic board, there's loads of tips and guidance here:

http://www.ifixit.com/Device/iMac_Intel_24%22_EMC_2134_and_2211

I recommend that as you remove any screws or sub assemblies, make a basic outline drawing of the iMac, and poke the screws through the paper in the same place they would be on the iMac.

Oh, and read up on anti-static procedures.
 

Grubster

macrumors member
Original poster
Jun 25, 2010
57
2
Thanks for the tips. After installing the logic board, is there anything I need to do? I have no clue what firmware it would have. It was bought off eBay and described as new. But who knows what firmware it shipped with.
 

Robert Davies

macrumors 6502
Jul 28, 2011
316
3
People's Republic of Wrexham
Thanks for the tips. After installing the logic board, is there anything I need to do? I have no clue what firmware it would have. It was bought off eBay and described as new. But who knows what firmware it shipped with.
Until you've booted it into Mac OSX and clicked on > Apple Menu > About this Mac > More info, you won't know what firmware it's running. Though it may be worth checking with the link I gave earlier on to see what firmware it should be running.
 

Grubster

macrumors member
Original poster
Jun 25, 2010
57
2
Until you've booted it into Mac OSX and clicked on > Apple Menu > About this Mac > More info, you won't know what firmware it's running. Though it may be worth checking with the link I gave earlier on to see what firmware it should be running.
Ok, so I have replaced logi board, now screen doesn't come on. I have no clue what is wrong. I checked LCD cables 3 times. I tested before putting bezel back on. There are 4 diagnostic lights, only 3 of them light up. Fourth is for LCD of course. I don't know where this leaves me.

LCD is not bad as it just worked on prior logic board.