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Logic board or left I/O board problem?

My MacBook Pro has been through %$#&. A long time ago I dropped it, cracking the screen. Since then I have replaced the entire display housing (isight, screen, back cover etc.), and the hard drive. Nearly a year after repairing it the inverter board went bad. The backlight for the screen would not turn on but I could still see the screen if held at the right angle under the right light.

When replacing the inverter board everything else broke. I'm not sure if I accidentally destroyed it with an electro-static discharge or if it was just poor timing. At this point I gave up and bought a new MacBook Pro. Putting the failed one aside for another time.

It has been over a year and I decided to have another try at fixing it since logic boards are now on eBay for around $250. Because it would not charge the battery I started by buying a new left I/O board, when that didn't fix the problem I ordered a new logic board.

I installed both the new left I/O board and the new logic board but I am still having trouble. when I press the power button:

  • If the laptop is running on battery then, I hear the Hard drive begin to spin up, make a horrible clicking sound and repeat. The fans make a small jerking motion but do not spin up, the screen stays black and I DO NOT hear the start-up beep.
  • If the power cord is plugged in, the hard drive spins up and stays spinning WITHOUT making the clicking sound that is heard on battery. But nothing else improves, the screen does not turn on, the fans make a jerking motion but do not start spinning, and there is no start up beep.
  • If the power cord is removed the hard drive continues to spin normally.
  • The new I/O Board does charge the battery.

Connecting a DVI cord has no effect (ruling out a bad screen?).

My question is: How do I know if my problem is related to a bad logic board or a bad left I/O board? Is there any way I can test each piece to prove which one is defective?


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Soluzione Prescelta

If you connected to an external monitor and got no picture then that would be a logic board or GPU issue, plus you say that the new I/O board charges the battery, so all signals point to a bad board.

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+ agreed


This is what I thought but I wanted to check with others. Thank you very much.


No prob Derek, good luck with your machine.


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To eliminate the hard drive from the problem, I'd remove it and use an external enclosure or adapter and check it out with Disk Utilities.

Here's the adapter:

Here's an enclosure: [prodotto collegato mancante o disabilitato: IF107-055]

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I will try your suggestion, however I do not suspect a hard drive issue. The hard drive had been replaced a while ago and even if the hdd was bad it should still get to the apple logo, correct?



with the clicking sound, I'd check it anyway


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Hello Derek,

It's been a while but if you are still trying to resolve this issue, I have exactly the same symptoms on my A1150 2.0 GHz Core Duo 15" MacBook Pro.

I have now identified a pattern by which I can reproduce the problem (does not boot - not even the chime or the LED in front) and also START the MacBook Pro.

Once started, the MacBook Pro works perfectly. It can even go to sleep over a long period of time, restart, do a full Mac OS install, etc.

So here it is: the MacBook will only start WHEN WARM! You can warm it up two ways:

1. plug the power adapter, push the Start button (you while hear the hard disk spin up)... wait 3 to 5 minutes. Force shut down by pressing and holding the Start button for 5 seconds. Once off, immediately push the Start button again and it will boot.

2. Shut it down if the disk is spinning and put the MacBook Pro for a couple of minutes on a warm surface (I put it on top of the central heating radiator here - temp around 50 °C) . It will then start normally.

Once started, I can use it for days without any problem. I can even shut it down and start it if I don't wait too long (less than a minute).

I took it to the Apple Store and the guys at the Genius bar used all their diagnostic tools and couldn't find a problem. TechTool Pro doesn't see any problem either. I check the PRAM battery and it reads 3.2 volts. I took apart the mother board and left I/O board and replugged all connectors. No change.

I have also swapped the RAM and hard disk with another MacBook Pro. reset the ELC, PRam, etc? No problem there...

Having found this reliable way to start the MacBook Pro and given that I seldom shut it down (sleep is fine) I can use it but, I sure would like to eliminate this issue for good.

I hope that someone on the board can help.

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It's been quite a while, but I had the same problem with my A1150 & I was working on it one day, but forgot to disconnect the battery & when I unplugged both fans, it magically started. I tried to figure out every different thing that could possibly be happening & even switched out the i/o board, but the only way it will start is if I unplug both fans & then plug back in as soon as the optical drive starts up. I couldn't explain it if I had to but I'm on it right now & it works as if nothing is wrong once it starts, I just can't get it to start without unplugging the fans first?? Completely Random


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Hi Jeguar

I have had the same issue the last 2-3 month - if my Macbook Pro 1.83 A1150 lost the power or ran out of power I have really difficult to get it started - I have reset everything and sometimes I am lucky to get it started - but I haven't found the way - so now I was looking for a new DC-board or I/O-board for replacement.....and I just stumpled over your altenative

And it worked for me the first time - I started the computer for 5 min and turned it off and on again and it started for the time after a weeks struggle

But still - I would like to eliminate this so if any got a solution please let me know



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I have same problem. My macbook pro starts only after heating it by forcing it to start with dc power for several hours, but under normal condition when i press the power button the fans start, HD powers up, so does Super drive but only for a few seconds.

I had the logic board replaced a few months ago because the screen didn't turn on, now this problem is really turning me mad. :-(

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Derek Brown sarà eternamente grato.
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