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View Full Version : Possible Motherboard but would like some advice


xxsilk109xx
10-05-2011, 03:43 PM
I have a macbook 13" in here that wont power on. Customer brings it to me and it wont power on. So I pull the ram out and try new ram, pulled HD etc.
It is charging the battery and with the battery pulled, the green light comes on the charger when plugged in.

I pulled the lid off to get to the motherboard. Once I unplugged the cable that connects the lid to the motherboard and plugged it back in, I powered the computer on! It was sitting there running, the fan in spinning, great!

I have it up and running for about 8 minutes or so, and then it just shuts off and now I cant get it to turn on again. It properly booted into the OS and I opened up some programs and looked at some options to see if it seemed like it was freezing and it wasnt.

Any ideas on diagnosing this?

anonymous Mac Tech
10-05-2011, 04:00 PM
I pulled the lid off to get to the motherboard. Once I unplugged the cable that connects the lid to the motherboard and plugged it back in, I powered the computer on! It was sitting there running, the fan in spinning, great!

I have it up and running for about 8 minutes or so, and then it just shuts off and now I cant get it to turn on again.

I've seen the exact same thing at least a few times and it has always turned out to be a short somewhere on the board. Its starting to look like this where macbooks go before they die. Might want to check the fan functionality and maybe re-paste the heatsink to make sure it isn't heat related or something. You can also remove any screws that are mounting the board to the bottom case and make sure its not shorting on a screw mount. There are really on three screws that are just designated to hold the board down. the rest are related to brakets, heatsink, fan, etc..

Other than that you may want to try a different top case just to rule that out, but I doubt its going to make much difference.

xxsilk109xx
10-05-2011, 04:44 PM
Ok well I have got this far:

I pulled the fan and all surrounding connections out and re pasted the cpu/gpu. Reconnected everything and started it up. It booted into the os to where I can type the password, now, after i type in the login password, it powers off and then reboots itself.
It also when it reboots, sometimes has no backlight on the screen once it hits the login screen, but retains backlight up to that point....

any ideas?

Wow, I just restarted it and now I am in the OS doing a verify disk check to see if I can get it to shut off again...kind of odd, I guess it is a short but how do you narrow it down?

anonymous Mac Tech
10-05-2011, 09:23 PM
Ok well I have got this far:

I pulled the fan and all surrounding connections out and re pasted the cpu/gpu. Reconnected everything and started it up. It booted into the os to where I can type the password, now, after i type in the login password, it powers off and then reboots itself.
It also when it reboots, sometimes has no backlight on the screen once it hits the login screen, but retains backlight up to that point....

any ideas?

Wow, I just restarted it and now I am in the OS doing a verify disk check to see if I can get it to shut off again...kind of odd, I guess it is a short but how do you narrow it down?

Disk Verify will likely find errors since it is only checking the file system (which is likely hosed with all the sudden shut downs). Have you done the basics like SMU and PRAM resets (not going through explaining them, google if you don't know the terms)? What happens if you disconnect everything but the internal display and power it up (optical, HDD, airport card, etc)? Does it still shut down even when not booted to anything? Any signs of liquid corrosion on the board?

xxsilk109xx
10-06-2011, 02:15 PM
Finally got it working. I booted to a the OS disk and there were many disk problems, so it fixed them and it has seemed to be operating normally since.

I got it to start acting normally after i disconnected just about everything and plugged it all back up. I think it was just a short somewhere, but I am going to keep it in shop and run some further tests on it.

I came in this morning and it was not plugged into the wall and was running on battery power and I opened the lid and it woke up normally.

anonymous Mac Tech
10-06-2011, 05:48 PM
Finally got it working. I booted to a the OS disk and there were many disk problems, so it fixed them and it has seemed to be operating normally since.

I got it to start acting normally after i disconnected just about everything and plugged it all back up. I think it was just a short somewhere, but I am going to keep it in shop and run some further tests on it.

I came in this morning and it was not plugged into the wall and was running on battery power and I opened the lid and it woke up normally.

Could be the directory structure was that hosed that it was shutting down. Usually in those cases it won't fully boot up. It will get the grey screen with Apple and spinning gear and shut right down. But again, the shutdowns could have been what hosed out the directory structure in the first place.

kevinjhaag
10-07-2011, 03:02 AM
Very interesting to hear what fixed it. I was leaning more towards a faulty logic board or short somewhere. I would check the hard drive for bad sectors. I would think that it would have some. In that case I would just change the drive out. Great Job though!