Macbook restarts itself only when plugged in to power

Hello everyone,

I am new to this forum so forgive me if this has been asked before. I have searched but I can't find an answer to my problem anywhere.

Here is the scenario:

I have a Macbook 3,1 Late 2007 edition with 2GB RAM and a 250GB HDD, CPU Intel Core 2 Duo 2.2Ghz. I bought it used and I bought a non-Apple Magsafe adapter. All was fine for months but now for some odd reason it reboots itself shortly after I login and it only happens when it is plugged in with the magsafe adapter. It does this from MAC OS X and Windows 7 on my BOOTCAMP partition.
If it runs on the battery, it has NO problems and it stays on until the battery is depleted.

What I have tried:

I tried to reset the PRAM no success.
I tried to reset the SMC by pulling the battery out and holding the power button for 5 seconds no success.
Thinking that it was a bad power adapter, I borrowed another one from a friend and no success. Problem still persists.
The only thing I have done last was to upgrade the hard drive from the factory default 160GB 5400RPM to a 250GB 7200RPM.

I have also tried to download the latest SMC firmware but all of them show a message "It is not needed on this computer" when I try to install.

Any other ideas what else it could be? It is driving me nuts!!

Thank you for all your help.

Joe Matarazz

You said that you bought a non-Apple Magsafe adapter; was your friend's adapter an Apple Magsafe?

If so, you might have a bad power supply.

josephmccutchen said:

You said that you bought a non-Apple Magsafe adapter; was your friend's adapter an Apple Magsafe?

If so, you might have a bad power supply.

Click to expand...

Yes, my friend's adapter was an original Apple Magsafe and it did the same thing. Booted into MAC OS X and shortly after, the screen goes suddenly black and then it starts up like I just powered it on.

Here is an interesting extra piece of information. I pulled the battery out (Also a non original Apple) and left the laptop powered on with the non Apple magsafe. It seemed OK for a while. I then put the battery back in and booted in single user mode and left it alone for a while. No problem, no reboot.

I re-seated the memory just for kicks and it hasn't rebooted so far. I will keep it on that way some extra time today...

Don't think it is the power adapter since it did the same thing with a Apple and non Apple type.

Hmmmmm...... Perhaps it's a bad battery? You could try swapping batteries and see what happens then. I would try that. Also, if you have easy access to your friend's adapter, you could using it w/o the battery, and see what happens.

josephmccutchen said:

Hmmmmm...... Perhaps it's a bad battery? You could try swapping batteries and see what happens then. I would try that. Also, if you have easy access to your friend's adapter, you could using it w/o the battery, and see what happens.

Click to expand...

Interesting isn't it? I actually have had it running for an hour with the adapter and battery that were giving me the problem. Now here is the diff. the battery shows 100% changed and it is not charging. I will let it run on battery for a while and then plug the magsafe in. If it reboots, I think you may be right. The battery causes issues when charging. Will post soon....

MacBook late 2007; that's what I used to have. If it is the battery that's causing the problem, at least it's easy to replace! i have a mid-2010 MacBook Pro unibody; no, the battery isn't hard to replace, just a little more work, and Apple saying don't do it. Looking forward to your post as to what happens!

Wow, now I am even more confused than before. I let the battery discharge to 50% and the plugged in the Magsafe adapter (non-Apple one). The macbook has been running for the past hour, I ran updates, installed stuff, etc. Still ON.

I guess it boils down to 2 things: 1) Re-seating the memory modules. or 2) Re-seating the battery (non-Apple).

For general information: Sudden reboots are usually caused by one of two things: Bad memory, or power supply. So perhaps you've zeroed in on the problem.