SMC / power / charging circuit problem

"At this point I suspect the charging circuit is in trouble (on the logic board).

There are a few MosFET's and a comparator logic that often get burnt. Often you can see them damaged. Look right behind the battery connector there you will find 2 four pin MosFET's (with a larger fifth pin on the other side).

Update

The SMC is a micro-controller that gets the input from the comparator logic.

Sure, its possible the SMC is damaged as well. But, you need to work upto it from the battery & charger circuit. I don't remember seeing the SMC fail with all of our systems.

Static is the the big killer here. One thing we've discovered is the carrying cases we had used would discharge into the MagSafe connector when the laptop was put in or out.

Also with the colder weather moving in, the air gets dry so its also important to be doubly careful when opening systems (using ESD safeguards).

As to testing MosFET's:

Testing out of circuitTesting in circuit

On the most part unless you have the tools, skills and access to the parts this is something you should hand over to a person with SMT skills."

"I ran across this thread while looking for other things and thought I could add something that could help the original poster or anyone in the same situation. Rather than typing the explanation and how to fix this problem, which I don't think is as serious as you may think... I am going to provide a youtube link for something very similar.

This thread is a little old but seems to not have been fully answered or resolved so I am going to try to add something.

https://www.youtube.com/watch?v=FLH2Ns7Z...

Assuming this computer is still in the same condition as before, there is an important 3.3V power supply that must be present on the board for the charger and everything to activate correctly. This power supply is responsible for providing power to something called a one-wire circuit which allows the SMC to communicate with the battery and charger. Before power will be allowed into the computer (assuming you have not done the SMC bypass) some conditions appear to have to be satisfied including communicating with the charger and battery.

This 3.3V power supply (more like 3.5V) is actually on all the time even when the computer is powered off. As in the video above, you should check this power supply, assuming you have access to the board schematics and board layout, and it may be something as simple as a single resistor or fuse that went out that is preventing this power supply from turning on and therefore disallowing ever other power rail in the system from being turned on."

You shorted the battery terminals to the data line terminals. Hello 12 volts to the SMC data line, fix pins and replace SMC because it is toast, along with your battery indicator LED>