ATTENTION: Opening the AC adapter means you are voiding the warranty provided by Apple. In case of any accidents, fires or mishap, you will hold me harmless against all liabilities, lawsuits, etc.
Work Steps that I’ve taken
Disassemble the adapter by opening it with pliers. You will need a bit of strength to open the adapter. DO NOT to whack the adapter against any hard object in hopes the glue will give way. IT WILL NOT.
This is how I opened the casing.
This is the aftermath of removing one half of the cover.
The green strips are 3M tape to hold the copper shielding together. Depending on the position of the soldering connectors, you might need to remove the copper block from the white plastic casing.
In my case, the casing opened on the wrong side (the soldering connectors were only accessible from the other half of the casing), so I had to remove the other white casing to get to the connectors.
How would you know which is the correct side? Look for the orange tape.
You will need to remove the orange tape to get to the soldering connectors. Above shows the white casing opened from the wrong side, thats why I had to remove both sides of the casing.
Before cracking open the other side of the casing, you will need to be careful as the other side will connect to the external connectors.
By the way, the white gunk appears to be the glue. I’ve gently scraped them away as it’s hindering the adapter refitting into the casing.
Unlatch the copper shielding on the side with the orange tape.
Then you will get to the circuitry after lifting the inner copper shielding. Depending on your soldering skills, a 75 degree bend on the inner copper shielding should be more than sufficient to get to the two soldering points.
Remove the orange tape, it should be out with a slight pull. Do not remove the white gunk blob between the green and black wires.
So we are ready to desolder the two points. The point on the left (green wire beneath) belongs to the positive terminal. The point on the right, leads to a black wire, for a negative terminal.