Apple MagSafe 820-2627-A

[Elrod]

I recently had to repair my daughters aging Macbook(A1342).   It would no longer charge so I opened it up and found a burned SMD package on the small MagSafe PCB where the power enters.  These are easily available online so I ordered one but was also curious what was on the small PCB.  There are schematics available for the main logic board of the Macbook  but I could not find a schematic for this small PCB anywhere.  I have drawn out what I found and will post here in the hopes that someone else might find it useful.  The part number on the PCB is 820-2627-A.

[Wirehead]

How about a picture of the burnt area

[Elrod]

How about a picture of the burnt area

Ok. No problem.  D1 had burned/shorted.  I removed it to so that I could determine what trace went where with my ohmmeter.  I still had trouble because I kept having low resistance readings to the chassis ground.  Finally determined that the PCB was charred beneath D1.  I had to dig out the charred area so that I could continue continuity checks without the leakage path through the PCB.  So that's why there is a hole there.

[Wirehead]

The big question is, why has that diode gone up in smoke? If it failed by itself, you could hack up something to work around the charred area. If it's "upstream" you might run in to the same issue again. So make sure you check that as well. Cheap fix would be to snag one of these board from ebay or the likes.