For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
Something is giving 12V on pin 3 in Q8400, and I am assuming there should not be 12V. I removed the R8402 just to make sure it's not complicating this. Do you know what should be my readings on R8401 or C8400 on ( pins 2 ) since they are connected to pin 3 of Q8400. I am guessing they should not give 12V
Not really. I am suspecting weird behaviour from Q8400 now. Since some time ( as mentioned before ) it had 12V on both 3,4 pins. I suspected some short before and removed it but then when soldered back all of the surrounding components it was the same. I am looking at the schematics and trying to remove possible sources of power that might be getting to it. I removed now C8400, C8401, R8401, R8402. When I measure voltage I can see now 12.9V on pin 4 and about 7V on pin 3 ( Q8400 ) - is that "normal" ? I would expect 0V at this point on Q8400. I am suspecting now that voltage on pin 3 is getting from pin 4. Can I test it if it's bad ? Would a picture of a broken pad of R8402 help ?