Chosen Solution
Thanks for reading this post. I’m working with a 2015 rMBP 13" that has no power to the logic board and no magsafe light. I’ve already confirmed the DC-in board is good as it tested fine on another unit. LB has already been ultrasoniced. It seems resistor “470” was blown as well as “100” above it. I replaced both and gave it a try and 470 blew again. Does anyone know what would cause this and where else to look and what else to try? Appreciate all the help and I’ve learned a great deal from this site already. Update (11/25/2017)
Here’s an image I found, it doesnt show them blown but you can see about the two I’m talking about.
Just a quick update/answer on this. I ended up sending this to a “more knowledgable” repair company and they sent it back as a no fix saying the CPU was shorted. Not sure how that made any sense so I decided to try to tackle it myself. Measured voltage after R7020 after I replaced the 3 caps on the PPDCIN_G3 rail and it was jumping quite a bit (anywhere from 16-19v). No magsafe light. After testing the magsafe voltage to make sure it wasn’t an adapter issue I decided to replace ISL U7100 (the charging IC). That did the trick and it seems to be fully functional.
@bkoosy this is not to diagnose your logic board but to identify the components you inquired about. The part with the marking 470 is reference designator R7020. It is a 47ohm 1% 1/3Watt resistor in a 805 package. The component with the “100"marking is reference designator R7005. That is a 10ohm 5% 1/8Watt resistor in a 805 package. Both components are part of your DC-in and battery connector circuitry. R7020 is part of the PPDCIN_G3 rail so you would have to test the components along that rail to see why and where it shortens out. You will need to obtain the schematic and boardview for the 820-3536 logic board in order to check those rails.
