I would like some help with this MacBook if possible. It came in with not turning on and the Magsafe light was off. After inspecting the logicboard i cannot find any liquid damage and also no burnt or shorted components.
took some measurement and i can see i have fluctuation on PP3V3_S2 and also PP5V_S2_MAIN amongst other rails. Using the thermal camera RC282 & RC283 were pulsing, but after removing these it was still the same.
I then did some investigation into why the rails were pulsing and noticed that P5VS2_PWR_EN (comes from U8100) is also doing the same thing.. Replaced both U8100 and also U7700 from a working (iCloud locked) logicboard, still the same. I've also temporarily removed all the components on the PP3V3_S2 rail but the fluctuation is still there so i'm thinking that it could be coming from a higher rail. I'n not sure what the power rail startup sequence is on this model. All the AON rails are fine and stable and now i've hit a wall and not sure what to do next.
took some measurement and i can see i have fluctuation on PP3V3_S2 and also PP5V_S2_MAIN amongst other rails. Using the thermal camera RC282 & RC283 were pulsing, but after removing these it was still the same.
I then did some investigation into why the rails were pulsing and noticed that P5VS2_PWR_EN (comes from U8100) is also doing the same thing.. Replaced both U8100 and also U7700 from a working (iCloud locked) logicboard, still the same. I've also temporarily removed all the components on the PP3V3_S2 rail but the fluctuation is still there so i'm thinking that it could be coming from a higher rail. I'n not sure what the power rail startup sequence is on this model. All the AON rails are fine and stable and now i've hit a wall and not sure what to do next.
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