820-00138-A Shuts itself down before booting to system.

[Beto_MFC]

Replaced U7200 (CPU VR12.5 VCC Regulator IC) and caps C7210, C7211 and C7212. After that, system doesn't power off but I get no vCore. CPU cold as a corpse...

 

[dukefawks]

You screwed up U7200 or something else.....I can't help with this one any further sorry.

 

[Beto_MFC]

Just swapped a cap and a resistor by mistake. Very hard to solder 0201 components without microscope. Will fix and get back here. It will be the first time with the replaced U7200. But that error made me have sure that is the U7200 circuit or some cpu feedback that is making it turn off.

 

[Beto_MFC]

Ater I swapped all 3 phases of the CPU VCC regulators, it won't turn on. I noticed that the inductor L7130, which is for the battery charger gets hot when ac connected. Can I blame a bad CPU yet and discard this repair?

 

[dukefawks]

Yeah 12V has now gotten to the CPU, this is trash now.

 

[Beto_MFC]

Don't think so. If anything, this board doesn't get vCore at all. After the last VCC regulator swap it stopped working, Will give it a last try as the inductor has nothing to do with the 5v rail that power the CPU.

 

[Beto_MFC]

Confirmed. Pulled off U7310 and it worked again same way as before (turn on then off after some time). One phase of the CPU got fried. Destination: Trashbin.