820 4924 missing s4

[EJS]

820 4924 no power, no water damage, green light on mag safe 12.59v PPBUS g3h, 5v pp5vs5, 0v pp5vs4, 0v p5vs4_en.

 

[dukefawks]

Any history? Checked all rails for shorts?

 

[EJS]

CPU VCORE is shorted, is it safe to inject voltage into this line to find the short, or am I going to kill the CPU?

 

[dukefawks]

Define "shorted", need resistance in Ohm. Do not inject anything on Vcore!

 

[EJS]

13.2ohms on CPU VCore

 

[dukefawks]

That is not shorted, but it is a bit low. Is 3V present on L7560? Carefully check for power cycling on L7520, preferably with a scope as multimeter may be too slow to catch the pulse. PPVRTC present?

 

[EJS]

3.34v @ L7560
0v on L7520 cant see a cycle with Fluke, sorry no scope
3.34V on PPVRTC

 

[dukefawks]

Was this thing already messed with by someone else. These do not "just" fail like this very often, I really want to know is there is any back story.

 

[EJS]

I contacted the owner this morning, he said nothing happened more than the machine died in use. I've looked this board up and down, and I can confidently say that no one has messed around with this board before.

 

[dukefawks]

Ugh, that 13.2 on Vcore is kinda low. Do you have a board to compare? This may well be a dead CPU

Also you say green light on charger but this must turn orange in all cases, please confirm that. Also some of these boards seem to need a working battery to turn on, is SMC_ADAPTER_EN present?