820-3115 no CPUVCORE?


New member
Hello masters I got a board with a short to ground on 3.4v I inject 3.4v and find out u7000 was getting hot , I replace it and short gone , I got back green light and after a few fixes PPBUS_G3H works also , after several diferent replacement of parts I got the machine to power on fan spins I test the board and I find out no chime or display then I when to check resistors R7403 and and R7402 and I have good voltage on pin 2 of booth =PPVIN_S0_CPUIMVP is ok but on the other side of resistors I have .5v on each they match ohms on schematic , and I desolder one side to separate the resistors from pin 1 of the board , and now I find out voltage go just fine on each side of resistors when they have no link to U7400.

What should be my next step?


Could be anything. Vcore is enabled through SMBUS to U7400. If at any point the PCH/CPU do not start up right there will be no Vcore. Only advice I can give is to check for corrosion everywhere. Could be some crap under PCH, corroded trace/resistor, anything!


New member
Hi master duke , ok on L7520 I have 1.2v on L7510 I have 1.2v but... on L7550 I have 0v on CPUIMVP_PHASE1G I have 0v that suppose to go to pin 4 of Q7550 , I replace U7400 voltages are the same before replacement and after replacement , pins 3 and 4 have voltage on Q7550.

I don't know what other info I can get?

But I have a question without
=PPVCORE_S0_AXG_REG I don't get any chime?


Staff member
Was the liquid on the edge?

If there was serious damage to the U7000 area and it went down layers into the board, you're fucked.

If it was on the edge you may be lucky with just corrosion under the PCH.

PPVCORE_S0_AXG is for integrated graphics. Ignore that for now!


I guess the firt problem is SMC, it should not get hot..
CPUIMVP_PHASE1G = PPVCORE_S0_AXG_REG, if you dont have internal screen attached it wont come up, it needs detect screen first, but now this does not matter because you dont have the chime ..
If everything is ok you should have chime, does not matter if you dont have PPVCORE_S0_AXG_REG aka does not matter if you dont have a screen attached....
In fact you have PPVCORE, but when it works perfect, 1.2V should go a bit down to about 0.9V.....
Check SMC, maybe water damage around, i guess you need to replace it....