820-00923 Missing CPU-VCORE

[Kappy]

Liquid damaged 820-00923 using 820-00293 Schematics and BV. I have all rails present apart from the following :

PPVCC_S0_CPU
PPVCCGT_S0_CPU
PPVCCEDRAM_S0_CPU
PP0V6_S0_DDRVTT

I believe the last 2 won't have any voltages until the top 2 are working.

Both the top 2 come from the U7100

I've check the U7100 and I have:

SDA - 1v
SCLK - 1v
ALL_SYS_PWRGD - 3.3v
CPUVR_PGOOD - 3.3v
both VIN & VCC have the correct voltages.

For shit's and giggles I change the U7100 this didn't make any difference.

Next I've looked at the U7210, U7220, U7410, U7420 & U7430

All of them have 2.5v on the PWM line, 0.00v on the FCCM line and the correct voltages on VCC, VIN, PVCC.

On U7270 (PPVCCSA_S0_CPU) which is working. I get 5.0v on both PWM and FCCM and Vout of 1.02v (schematics says Vout 0.55 - 1.15v)

So maybe with PPVCCSA_S0_CPU working and with all Vin voltage present this rules out the U7100.

Initially as mentioned this was liquid damaged and had a short to ground on the U7210 which was causing PPBUS to short. I changed this and now I have all the power rails.

Not sure what to check next.​

 

[Kappy]

How long do I have to wait until I get a response to my problem?

 

[phuketmymac]

Where was the liquid damage located first?

 

[dukefawks]

U7210 was shorted putting PPBUS straight to the CPU. CPU was instantly killed, this board is done sorry.

 

[Kappy]

$29 for you just to come to that a assumption without even asking me any readings!

 

[JohnB8812]

It’s a high side mosfet it’s going to pretty much always kill what’s on it line.....Jesus lmfao he’s just being honest...

 

[dukefawks]

There is nothing to measure, the CPU is 100% dead once PPBUS got to it. Be glad I told you, you could have wasted many more hours on this.