820-3332 Short to ground on ppbus_g3h

RavetcoFX

New member
No liquid damage, originally was having troubles turning on and was producing a clicking sound, now the clicking has stopped and the short appeared, still getting orange light, ppv5_S5 is 1.1v not sure what to do now. I created this new thread since it's a new issue than the original posted
 
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RavetcoFX

New member
Yeah, so I'm also getting short to grounds on PPDDR_S3_REG, PPCPUVCCIO_S0_REG_R, PPVCORE_S0, and PPVCCSA_S0_REG_R, but some of them are low voltage, so I don't know if that's normal, I'm also not familiar with what a FET being low side and high side means.
 

dukefawks

Administrator
A short on PPDDR is not good. How low is resistance to GND on that bus?
Look at Q7330 it's a dual FET. The top one is the high side, it runs from the "full" PPBUS power to the "low" voltage output. If it shorts there is a direct connection from the 12.6v PPBUS to the RAM.
 

RavetcoFX

New member
So that's neat, going back to test, ppddr_s3_reg is now getting ~330ohms resistance to ground when before I was definatly near 0, but pppchvccio_s0_reg is 24ohms to ground, PPCPUVCCIO_S0_REG_R is 16ohms, PPVCORE_S0 is 4ohms, and PPVCCSA_S0_REG_R is 11ohms. Q73330 looks right as rain
 

dukefawks

Administrator
So you have no "full" short on any coils, that is good at least.
What is resistance on PPBUS though? If it matches any of the coils you measured you probably have a shorted high side FET on that bus.
 

RavetcoFX

New member
Resistance on PPBUS is around 4ohms, which matches the resistance on the CPUIMVP_PHASE* busses which would lead me to believe that its the MAX15119GTM, but it's not producing any heat. So then I went around with my laser temperature gun, narrowing down with evaporating alcohol to find ISL6259HRTZ is hot as shit meaning that's it's the thing shorting to ground, but would this also cause the CPUIMVP_PHASE* stuff to do so as well, and would this chip have been able to make the clicking sounds?
 

dukefawks

Administrator
Measure from PPBUS to PPVCORE_S0 and see if resistance is 0, then you know you have a shorted high side FET on that bus. The 6259 is probably dead too, but need to check PPVCORE first.
 

RavetcoFX

New member
Alright, sorry for taking so long, I finally got in a bunch of different donor boards which I needed.

So I started off replacing the ISL6259 as well as C7040 since it didn't look happy, and then replaced Q7035 since it was causing a short to common on CHGR_LGATE

I did test the resistance between PPBUS_G3H and VCORE_S0_CPU, and got ~4ohm resistance, and resistance with PPBUS to common is ~3ohms, is this about right?
 

dukefawks

Administrator
3 ohms to GND on PPBUS is a short of course. Time to inject voltage and see what heats up. Start off low with 2V and monitor current.
 

dukefawks

Administrator
A dead motherboard that still powers on. Use the CPU Vcore power supply to get a 1V high current power supply.
 
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