820-01041: Wondering if there any schematics or sub for this.

Hello,

I was wondering if there any schematics or version that will work for this board (820-01041)? I'm troubleshooting no power, PP20V_USBC has 5V. PP3V3_G3H_RTC has 0.8V. I check for shorts and found none on that line. But without a schematic, I'm a bit lost as to where to go from here.
 
is there a way to safely induce power on the PPBUS_HS_GPU line to see which device gets hot? Was wondering if I pull R5400 to isolate PPBUS_G3H, if this will be fine. Only other option is to start pulling all the parts tied to the line, which are a lot.
 

2informaticos

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Post exact value (ohm scale) for PPBUS_G3H to ground.
Then check if any big coil has similar value.
If yes, measure ohm value between that coil and PPBUS_G3H.
Then you can see if corresponding high-side MOSFET is shorted.
If is one from CPU power supply, you can fry the CPU injecting voltage, before removing that MOSFET.

BTW, so many time explained on the forum how to proceed about this issue...
 
PPBUS_G3H - 1.11
L7231, L7221 and L7211 measure 1.11
Measured from coils to PPBUS_G3H - 0.71.

So pulled all 3 MOSFET. The coils now measure 1.3. Not much change. Went ahead and replaced all 3 MOSFETs and now I have 20V power but no current draw. None of the big coils have power on them.

PPBUS_G3H is no longer shorted. Readings in the mega ohms
 
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3V3_G3H - 3.39
PPBUS_G3H - 12.6
UPC_PMU_RESET - 0
PMU_ONOFF_L - 3.3
PMU_RSLOC_RST_L - 3.3
PMU_RSLOC_RST_L - 3.3
PP3V3_G3H_RTC_X

UPC_PMU_RESET does have about 1.4mV while CHGR_RST_IN_R has exactly 0. Not sure if this means anything.
Unfortunately, if it's U6940, I still haven't been able to find replaces or substitutes for this chip.
 

2informaticos

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I was thinking reset should be high, like in other old boards.
But in fact, missing "_L" from the end should mean 0V is correct value.
Is the second time when saw this and probably is correct.

Check if PM_PWRBTN_L reacts when trigger PMU_ONOFF_L signal.
Use SWK000/002 for test.
 

2informaticos

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Check PCH's RTC signals at page 12.
Also check PCH_RTC_RESET_L.

You forgot to post PP3V3_G3H_RTC_X value.
Is U6940 powered?
 
Do you mean signals with RTC in the signal name? On page 12, the 3 signals I type were the only RTC signals. But here are all the other RTC signals for the PCH.

PPDCPRTC_PCH - 1.16
PP3V0_G3H_RTC - 3.0
PCH_INTRUDER_L - 2.5
 

2informaticos

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PMU (U7800) and T2 chip (U3900) are both involved in the startup sequence.
I didn't get any machine with T2 in my hands yet.
Still need to find all signal levels required.

What about PM_RSMRST_L and PM_BATLOW_L?
 
PM_RSMRST_L - 0
PCH_BATLOW_L - 0

so did some reading on the T2 chip and I?m thinking this board my be bricked. But there is so little info out there regarding T2 chip boards that had parts replaced.
 

2informaticos

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Check some voltages and signals for PMU.
PP3V3_G3H_PMU_VINRTC_R
PP3V3_G3H_SOCPMU
PMU_PVDDMAIN_EN
PMU_ACTIVE_READY
LDO_CORE/RTC
PMU_LDO3_OUT
PP3V0_G3H_RTC.
 
PP3V3_G3H_PMU_VINRTC_R - 3.39
PP3V3_G3H_SOCPMU - 3.36
PMU_PVDDMAIN_EN - 3.39
PMU_ACTIVE_READY - 1.8
LDO_CORE - 1.5
LDO_RTC - 1.5
PMU_LDO3_OUT - 1.8
PP3V0_G3H_RTC - 3.0

also checked SOC_XTAL24M_IN from U3900 and only getting 540mV, no signal. Should be 24MHz

PP3V3_S5 - 0.0
 
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2informaticos

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"PMU_PVDDMAIN_EN - 3.39"
So you should have voltage at L7660; check it.

"PMU_LDO3_OUT - 1.8"
I think this must be 3V.
In such case, U7800 could be bad.
 
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