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820-01041 missing S5 rails

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tcampbell34

Member
I have a 820-01041 board that has minor liquid damage on the U3200/U3100 side of the board. I was getting only 5v on the charger and 450ma, which is high. I replaced U3200 and U3100, but still had 5v 450ma. I checked the board on thermal, and saw U9580 was getting hot. Replaced U9580 and got 20v, but all my AWAKE and SLPS2R voltages were pulsing. Checked on thermal again and saw U7660 was getting warm. Replaced U7660 and U7650 and now I have steady voltages on all my rails up until S5. I am missing PP3V3_S5 and PM_SLP_S5_L. I tried T2 firmware restore and it is recognized in DFU mode, but quickly fails and produces an error. Does this mean the PCH is at fault, or is there something else I should check first?
 
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tcampbell34

Member
I checked diode mode to ground on all the SSD rails and they all match against my working board, so not convinced its a SSD issue. My previous post was incorrect when I said I have steady voltages up until S5. I now noticed that all my AWAKE and SLPS2R voltages still pulse, but they stay steady for about 20 seconds and then pulse, so I was not holding my probe there long enough to catch the pulse. PPBUS is 12.6v for 20 seconds or so, and then drops to 12.3v for about 2-3 seconds and then goes back to 12.6v. No pulse on PP3V3_S5, but PP5V_S5_LDO is 5.13v and the pulses down to 5.02v when PPBUS drops. I cannot find any shorts or anything heating up abnormally on thermal, so not sure where to check next.
 
2informaticos

2informaticos

Administrator
Staff member
If AWAKE and SLPS2R voltage are not stable, that's the reason T2 cannot complete DFU.

When PPBUS_G3H drops, what happens with 3V3_G3H?
USB_C meter shows steady 20V at same time?
 
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tcampbell34

Member
3V3_G3H stays steady at 3.3v the whole time and the meter shows 20v still but the amps do drop down at little when PPBUS drops.
 
2informaticos

2informaticos

Administrator
Staff member
12.6V is the nominal PPBUS_G3H.
If drops to 12.3V means SMC lose the communication with U7000 somehow.
There can be an issue with battery bus.
I recommend to test with known good battery; not new chinese one.
 
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tcampbell34

Member
I tried with a known good battery and PPBUS pulses from 11.6v to 12.3v, with the charger connected. Without the charger and just the battery connected, PPBUS seems to be steady 11.2v.
 
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tcampbell34

Member
Diode mode values seem to match another board. With both battery and charger connected, SMBUS_3V3_BATT_SCL is 3.3v, but pulses down to 3.2v. SMBUS_3V3_BATT_SDA is 3.3v, but pulses down to about 2.7v. With just the battery connected, they both seem to be steady 3.3v. I can try and replace U7000 and report back
 
2informaticos

2informaticos

Administrator
Staff member
Seems to have communication on the battery bus, as you've noted pulsing down; you can check it with o-scope.
If battery and U7000 are good, there remains T2 as suspect.
 
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