(347) 552-2258 help@rossmanngroup.com

820-00244 No boot, PPBUS_G3H initially present, voltage slowly drops

M

macdude101

New member
820-00244 here, doesn't boot. 20V from USB-C charger but no current.

No S5 through S0 power rails.

PPVBUS_LIO, PPDCIN_G3H, PP3V3_G3H and PP3V3R3V0_AON all present and correct.

PPVIN_G3H_P3V3G3H 20V but should be 8.6V according to schematic?

PPBUS_G3H should be 8.6V but starts at around 8.2V for 1 second after power input before slowly dropping to ~0.7V. PPBUS_S5_HS_COMPUTING_ISNS looks similar.

PPVRTC_G3H 0.5V then slowly drops, should be 3V.

PP5V_G3H 0V, not present at all.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Looks like you have a problem with U7800; it generates both 5V_G3H and RTC voltages.
Check first diode mode to ground at PPVRTC_G3H and PP5V_G3H.
If nothing low, then check SMC_PM_G2_EN and PP3V3_PMICLDO.

Any history available, liquid signs?
 
M

macdude101

New member
PPVRTC_G3H diode mode OL, good: OL.
PP5V_G3H diode mode 1.94V, good: 1.93V
SMC_PM_G2_EN is 3.3V.

PP3V3_PMICLDO 0V, should be 3.3V.

No history known, no sign of corrosion but there was a thin layer of dust/fibres on the board when it was first received.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Looks like you measure in wrong way.
ALWAYS start measuring diode mode with red probe at ground.
Sometime (rarely) need to invert the probes, for the other reading.

Now check diode mode at PP3V3_PMICLDO too.

BTW, you MUST check PP5V_G3H and PP3V3_PMICLDO voltage at the moment when PPBUS_G3H is high (8.2V).
Same for PMIC_SHUTDOWN_L...
 
M

macdude101

New member
D'oh!

PPVRTC_G3H diode mode 0.445V, good: 0.452V
PP5V_G3H diode mode 0.458V, good: 0.457V
PP3V3_PMICLDO diode mode 0.417V, good: 0.417V

And good point re. checking those whilst PPBUS_G3H is still high, only had a couple seconds to do it but useful find:

PP5V_G3H 5V then drops to 0V after 1-2 seconds
PP3V3_PMICLDO 3.3V then drops to 0V after 1-2 seconds
PMIC_SHUTDOWN_L 0V then 3.3V after 1-2 seconds
PMIC_SHUTDOWN_L 3.3V then 0V after 1-2 seconds

So I assume this suggests it's powering on very briefly but immediately shutting itself down. Trying to understand that. I see PMIC_SHUTDOWN_L is created from PP3V3_PMICLDO?
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
"PMIC_SHUTDOWN_L 0V then 3.3V after 1-2 seconds"
That can be true, if PP3V3_PMICLDO disappears.
Be sure to check in proper point.

Also PMIC_SHUTDOWN_L MUST be high, to enable the rest of U7800; at same moment when the other mentioned voltages are present.
 
M

macdude101

New member
Measured them all at the same moments after turning power on.

And that's my bad, I typo'd that, PMIC_SHUTDOWN_L starts at 3.3V then drops to 0V after 1-2 seconds at around the same time as PP3V3_PMICLDO does.
 
2informaticos

2informaticos

Administrator
Staff member
OK, that make sense now.
If you get 20V on USB-C meter, SMC is running.
But seems that it doesn't properly communicate with U7000.
U7000 itself can have problems, or detects something wrong on the secondary rails.

But PPVRTC_G3H should get 3V at first moment and you only get 0.5V; that makes me doubt about U7800 first.
 
M

macdude101

New member
I just re-checked PPVRTC_G3H and it does actually start at 3V then drop to ~0.5V after 1-2 seconds.

Hmm. I wonder then if U7000 is detecting something wrong.
 
Last edited:
M

macdude101

New member
Checking some of the power rails connected to U7000.

PPVIN_G3H_P3V3G3H starts at 8.2V then jumps to 20V after 1-2 seconds. This is meant to stay at 8.6V?

PPDCIN_G3H starts at 5.2V then jumps to 20V, as expected, after 1-2 seconds.
 
Last edited:
M

macdude101

New member
No change in SMC bypass mode, still draws no current when it changes from 5V to 20V on the USB meter after releasing SMC_ONOFF_L.
 
2informaticos

2informaticos

Administrator
Staff member
Check for pulse at all secondary voltages, in the first seconds.
What happens with PPBUS_G3H when connect both battery and charger?
 
M

macdude101

New member
PP5V_S5 0V, pulses to 4/5V, drops and settles at 1.1V
PP3V3_S5 0V, pulses to 1/2V, back to 0V
PP5V_S4 0V

S5_PWRGD 0V
PM_SLP_S5_L 0V, pulses to 0.2V, returns to 0V
ALL_SYS_PWRGD 0V, pulses to 0.2V, slow drop to 0V

With battery connected PPBUS_G3H behaviour is mostly the same but somewhat more staggered 8.2V -> 5V -> 3.6V then slow drop to 0.7V. Whereas disconnected it's just 8.2V then a slow drop (without jumps) to 0.7V.
 
M

macdude101

New member
Testing with diode mode, reading vs known-good(s)

PP5V_S5 0.445V 0.45V
PP5V_S4 0.160V 0.163V
PP5V_S0 0.576V 0.576V
PP3V3_S5 0.382V 0.380V
PP3V3_SUS 0.366V 0.367V
PP3V3_S4 0.443V 0.442V
PP3V3_S0 0.370V 0.371V
PP1V8_SUS 0.425V 0.422V
PP1V8_S3 0.424V 0.454V
PP1V5_S0 0.444V 0.446V
PP1V2_S3 0.160V 0.203V 0.289V
PP1V2_S0SW 0.160V 0.203V 0.290V
PP1V2_S5SW 0.361V 0.361V
PP1V_SUS 0.275V 0.247V
PP1V_SUSSW_HSIO 0.275V 0.248V
PP1V_S3 0.293V 0.249V 0.268V
PP1V_S0SW 0.322V 0.296V
PPVCCIO_S0 0.198V 0.185V
PPVCCSA_S0 0.093V 0.097V
PPVCORE_S0_CPU 0.03V 0.027V
PPVCORE_SUS_PCH 0.348V 0.260V

PP1V2_S3 and PP1V2_S0SW are looking off. PP1V2_S0SW looks to be created from PP1V2_S3 though so that makes sense.
 
2informaticos

2informaticos

Administrator
Staff member
You've got big difference even between working boards, so the readings on 1V2_S3/0 may not help too much.

Maybe need to chabge U7000 first and U7800 if still the same symptom.
Think if this board worth the job.
You may finally have dead CPU, or SSD.
 
You must log in or register to reply here.
Top