820-01700 No Power, PP3V3_S5 missing.

[Sergio Kub]

820-01700 No Power, PP3V3_S5 missing.
I think the board doesn't turn on.
I have power on directly on the board in SWK001
External power supply with digital volt/amp and shows 20V and 0.350A.
LDO Voltages Ok

[Sergio Kub]

I checked this voltage sequence and it stopped at PP3V3_S5

[mon2]

With no power to the board -> measure the resistance to ground of PP3V3_S5 (created by U7800, N10). What is the resistance to ground ?

[Sergio Kub]

18.2 K Ohm... measured at R9802 (1)
Is there an enable for this source on this IC?

[mon2]

See attached. The enable will be from step # 1. What is the voltage to ground @ #1 stage ?

This is the PMU_ONOFF_L signal.

Review the power button pads to mimic the ON/OFF power button.

[Sergio Kub]

Measure the outputs of the IC (U7800) and all with high resistance.
The lowest resistance outputs were B1 8.7 Ohms and L16 47.5 Ohms, which I think is ok

[Sergio Kub]

The board does not turn on
PP3V3_S5 and PP1V8_S5 missing
I put the board in the computer and checked that the Power key was working.
If I keep the power key pressed for about 5s the current goes to 0A on the external source.
I didn't find a short in these sources.
I observe strong heating in the U9300 and U 9200 by around 55ºC.
I don't have much experience with this 820-01700 board, but it's strange

[Sergio Kub]

I will try to turn on the power and simultaneously inject 3V into the output of the U7800 and observe the electrical current

[Sergio Kub]

Could anyone get me the block diagram of the power sequence for this 820-001700 board?
There is no such page in my schematic.
The board has changed the nature of the problem a little... Now it turns on the initial sources and turns them off.
I suppose there is a short in a secondary source S3, S0...
With the source connected, it produces 20V and the current varies from 0 A to 0.5 A in approximately 10s
By pressing the power button, the fans rotate and the current goes up to 2.5 A and returns to 0 A

[mon2]

What is the voltage to ground of ppbus_g3h?

From Rossmann forum:

Remember that this machine requires 96W charger to boot; if no good battery connected.

[Sergio Kub]

ppbus_g3h 12.65V
discharged battery. The power supply I am using is 65W.
Q7065 (G) CHGR_BGATE = 12.65V - PPVBAT_G3H_CHGR_R (S) 12.65V - PPVBAT_G3H_CONN = 0V.
I will order another new battery to install.

[mon2]

ppbus_g3h 12.65V

Good. T2 is ok and your PPBUS_G3H was boosted using the SMBUS interface with the ISL9239/9240 controller.

A good investment (IMHO) is also a 100W PD capable power adapter (Anker, etc.) + 100W rated PD USB-C cable for 20V @ 5A support. It will be helpful here and in the future.

[Sergio Kub]

Very good, thank you very much for the tips.
I have already ordered a 100W PD charger (total 240W), according to the manufacturer.
Desktop GaN USB Type C PD Charger, Fast Charging, Mobile USB 3.0, 8 Ports, 240W - Aliexpress

[piernov]

Please stop buying cheap garbage power supplies from Aliexpress, I really doubt it's gonna provide proper 100W USB-PD (and certainly not 240W across all outputs) and you'll be sure to damage some devices at some point.

[Sergio Kub]

Okay, you're right.
I'll look for another one of more reliable quality.
Thanks

[Sergio Kub]

Hey
After the arrival of the PD 100W source, I tested the board again and it worked well... I had already repaired the board, changed a capacitor and was unable to turn it on because my power source was lower than the minimum required (96W), as reported by mon2 .
Thank you very much for the tip and support in repairing this complex logic board.
PS. The Desktop GaN USB Type C PD Charger is unreliable, but it powered the board without a battery.
Thanks to everyone who helped