The led that shows that pattern (i.e. 3 blinks) is the LED_PWR and it's controlled by the EC (page 85 of the schematic).
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From post # 7 - you have ~20v onboard. If the power adapter is the USB Type C, this confirms that the TE is working since the power delivery contracts have been negotiated with the external USB C power adapter and the power rail has switched from the power on default of 5v to 20v. Can you confirm this detail? The communication is over the CCx pins. There is CC1 on one side of the USB C connector; CC2 pin will be on the other side of the USB C connector.
Turn off all power and unplug the USB C power adapter from the wall - personally do not trust them at all - then rotate the USB C plug to your laptop by 180 degrees. Now plug the power adapter to the AC socket. Do you see ~20v again? If yes, the PD controllers are working.Comment
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Yes, I can confirm that the PD negotiation seems to work properly. I tried with the USB-C connector in both positions (and disconnected the AC adapter from the wall as you suggested each time).
In both cases, on the board I can measure 19.8v on pin 45 (VREGIN20) of the TE.
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To me, TE is working fine due to this 20v negotiation.
Carefully, measure the voltage to ground on each pin of the DCin mosfet that follows this power path to power the main power rail.
Test the voltage to ground on mosfet @ PQ0201.
Interested in:
source (1-2-3) ; select any pin.
gate (4)
drain (5-6-7-8) ; select any pin.
Post each measurement.Comment
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On my board, the PQ0201 is a Dual N-channel MOSFET:
Here are the measurements:
pin measure pin measure 1 ~400mV 5 0v 2 20v 6 0v 3 20v 7 0v 4 20v 8 5.8v 9 ~308mV Comment
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Mhhhh... while I was looking at page 102 for the measurements, I noticed that the -EXTPWR signal is originated there, and it's actually low!
Based on the power sequence from the X270 documentation, -EXTPWR should be the next in line to go up (in the other schematic it's called -EXT_PWR_GATE, but I guess both refer to the same signal)Comment
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My bad...indeed a dual mosfet inside a single package.
However, in the schematic there are 2 part numbers used for this component. Each is a DUAL N-channel mosfet so this implies that the gate voltage must be higher than the voltage being passed betwee source / drain pins to enable.
On the BQ series, the N-channel driver pin should be ~25v and is based on adapter voltage + REGN voltage = 20v + 6v = ~25v to enable the mosfet.
Noting that we do not have this voltage from the BQ charger IC, proceed to test the following pins of interest.
Remove all power. Meter in resistance mode.
Measure the resistance across each mosfet pin:
source / drain
source / gate
gate / drain
of the 1st mosfet inside this package
then repeat for the 2nd mosfet inside this package.
We are checking if there is a low resistance which often means the mosfet is shorted and needs to be replaced. Each measurement should be hundreds of k ohms or higher if normal.
Assuming the resistance checks are ok, carefully review the voltage to ground of the following pins of interest on the charger IC:
VBUS ; pin # 1
REGN ; pin # 28
ACN ; pin # 2
ACP ; pin # 3
See attached for the datasheets for the dual mosfet parts used at this location by the PCBA shop:
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The Dual MOSFET on the board is marked 0924NDI, so it's the Infineon.
High side (gate:1 -- source:9 -- drain: 2,3,4)source / drain 150k and raising source / gate 220k gate / drain 450k and raising
Low side (gate: 8 -- source: 5,6,7 -- drain: 9)source / drain 87k source / gate 210k gate / drain 346k
On the IC charger I find:pin name measure 1 VBUS 20.12v 2 ACN 20.11v 3 ACP 20.12v 28 REGN 6v Comment
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The low side mosfet inside this dual mosfet looks to be quite low (87k ohms) for a good mosfet.
Suggest to flux and remove this dual mosfet and test the component while it is on your workbench. Are these measurements still this low on your bench? Each should be hundreds of k ohms or higher. This part may be defective.
Can you measure in the same manner the dual mosfet @ PQ0202? Post your measurements.
Your voltage measurements look good.Comment
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Here what the PQ0201 shows when off the board:
High side (gate:1 -- source:9 -- drain: 2,3,4)Low side (gate: 8 -- source: 5,6,7 -- drain: 9)source / drain 4M source / gate OL gate / drain OL source / drain 123k source / gate OL gate / drain OL
And the PQ0202 (in circuit):
High side (gate:1 -- source:9 -- drain: 2,3,4)Low side (gate: 8 -- source: 5,6,7 -- drain: 9)source / drain 160k and raising source / gate 219k gate / drain 229k source / drain 141k source / gate 201k gate / drain 340k Comment
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Both PQ0201 & PQ0202 look too low for me. Suggest to flux and replace both dual mosfets. Before you do this, measure the fresh ones while they are on your work table. You can use the measurements as a comparison of a known good mosfet. Each will be much higher in measurement. Recommendation is to source from tier 1 distributors like Digikey / Mouser / Arrow and only if you must, Aliexpress but select a vendor with very high ratings.Comment
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Many thanks for the suggestion. I'll give it a try.
As a matter of fact, I have another board from the same Lenovo generation but based on AMD Ryzen architecture. This part of the board is based on the same BQ charger IC. I'm tempted to take the dual mosfets from there
What do you think?
I'd replace the Infineon 0924NDI with SM7360EKQG (more beefy), and the SiZ340DT with AONH36334 (a bit smaller in amps). The latter code is from the schematic, the package is actually marked "M6 VUA 2W0E08" on the board, but I couldn't find a datasheet using this identified. I'm attaching the datasheets for reference.Comment
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I finally found some time and replaced the dual mosfets.
I replaced both PQ0201 and PQ0202 with their counterparts from a similar board I have (let's call it blue-pcb). The latter has other problems, but the power stage seems fine since it comes up, charges the battery and shows BIOS screen.
Unfortunately, I still get the 3 blinks on the power button white led. So no visible change in behavior.
The blue-pcb donor board keeps working the same way with the mosfets from the board I'm trying to repair.
Any other idea?Comment
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Recently, I had the same problem, and it was resolved by flashing the EC controller and selecting the correct BIOS.
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Forgot about this thread. Are you still working on it? Do you get VSYS15 at all or is the main power rail dead? Have you checked it isn't shorted?Comment
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Hi there! Thanks for sharing. Honestly, I also considered trying thatOriginally posted by UADmytro View Post Provided that I'll be able to find a bin to flash for this board, is it something I could do with a ch341a?
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