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mrfree2ita replied to Lenovo T14 gen1 no power, 9v on power rail instead on 15v

in Troubleshooting Laptops, Tablets, and Mobile Devices

05-22-2025, 11:59 PM
Kinda I made some progress, I think I fixed the power issue, but at the end the laptop was not working (probably an issue linked to a bad EC-BIOS combo).

You can find details of my troubleshooting adventure on this post [url]https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/3465716-thinkpad-t14s-gen-1-nm-c891-no-power-i-could-use-some-help-with-the-troubleshooting[/url]https://Kinda :) I made some progres...bably an issue...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

04-21-2025, 11:22 AM
Hi there! Thanks for sharing. Honestly, I also considered trying that 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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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

02-21-2025, 07:53 AM
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?

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-09-2024, 05:01 PM
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....

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-09-2024, 12:15 PM
Here what the PQ0201 shows when off the board:

[B]High side[/B] (gate:1 -- source:9 -- drain: 2,3,4) [TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD]source / drain[/TD]
[TD]4M[/TD]
[/TR]
[TR]
[TD]source / gate[/TD]
[TD]OL[/TD]
[/TR]
[TR]
[TD]gate / drain[/TD]
[TD]OL[/TD]
[/TR]
[/TABLE]

[B]Low side[/B] (gate: 8 -- source: 5,6,7 -- drain: 9) [TABLE="class: text_table, border: 1, cellpadding: 5, width: 500"]
...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 04:14 PM
The Dual MOSFET on the board is marked 0924NDI, so it's the Infineon.

[B]High side[/B] (gate:1 -- source:9 -- drain: 2,3,4) [TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD]source / drain[/TD]
[TD]150k and raising[/TD]
[/TR]
[TR]
[TD]source / gate[/TD]
[TD]220k[/TD]
[/TR]
[TR]
[TD]gate / drain[/TD]
[TD]450k and raising[/TD]
[/TR]
[/TABLE]

[B]Low side[/B] (gate: 8 -- source: 5,6,7 -- drain: 9) [TABLE="border:...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 12:09 PM
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)

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 11:54 AM
On my board, the PQ0201 is a Dual N-channel MOSFET:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"Screenshot from 2024-12-07 18-40-17.png","data-attachmentid":3523472}[/ATTACH]

Here are the measurements:
[TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD]pin[/TD]
[TD]measure[/TD]
[TD] [/TD]
[TD]pin[/TD]
[TD]measure[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]~400mV[/TD]...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 11:04 AM
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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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 07:31 AM
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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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-07-2024, 07:16 AM
I couldn't find any information about this for the ThinkEngine-3. According to the schematics, it can be one of the following: [TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD]Vendor[/TD]
[TD]P/N[/TD]
[TD]LCFC P/N[/TD]
[/TR]
[TR]
[TD]ROHM[/TD]
[TD]BD4179MWV[/TD]
[TD]SA000090J00[/TD]
[/TR]
[TR]
[TD]TOSHIBA[/TD]
[TD]TC62D518FTG[/TD]
[TD]SA00008E500[/TD]
[/TR]
[/TABLE]
Based on my understanding, on this board the EC role...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-06-2024, 11:49 AM
Some additional pieces of information... The power button led blinks only on the moment I plug-in the AC charger.

On AC plugged-in (both with or without battery), the following power rails are showing stable and correct voltage:
VCC5M_PD
VCC3M
VCC5M
VCC1R05_SUS
VCC3_SUS

while:
VCC1R2AP stays at 0v
RSMRST is also low

so it seems to me that accordingly to the power up sequence you suggested before it's kind of stuck on (or just before) the A_ON signal.

Moreover, on battery only (i.e. AC unplugged), when...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-02-2024, 02:03 PM
[B]"It's alive!" [/B]

I know that it has been a while, but I finally replaced the ThinkEngine chip and the board shows some signs of life!

The power led comes on (orange), and the [U]white led[/U] under the power button [U]blinks 3 times[/U] (then it stays off). My USB-C power meter shows that the board takes 30mA for a few seconds, then goes back to 0mA and keeps cycling between the two values.

Any idea what the 3 blinks might indicate? What would be the next logic step in the troubleshooting?[B]"It's alive!" [/B]

I know

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-28-2024, 10:31 AM
Both resistors' values are spot on when not in circuit.

Out of curiosity, I also tried injecting 12.8v (300 mA max) on pin 44 of the ThinkEngine, but I didn't notice any change (i.e. M_ON didn't go high). Moreover, my PSU didn't report any current draw.

Many thanks again for your interest and support. I'll see if I can find the chip from a reputable source since I don't have a donor board at the moment.

Do you know if a new ThinkEngine (BD4179MWV) would need to be programmed?

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-26-2024, 12:33 PM
Well, that's interesting.

R9505 and R9509 are both 0ohm resistors and I get consistent values while checking them.

R9504 and R9506 are... funky

Every time I measure them after a try (i.e. I plug in the charger and measure voltage on pin 44) I get different values:

For R9504 (nominal 1Mohm 1%) I've observed values like 780k, 804k, 921k and around 970k in different tries.
For R9506 (nominal 1.82Mohm 1%) I often get something around 1M, but I've also seen 1.6Mohm and even 1.7Mohm once.
C9505 is there and since it's in parallel with...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-25-2024, 12:30 PM
Thanks for your input reformatt, very interesting points.

Here the measurements on the UTE1A (starting top-left corner in the schematic and moving anticlockwise). In the table, I use [B]mV[/B] when I measured just a few millivolts:
[TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD][B]PIN[/B][/TD]
[TD][B]Measure[/B][/TD]
[TD][B]Label[/B][/TD]
[TD] [/TD]
[TD][B]PIN[/B][/TD]
[TD][B]Measure[/B][/TD]
[TD][B]Label[/B][/TD]
[TD] [/TD]
[TD][B]PIN[/B][/TD]
...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-24-2024, 11:11 AM
I didn't manage to find much about the ThinkEngine chip (marked BD4179MWV (on my board) or TC62D518FTG).

Do the values I shared look good/healthy to you?

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mrfree2ita started a topic Lenovo Thinkpad T14s gen1 NM-C791, PD controller flash memory U15 request

in BIOS Requests ONLY!

09-24-2024, 06:27 AM
Lenovo Thinkpad T14s gen1 NM-C791, PD controller flash memory U15 request

Does anyone have a dump of the PD controller flash memory U15 from a working board of this kind?

Many thanks in advance.

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-22-2024, 03:58 AM
Here the measurements on the UTE1B (starting top-left corner in the schematic and moving anticlockwise). In the table, I use [B]mV[/B] when I measured just millivolts: [TABLE="border: 1, cellpadding: 5, width: 500"]
[TR]
[TD][B]PIN[/B][/TD]
[TD][B]Measure[/B][/TD]
[TD][B]Label[/B][/TD]
[TD] [/TD]
[TD][B]PIN[/B][/TD]
[TD][B]Measure[/B][/TD]
[TD][B]Label[/B][/TD]
[TD] [/TD]
[TD][B]PIN[/B][/TD]
[TD][B]Measure[/B][/TD]
[TD][B]Label[/B][/TD]
[TD] [/TD]
...

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mrfree2ita replied to ThinkPad T14s Gen 1 (NM-C891) no power, I could use some help with the troubleshooting

in Troubleshooting Laptops, Tablets, and Mobile Devices

09-21-2024, 12:26 PM
Thanks for pointing this out. Indeed, the VCC3M rail is absent at the moment. PU0501 is one of those that wait for the enable signal M_ON from the ThinkEngine. In fact, if I inject 3v on the M_ON line the VCC3M rail comes up regularly.

Resistance to ground on the inductor PL0501 starts around 900kohm when I start measuring and then it goes down until it stabilizes at 40kohm...

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Lenovo Thinkpad T14s gen1 NM-C791, PD controller flash memory U15 request

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