Lenovo T14 MainBoard NM-C931 no image

[dggn]

Laptop as in the subject. No image and no voltage on the PL1002 coil. According to the schematic it is the value of VCCGFXCORE_I. CMOS battery removed. Maybe someone had a similar problem and direct what to check ?

Current consumption 722mA board on, 22mA board off. And below the voltage and resistance values of all coils

PL0401 5.31V
PL0201 9.30V
PL0501 3.3V
PL301 5.1V
PL1201 1.2V
PL1301 1V
PL1002 0V
PL0902 0.8V
PL0904 0.8V
PL0903 9.2V
PL0909 0.8V
PL1102 1V
PL1502 0.8V
PL1501 0.8V
PL1601 1.3V
L5602 0.9V

PL0401 86kΩ
PL0201 0,6MΩ
PL0501 5,2kΩ
PL301 114kΩ
PL1201 151kΩ
PL1301 54Ω
PL1002 6,7Ω
PL0902 4,3Ω
PL0904 4,1Ω
PL0903 16MΩ
PL0909 5,3Ω
PL1102 16,9Ω
PL1502 5,6Ω
PL1501 4,8Ω
PL1601 604Ω
L5602 0,95kΩ

[SMDFlea]

Link to schematic & boardview -> https://www.badcaps.net/forum/troubl...31#post1768898

[mcplslg123]

Try disabling onboard ram

[dggn]

I tried to disable using this thread

https://www.badcaps.net/forum/troubl...1-thinkpad-t14

And also edited the bios using this thread

https://www.badcaps.net/forum/troubl...-scripts/page2

but nothing helped

[Sephir0th]

CapsLock test?

[mcplslg123]

There is no proven bios claiming to disable onboard ram for this model in this forum and ram disable thru that script posted by smdflea dont work in majority of the cases.

So i'm not confident whether ram is disabled correctly or not. Unfortunately, i dont have any solution either for this model.

[n_pac]

CapsLock test?

I was looking at your video for about this kind of Lenovo T14 gen 1 and that PD controller video is very helpful. Thank you mate! I also have a USB Type C power jack problem, one of the VBUS pins is detached from the board and the questions are:

1- Since there are 4 VBUS pins connected together, would be any problem if one of the VBUS is missing?
2- The resistor R6304 it is not giving any ohm value and I think the current it's not flowing through it! Probably damaged from any short circuit..! Could this be the problem that I am not having 20V in the test point TP6301 or at USBC_VBUS20 test point? (part of schematic image attached)

3- What is the CapsLock test and how to perform it?

Thank you in advance
Danke schon!

[Sephir0th]

If one single pin is missing, it most likely isn't a issue for a board which doesn't consume a lot of current. R3604 is supposed to measure 1 MegaOhms. If the multimeter isn't auto-ranging, it has to be set manually to the 200K or 2M range to measure properly.
however, there should be at least 5 Volts to measure at USBC_VBUS20_CONN, otherwise you are dealing with another problem here. Like a short to GND on this track, or maybe the other three pins not attached to the board too anymore? What's the history here?