I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

[luzvel64]

Apparently it does not receive voltage from the charger, this is type C.

I have injected 20v into the sensing resistor and the equipment does turn on and give video.

I have not been able to understand how the equipment that uses a type c charger works. I can't find boardview and I'm guiding myself with the schematic that I leave attached.

I hope someone can give me some help to find the problem.

Schematic - https://www.badcaps.net/forum/showthread.php?t=94842
.

[Sephir0th]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

In my opinion it is necessary to clarify that you have injected 20V into a power rail which is supposed to run with something around between 10Volts and 15Volts.

This was a really bad idea and you're lucky, if you haven't burned something irreparable already.

Does the charger supply 5V at VBUS right now or simply nothing?

[luzvel64]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

In my opinion it is necessary to clarify that you have injected 20V into a power rail which is supposed to run with something around between 10Volts and 15Volts.

This was a really bad idea and you're lucky, if you haven't burned something irreparable already.

thank you for answering. Does the charger supply 5V at VBUS right now or simply nothing?

The equipment works with 20v, which is why I injected that voltage, not to mention that I tried with lower voltages before and with 20 it turned on.

I can't find any voltage in the type c connector of the motherboard

[Sephir0th]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

It might be not clear that we have to differentiate between VBUS (VINT20_IN) and Main Power Rail voltage (VSYS15). For me it looks like you have injected into VSYS15, it could be also PR0201 (VINT20_IN). Either way, it wasn't clarified from your side yet.

But this is necessary now to conclude the situation of VBUS. Because if you can inject into VINT20_IN, or even better, even into one of the lines directly connected to the USB-C ports ( USBC_VBUS20 ) without issues (check resistance to GND there before), then you're not dealing with a simple short to GND but likely a issue with the USB-C Port(s) itself.

Not even at the CC lines any voltage? They're important for the communication between the charger and the PD-Controller.

[luzvel64]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

It might be not clear that we have to differentiate between VBUS (VINT20_IN) and Main Power Rail voltage (VSYS15). For me it looks like you have injected into VSYS15, it could be also PR0201 (VINT20_IN). Either way, it wasn't clarified from your side yet.

But this is necessary now to conclude the situation of VBUS. Because if you can inject into VINT20_IN, or even better, even into one of the lines directly connected to the USB-C ports ( USBC_VBUS20 ) without issues (check resistance to GND there before), then you're not dealing with a simple short to GND but likely a issue with the USB-C Port(s) itself.

Not even at the CC lines any voltage? They're important for the communication between the charger and the PD-Controller.

the voltage is injected into PR0201. The problem I have is that I don't receive any voltage in USB C, I have tried several chargers.

What would the CC lines be?

what is the PD-controller? in this case it is u6301?

[Sephir0th]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

Okay, so no short at VINT20_IN and charger is good.

U6301 is a simple port protector which will be triggered in case of a short of one of those CC lines which are described as CC1 and CC2 at JUSBC1. These lines are likely not the issue though, since you even don't have 5Volts at any VBUS pin of the same JUSBC1 as you shared here.

Take a look at the USBC_VBUS20 lines instead. Especially resistance to GND. There might be a failed load switch or simply a shorted capacitor. Something like that.

[luzvel64]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

Okay, so no short at VINT20_IN and charger is good.

U6301 is a simple port protector which will be triggered in case of a short of one of those CC lines which are described as CC1 and CC2 at JUSBC1. These lines are likely not the issue though, since you even don't have 5Volts at any VBUS pin of the same JUSBC1 as you shared here.

Take a look at the USBC_VBUS20 lines instead. Especially resistance to GND. There might be a failed load switch or simply a shorted capacitor. Something like that.

I have measured resistance.

black tip on gnd and red on USBC_VBUS20, mark 192.5.

and red tip on gnd and black tip on USBC_VBUS20 and it shows 54.9 ohms.

leave marked on a picture the point where you measured resistance

[Sephir0th]

Re: I need help with Lenovo E14 laptop. FE4A0/FE5A0 NM-C421 REV 1.0

As expected, your VBUS is (partial) shorted. U12501, U12502 and U12503 would be my main suspects here.