Lenovo Thinkpad E15 - FE4A0/FE5A0 NM-C421 REV 1.0 USB C no charging

[camsmons]

Need help to fix my son's laptop.

I changed the USB C port, still no charging. checked U5901/RTS5455, pin 25 has 5V, pin 26 has 3.3V. Not sure where to check next.

If any one can tell where I should check next, it'll be much appreciated. Thanks.

[mon2]

https://www.badcaps.net/forum/troubl...-with-rts-5455

[camsmons]

https://www.badcaps.net/forum/troubl...-with-rts-5455

thanks for that. read that before. how do I know it's this RTS5455 has issue? I checked pin 26 which has 3.3V. does this mean it's good?

[mon2]

Pin 26 is only a fixed ldo rail at 3v3. It is a good start. This controller requires firmware to operate and communications will be over the CC1 and CC2 lines.

Do you have a usb type C meter? The linked thread mentions methods to reflash the firmware onto this device.

Be sure that CC1 and CC2 lines are ok. Meter in diode mode. Remove all power. Red meter probe to ground. Black probe to CC1 pin on the usb type C connector. What is the measurement?

Repeat for CC2 pin.

[camsmons]

I don't have a USB type C meter yet. Looking to buy one currently. I have this tester

Plugged in it to the USB C port. in diode mode, readings for CC1 and CC2 pin of this tester are all 0.599V.

Checked voltage of pin 9/CC1 and pin 11 /CC2 of RTS5455 when plugging power to USB C port, voltages are 0.004V and 1.661 V.

[camsmons]

the battery is flat currently. I'm considering to charge it separately, then power the laptop with the battery to flash the BIOS I downloaded from here, to see if it make any difference.

[camsmons]

tried to use official BIOS update, not allowed since AC power is not connected.

[mon2]

Checked voltage of pin 9/CC1 and pin 11 /CC2 of RTS5455 when plugging power to USB C port, voltages are 0.004V and 1.661 V.

The CCx voltage will only be active for the side being used by the power adapter for the power delivery communication. So for the low voltage side, flip the power adapter cable by 180 degrees and measure again to confirm this side is now active with the ~1v661 reading.

[camsmons]

The CCx voltage will only be active for the side being used by the power adapter for the power delivery communication. So for the low voltage side, flip the power adapter cable by 180 degrees and measure again to confirm this side is now active with the ~1v661 reading.

if flip the power adapter cable, CC1/CC2 voltages also flip from 0.004v/1.661v to 1.661v/0.004v.

The laptop works with the battery. could the issue be a mosfet for PD? Not sure how to check it.

[mon2]

Are you using the official power adapter?

Carefully measure the voltage to ground of each of the dcin mosfets. Need to confirm that the power delivery contract for 20v is being selected. After this stage, the mosfets must be enabled to charge the battery and to power the logic board.

If 20v is not selected then the power delivery controller is a suspect. Is the PD controller the original or it was replaced? The firmware in the PD controller can be reflashed by following the steps linked in the above post.

[camsmons]

Are you using the official power adapter?

Carefully measure the voltage to ground of each of the dcin mosfets. Need to confirm that the power delivery contract for 20v is being selected. After this stage, the mosfets must be enabled to charge the battery and to power the logic board.

If 20v is not selected then the power delivery controller is a suspect. Is the PD controller the original or it was replaced? The firmware in the PD controller can be reflashed by following the steps linked in the above post.

official power adapter has no issue, works for another laptop. also tried another official power adapter from another laptop, same result.

for sure 20v is not selected. there is only 5v from the usb c port.

the PD controller RTS5455 is the original one. at the beginning the charging issue should be only the usb C port which is damaged I believe, seems connectivity issue - had good or bad contact when the plug is pressed or bent. replaced the sub c port - did it twice due soldering skill😅.

now the connectivity seems all good. connections from all VBUS and CC1, CC2 pins of USB C port to board are all good. CC1/CC2 pins reached U6301 pin 4 and 5. it seems the power adapter is not communicated to lift up the voltage to 20v.

could you please help to tell which chip/pin to check next? Thanks.

[camsmons]

Re: Lenovo FE590 charging issue with RTS 5455



Yepp, charge the battery externaly, if you don't have appropriate external charger, use voltage and amperage as adviced on battery, ussualy in lenovo and asus batteries you activate BMS of battery by shorting plus and minus for milisec, and it starts to charge, done it myself doesn of times, works.

And for the Realtek IC, after you charge battery REFLASH a new BIOS to the motherboard, it should also reprogram the IC power controler.

without power adapter, laptop only runs on battery, how can I flash BIOS? downloaded bios update from official website, but couldn't flash it. it ask for AC power connection. anyone please help. thanks.

[camsmons]

had some progress. flashed the latest official BIOS, power adapter still remains at 5V, but can charge the battery slowly around 15W when the laptop is on. it shows the battery is charging, when the laptop is on, it used more power than what's charging. so battery level goes down slowly. only when the laptop is off, battery gets charged actually and slowly.

[mon2]

The PD controller must have valid firmware to negotiate with the USB Type C power adapter. If you wish to investigate further, consider a quality USB Type C meter that can offer a feature to display the power delivery (PD) contracts. Ideally a low cost PD bus analyzer is suited for this task but have seen some of the higher end PD meters on Aliexpress that claim to display the contracts. That is, when you mate the power adapter to the logic board with this meter in the middle - the meter will monitor the communication traffic over the CCx lines and offer details of which contracts are present inside of the power source (your power adapter) and then which contract was selected after the handshake. With 5 volts, this is the power up default so no contract is being selected. This may be due to corrupt firmware inside of this PD controller; the PD controller may be defective. A fresh PD controller will require for the firmware to be uploaded but from the earlier post by the other tech, this firmware is injected into the virgin PD controller IC via the bios upgrade. Perhaps wait till your battery is fully charged and attempt a reflash of the bios again with hopes that the PD controller firmware will be reflashed. Will search for the PD meter we saw on Aliexpress that looks promising. A lower cost USB PD meter will only offer the selected PD contract with the current draw and voltage being consumed by the logic board / target appliance.

[mon2]

Here are some meter options:

(cheap - claims to offer PD protocol monitoring and the video shows the table of PD contracts which is what is desirable. This will confirm that the PD controller is actually making the request with the PD power adapter source):

FNIRSI FNB38 Current And Voltage Meter USB Tester QC4+ PD3.0 2.0 PPS Fast Charging Protocol Capacity Test (aliexpress.com)

(perhaps the highest model from this company - maybe an overkill):

Usb Fast Charge Tester Trigger | Voltage Capacity Tester Usb - -fnb58 Usb Tester - Aliexpress

Suggest to seek out something like the above but from your local Amazon stores. Then you can return it if not required or does not live up to the claims.

[camsmons]

check D12501, reading starts from around 0.9v and stop around1.116v, reverse red and black prob, the reading is around 1.673v. does this mean this diode is bad?

[camsmons]

without power adapter, laptop only runs on battery, how can I flash BIOS? downloaded bios update from official website, but couldn't flash it. it ask for AC power connection. anyone please help. thanks.

found it, https://italchemy.wordpress.com/2021...thout-battery/

[mon2]

Good find! Keep posting your progress.

[camsmons]

For D12501, my understanding is at least one reading should be similar to the normal reading around 0.5v, as other diodes around. 2 readings both >1v sounds not right. Am I correct?

Just want to make sure before removing it to avoid making more troubles.

[camsmons]

I think I did a bad job when changing the USB-C port, several tiny components are missing from the board - those red circles. and one is misplaced - yellow circle. are they critical for PD?