Lenovo ThinkPad T490 power delivery

[rumpumpel1]

I have a Lenovo ThinkPad T490 that will not start. When the charger is plugged in, the power indicator flashes 3 times, the charging LED lights up, the fan starts spinning, but the charger remains at 5V, which is not the fault of the charger.
The 5V appear on the main power rail at the current sensing resistor.
What can I check next? How can I check the power delivery protocol?

Schematics and boardview can be found here: https://www.badcaps.net/forum/showthread.php?p=1146770

[Sephir0th]

Re: Lenovo ThinkPad T490 power delivery

Sounds like a communication issue with the CC lines between USB-C Port and PD-Controller. Is it the same with both USB-C Ports?

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

yes, the laptop shows the same reaction on both ports.

[Sephir0th]

Re: Lenovo ThinkPad T490 power delivery

Take a look at U6201 and U6301.

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

on the USB-C jack I have 5V at VBUS and 1,6V at USBC_CC1_CONN.
The 1,6V are propagated through U6301 until the PD Controller.
So the connection is ok.

PD controller generates LOD_3V3 (measured only 3,0V).

[Sephir0th]

Re: Lenovo ThinkPad T490 power delivery

Check resistance to GND of LDO_3V3 for sanity

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

resistance to ground for LDO_3V3 is 50 kOhm.

[mon2]

Re: Lenovo ThinkPad T490 power delivery

USB-C is a reversible connector. Turn off all power.

Rotate the USB-C connector by 180 degrees and dock it to your laptop. Then plug in the adapter to your mains (110/220 VAC) socket.

Any difference?

Also, consider to test the CCx lines by removing all power. Meter in DIODE mode.

Red meter probe, yes red to ground.
Black meter probe to CCx pin on the connector. What is the reading?

Repeat for the next CCx pin on the same connector.

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

there is no difference when rotating the connector after unplugging the charger for a while.

In diode mode with red to ground the meter reads for both CC lines 0,64V.
With black to ground there is no reading.

[mon2]

Re: Lenovo ThinkPad T490 power delivery

The CCx lines appear to be ok.

You really require a USB-C meter that can display the power delivery contracts or a USB-C bus analyzer. Each can monitor the data flow, if present from the PD controller on the logic board and the power adapter. After this handshake is completed, the controller will select the best suited power contract to power the logic board. This is often a stand alone pd controller with an onboard cortex M0 or similar microcontroller.

Any physical damage to the pd controller? Post a pic of the device.

The 5 volt on vbus is a power on default value.

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

there is no damage.

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

here is the output of a KINGST LA5016:

Time[s],Item,Data,Remark
0.6433412200,Preamble
0.6435501700,SOP,,
0.6436155200,Header,0x55A1,DataObject:5 Source V3 DFP Source_Capabilities
0.6436809800,PayLoad[0],0x0A01912C,V:5V Imax:3A
0.6438115200,PayLoad[1],0x0002D12C,V:9V Imax:3A
0.6439423300,PayLoad[2],0x0003C12C,V:12V Imax:3A
0.6440729100,PayLoad[3],0x0004B12C,V:15V Imax:3A
0.6442037100,PayLoad[4],0x00064145,V:20V Imax:3.25A
0.6443343900,CRC32,0x866F5D98
0.6444650800,EOP,
0.6445364400,Preamble
0.6447502300,SOP,,
0.6448170800,Header,0x0401,DataObject:0 Sink UFP GoodCRC
0.6448839400,CRC32,0x5FAFE7A7
0.6450176900,EOP,
0.6491990600,Preamble
0.6494128500,SOP,,
0.6494797100,Header,0x1082,DataObject:1 Sink V3 UFP Request
0.6495466100,PayLoad[0],0x1000280A,PD0#1 I:100mA Imax:100mA
0.6496804800,CRC32,0xC60E64AA
0.6498141800,EOP,


and here are the same data from a working T480s:

0.4871178600,Preamble
0.4873268300,SOP,,
0.4873921800,Header,0x53A1,DataObject:5 Source V3 DFP Source_Capabilities
0.4874576600,PayLoad[0],0x0A01912C,V:5V Imax:3A
0.4875882200,PayLoad[1],0x0002D12C,V:9V Imax:3A
0.4877190000,PayLoad[2],0x0003C12C,V:12V Imax:3A
0.4878495900,PayLoad[3],0x0004B12C,V:15V Imax:3A
0.4879803800,PayLoad[4],0x00064145,V:20V Imax:3.25A
0.4881111000,CRC32,0x7052585E
0.4882418300,EOP,
0.4883129300,Preamble
0.4885256900,SOP,,
0.4885922300,Header,0x0241,DataObject:0 Sink UFP GoodCRC
0.4886587600,CRC32,0x46B50D97
0.4887920000,EOP,
0.4929590300,Preamble
0.4931717900,SOP,,
0.4932383200,Header,0x1082,DataObject:1 Sink V3 UFP Request
0.4933048800,PayLoad[0],0x53051545,PD0#5 I:3.25A Imax:3.25A
0.4934380800,CRC32,0xBB68BE6D
0.4935709800,EOP,

so normally the laptop is requesting PD0#5 I:3.25A Imax:3.25A
and this T490 is requesting PD0#1 I:100mA Imax:100mA.

Why?

[TuanTongbadcaps]

Re: Lenovo ThinkPad T490 power delivery

I have a Lenovo ThinkPad T490 that will not start. When the charger is plugged in, the power indicator flashes 3 times, the charging LED lights up, the fan starts spinning, but the charger remains at 5V, which is not the fault of the charger.
The 5V appear on the main power rail at the current sensing resistor.
What can I check next? How can I check the power delivery protocol?

Schematics and boardview can be found here: https://www.badcaps.net/forum/showthread.php?p=1146770

Have you checked the firmware of the U5502(TBT ROM), and the voltage at VCC3_LDO_TBT_SPI?

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

Bingo! that's it!

I downloaded the newest TBT firmware from the Lenovo website and after flashing the new firmware the voltage showed 20V!

Thanks a lot!

[mon2]

Re: Lenovo ThinkPad T490 power delivery

Can you post the details on how you reflashed the firmware? It will help future readers.

Good job!

[rumpumpel1]

Re: Lenovo ThinkPad T490 power delivery

There is nothing special about flashing the TBT firmware. I did it the same way I would flash any BIOS.
As I said, I got the firmware from an update package on the Lenovo website. When installing the package I used the 'extract only' option. There was only one bin file, which I padded with 0 up to 1024kB (which is the size of the flash memory).