please help, friend, thinkpad L480 NM-B461 rev 1.0 JDOCK1 type C port 5volt only, thank you

[fredyjbi]

I have a thinkpad L480 NM-B461 rev 1.0 laptop functioning normally with Type 1 port (JUSBC1)
if you use port type C 2 (JDOCK1) with a usb type meter it only displays 5v, thank you
I tried to look at the schematic diagram USBC_VBUS20, which is the port path from JusBC 1 to U4701 then goes to the system2 charging IC, why is there no system2 path leading to the charging IC on the TYPEC_VBUS20 port which is JDOCK1, thank you for your help.

if you look at the power sequence there must be 2 types of port type C a (JUSBC1) via U4701 and port type C b (JDOCK1)
On the type B port I didn't find an IC that connects to the system2 charging IC
maybe MON2 can help me thank you

[fredyjbi]

Please help, this is a schematic, thank you
https://www.badcaps.net/forum/troubl...l580-el480-tvw

[mon2]

Hi. Still working on my beauty sleep. For now..

1) was this board worked on and parts are missing?

2) for power delivery, the CC1 and CC2 pins are used for the PD communication with a local PD controller.

Remove all power. No battery to the board. Meter in diode mode.

Red meter probe to ground.
Black meter probe to CC1 pin of the working port. Note the voltage.

Repeat for CC2 pin.

Now do the same for the non-working port.

Post each measurement.

It appears that port #1 is onboard but port #2 is through a dock?

[fredyjbi]

hi.. yes, we are in different time zones, I am in Asia, so when it is night here, it is daytime, sorry for the delay in giving me an answer

[fredyjbi]

Hi. Still working on my beauty sleep. For now..

1) was this board worked on and parts are missing?

2) for power delivery, the CC1 and CC2 pins are used for the PD communication with a local PD controller.

Remove all power. No battery to the board. Meter in diode mode.

Red meter probe to ground.
Black meter probe to CC1 pin of the working port. Note the voltage.

Repeat for CC2 pin.

Now do the same for the non-working port.

Post each measurement.

It appears that port #1 is onboard but port #2 is through a dock?

Before that, thank you for your interest in helping me, sir, here are the measurement results

emove all power. No battery
meter dioda mode
port JUSBC1 (port A)
USBC_CC1_CONN 0.618
USBC_CC2_CONN 0.618

port JDOCK1 (port B)
USBC_CC1_CONN 0.618
USBC_CC2_CONN 0.618

with adapters
port JUSBC1 (port A)
USBC_CC1_CONN 5v
USBC_CC2_CONN 1.6v

port JDOCK1 (port B)
USBC_CC1_CONN 0.618
USBC_CC2_CONN 0.618

USBC_CC1_CONN 0v
USBC_CC2_CONN 1.6v

[fredyjbi]

I have several of these matherboards with the same case type C port B with USB type c meter only shows 5v, while port A is fine the laptop can turn on normally

[mon2]

Confirm the following in read measurement.

port JDOCK1 (port B)
USBC_CC1_CONN 0.618
USBC_CC2_CONN 0.618

USBC_CC1_CONN 0v
USBC_CC2_CONN 1.6v

This line looks to be shorted and very likely linked to the ESD transient device on that line. First confirm if the measurement is the same and then can hunt for the offending part.

[fredyjbi]

Confirm the following in read measurement.




This line looks to be shorted and very likely linked to the ESD transient device on that line. First confirm if the measurement is the same and then can hunt for the offending part.

Can you please help me look at the shematic and find the problem, sir, thank you very much

[fredyjbi]

I have several of these boards sir with the same case

[fredyjbi]

Confirm the following in read measurement.




This line looks to be shorted and very likely linked to the ESD transient device on that line. First confirm if the measurement is the same and then can hunt for the offending part.

Sir, in this line D4404 has no components, thank you

[huzo]

Did anyone solve this? I have the simmilar problem... White light on the power button turns on, blinks and resets the board, like there is something pulling the voltage, but there are no shorts, maybe a shake with charger goes wrong? On battery also not working,Voltage drops from 11.9 to 11.3V on battery at power sequence...Charger gives 5V at L4706,4707 and then dissapears,lights go off and then 5V gets back again...but when i connect the phone charger, board turns on and light stays on, but no POST, all voltages present...drawing 900mA....but No VCC_CORE then...when on laptop charger, everything is the same,voltages come on , but only for a moment ,then blank, nothing, then again...like a boot loop...i measured this :port JUSBC1 (port A)
USBC_CC1_CONN 0.602
USBC_CC2_CONN 0.602

port JDOCK1 (port B)
USBC_CC1_CONN 0.602
USBC_CC2_CONN 0.602

with adapters
port JUSBC1 (port A)
USBC_CC1_CONN 0v
USBC_CC2_CONN 1.6v

port JDOCK1 (port B)
USBC_CC1_CONN 0.602
USBC_CC2_CONN 0.602

USBC_CC1_CONN 0v
USBC_CC2_CONN 1.6v


So i am missing 5V on USBC_CC1_CONN? But there is no short....charger and board are not communicating correctly?Should the voltage go from 5V to 20V?

[mon2]

Damage to the CCx pins is primarily from cross shorts of this low voltage line against Vbus (20v, etc.).

Are there ESD diodes on these shorted lines? If yes, remove them and test again. When inserting or removing these wimpy type C connectors, do so with the adapter power OFF. Once the connectors are mated securely, only then power the external power adapter.

If the PD controller + CCx communication is solid and working, then you should see 20V PD contract being negotiated.

Be sure to also inspect the USB Type C connector itself on the logic board. Perhaps some debris is on the contacts?

[huzo]

I charged the battery over night, and the battery is full, and when i press the power button i still get blinking power button and board reset...it's not a charging issue, something else is wrong...i tried a few bios dumps,still the smae, i will have to pull inductor by inductor and see where is the problem...

[mon2]

it's not a charging issue, something else is wrong

Correct. The PD controller remains at the power up default with the external Type C power adapter @ 5v. At 5v the supported is low as compared to the 20V PD contract which will often be at 5A = 100W power from the power adapter. Then the logic board stands a chance to be properly powered to boot. Yes, 5V may be acceptable to charge the battery overnight but at 20V, the logic board may be able to boot.

Do investigate each buck regulator onboard. Remove all power. Measure the resistance (not diode mode) of each inductor on the board. Checking for a lower than normal resistance on the rail which may indicate a shorted component is onboard. This shorted part will cause an excessive current draw and will force the rail to turn off.

[huzo]

All the inductors checked again, no shorts, all the voltages go on for a second...but what is interesting, when i plug in ordinary charger for an android phone, the board stays on, but there is no +VCC_CORE, but on original laptop chaarger or the battery all the voltages are present briefly and then the board resets...RSMRST signal also is on briefly....don't know what to look for next....

[mon2]

What are the specs of each power adapter?

USB C stuck @ 5v if using Android phone charger or is 20v? Current draw?

How current can the Android phone charger support? What is the peak current supported by the laptop charger?

[huzo]

Original charger is 20V, Android is 5V , and the board draws around 900mA when on android charger,i have a little usb thingy to measure current...i Can't measure the original charger current draw...but there is something else that is wrong ,because on the battery it also doesn't work, it acts just like on the original charger, Voltages start briefly and then go out and board again starts booting... i am just confused as what is happening...i Will give a BIOS dump for someone to try to repair, but i already tried a few dumps with cleared ME, it should at least act differently,but i doubt the BIOS is an issue...something else is wrong...But what , when i have all the voltages...

[mon2]

Remove all power. No battery. Meter in diode mode.

Measure each pin on the battery connector.

Red meter probe to ground. Black meter probe to the pin to test. Post each measurement.

[huzo]

But this is ok, battery charges and battery works, the board acts like on the charger...there are all voltages on the board , but briefly, for like 2-3 seconds ,and then the board resets...except when on the phone charger...then the board stays on, but there is no +VCC_CORE

[mon2]

Post #18.

The battery will charge if there is a leak in the power path from the external adapter. You can charge (albeit not recommended IMO - risky and can lock out your BMS) the battery pack with a dc power supply.

HP laptop battery charge with external power supply (youtube.com)

We are wanting to confirm that the SMBUS lines are ok which are necessary for the EC to communicate with the charger IC.

Check the full resistance path of each regulator rail on the board. If the resistance is not matching the schematic, the local regulator IC will deem the rail to be an excessive load and will power off the rail and laptop.