Looking to learn about troubleshooting my Lenovo L14 Gen 1

[Lifeisfun]

I did check for shorts on the regulator chips and did not find any so I soldered it back ( also ordered replacements but my experience with ICs from China is bad)
Will test it and see if it works, I didn't want to cause damage with the EC chip removed.
The info about editing the laptop details I got from the pre-programmed chip seller on eBay (very reputable item # 297257916579)

After fitting this chip you will need to fill in the missing data from the bios setup
like the Serial Number, Board Number, This is done using a usb drive at bootup
you need to download (Lenovo Maintenance Diskette) See picture No2.
The Type and Serial Number can be found on the sticker on the back cover on your laptop.

I'll see how it goes.

Thanks again!

[m1ch43lzm]

I suggest sending a message to the seller to confirm if you need to add that info after replacing EC, as i don't know the specific details about your motherboard, as most laptops store that info on the BIOS
If needed, they may be able to add that info while programming the EC

Laptop should power on after replacing EC in any case

[Lifeisfun]

I suggest sending a message to the seller to confirm if you need to add that info after replacing EC, as i don't know the specific details about your motherboard, as most laptops store that info on the BIOS
If needed, they may be able to add that info while programming the EC

Laptop should power on after replacing EC in any case

Will do!
Thank you!

the 3.3V regulator is working fine

[Lifeisfun]

To my absolute surprise it's partially alive! 😅
It will make funny tone melody when powered on, charge the battery but nothing else.
I do not have DDR4 stick handy, is this the reason why it wouldn't boot or show anything on the display?

Thanks!

[Sephir0th]

Without a EC the board can not boot up. This is impossible. You need to wait until you can replace it.

[Lifeisfun]

Without a EC the board can not boot up. This is impossible. You need to wait until you can replace it.

Yes, that was already done, it wouldn't charge or respond to the power button either.

[m1ch43lzm]

To my absolute surprise it's partially alive! 😅
It will make funny tone melody when powered on, charge the battery but nothing else.
I do not have DDR4 stick handy, is this the reason why it wouldn't boot or show anything on the display?

Thanks!

It won't work without RAM, as that board doesn't have onboard memory
Schematics and board view only show 1 RAM slot and no onboard RAM, please install memory (that may be the meaning of the "funny tone" you heard)

[Lifeisfun]

It won't work without RAM, as that board doesn't have onboard memory
Schematics and board view only show 1 RAM slot and no onboard RAM, please install memory (that may be the meaning of the "funny tone" you heard)

Will do! Thanks for the confirmation, you are great help!

[Sephir0th]

Yes, that was already done, it wouldn't charge or respond to the power button either.

Oh, you are right. Missed that it was already done.

Well, then it could be still a underlying problem, which more or less means that we have to start over with the diagnostics to fins the next problem. I would begin with a close look at pictures of how the EC was soldered...

Of course only when inserting the RAM doesn't change anything

[Lifeisfun]

Got the DDR4 memory but sadly still no picture, it will consume 40mA before I press the power button, then it will settle on 500mA, CPU is warm and if I leave it on for long time the fan will kick in.
If I hold the power button it will reboot after 10 s or so, if I do that two times in the row it will turn off and not reboot.
What I noticed is I get no VCCGFXCORE_I voltage on the PL1003 coil, is this normal?
Any ideas welcomed.

[m1ch43lzm]

https://www.badcaps.net/forum/troubl...rpose-of-vccgt
From post #2

I am missing VCCAXG/VCCGFX/VCCGT (iGPU core voltage), how do I solve it?

The iGPU core voltage is almost never relevant. It typically only comes up when there's a significant load on the iGPU. It can often be seen spiking a couple of times on the oscilloscope when POSTing.

In other words, it's generally normal that it's missing. If you have some kind of issue with the machine, the cause is most likely elsewhere.

Does the laptop react to caps lock key? Same with a basic, cheap USB wired mouse, it should light up the sensor (don't use a gaming mouse with RGB lights, it will mislead you)
If the caps lock LED turns on/off as you press it, then the issue is "No display"
Otherwise, is "No POST/no boot"

Do you still get the beep codes? If yes, you can check with "Lenovo PC Diagnostics" app for your phone

You can also build this simple USB port tester, the red LED blinks if there's activity (system is alive)

The resistors are 100 ohms (i saw several versions of the same circuit, with resistors from 100 ohms to 1k, whatever works), the red LED is connected to D+ through a 100 ohm resistor

Also wait for Sephir0th reply

[Lifeisfun]

https://www.badcaps.net/forum/troubl...rpose-of-vccgt
From post #2

Does the laptop react to caps lock key? Same with a basic, cheap USB wired mouse, it should light up the sensor (don't use a gaming mouse with RGB lights, it will mislead you)
If the caps lock LED turns on/off as you press it, then the issue is "No display"
Otherwise, is "No POST/no boot"

Do you still get the beep codes? If yes, you can check with "Lenovo PC Diagnostics" app for your phone

...

Very interesting, I thought that could be my problem.
No longer get any beeps out of it even with the memory removed again (this is the memory I got DDR4 16GB 3200MHz (PC4-25600) CL22 SODIMM)
No light or response from the caps lock key
Yes USB mouse will light up and blink couple times when booting, after that the LED is steady on.

Not sure where to look further
No change when I plug in the battery only difference is that the battery charging circuit coil gets hot and the input power consumption is close to 3A.

Thanks again for your time!

[Lifeisfun]

Oh, you are right. Missed that it was already done.

Well, then it could be still a underlying problem, which more or less means that we have to start over with the diagnostics to fins the next problem. I would begin with a close look at pictures of how the EC was soldered...

Of course only when inserting the RAM doesn't change anything

I know it doesn't look pretty but I checked every single pin and they are all soldered.

[Lifeisfun]

Here is link to video of the power meter when it powers up
https://photos.app.goo.gl/uN8PJgtKXa3UPpKE8

[Lifeisfun]

Just some additional info on what I tested so far:
I did check the EC chip soldering pin by pin and they are all connected
I checked all coils and looks like all voltages are present except the VCCGFXCORE_I voltage I asked above.
Since there is no response from the keyboard I checked for power on the connector and there is 3.3V present.

When I power it on (without battery and cmos batt connected)
The power button (on its own) blinks 2 times then it turns on, fan turns on for couple seconds and turns off again.
It takes 20V and power meter shows after while about 450mA
It will sit like this long time without any change (nothing is hot, only some components warm to touch like the CPU and some coils)
If I press the power button nothing happens
IHold it it will blink twice again and reboot to the same state. (no change from above)
When I attempt to reboot it for the 2nd time holding the power button it will turn OFF and the power meter shows consumption about 42mA
After this the power button no longer responds. (also tried keyboard but nothing)
To reboot again I have to unplug the USB-C and plug it in again.
Mouse connected to USB port blinks couple times and after the amperage settles down it stays lit.

Any ideas would be welcomed!
Thank you!


Sephir0th
m1ch43lzm

[m1ch43lzm]

Get the ThinkPad E14, R14, E15, S3 Gen 2 Hardware Maintenance Manual (HMM) from here:

https://support.lenovo.com/us/en/sol...-e15-20rd-20re

From page 46

LCD Self Test
When you turn on the computer and the LCD goes black, run LCD Self Test to help you determine whether the LCD functions normally.
To run LCD Self Test:
1. Ensure that the computer is connected to ac power. Then, press the power button for about seven seconds to turn off the computer.
2. Press Fn, left Ctrl, and the power button at the same time. If the computer displays five solid colors in sequence across the entire screen, it indicates that the LCD functions normally.
3. The test lasts for about 20 seconds and then exits automatically. You also can press the power button to exit the test.

If you get beep codes (speakers plugged in of course), check page 44, download the Lenovo PC diagnostics app on your phone (link in hardware maintenance manual is broken, search app store/play store) to decode beep codes

[Lifeisfun]

Get the ThinkPad E14, R14, E15, S3 Gen 2 Hardware Maintenance Manual (HMM) from here:

https://support.lenovo.com/us/en/sol...-e15-20rd-20re

From page 46


If you get beep codes (speakers plugged in of course), check page 44, download the Lenovo PC diagnostics app on your phone (link in hardware maintenance manual is broken, search app store/play store) to decode beep codes

Thank you, will do that.
Unfortunately it no longer makes any sounds. It did only the first time I powered on without memory, but now even when the stick is removed no beeps.

[Lifeisfun]

Another question, any reason for the BQ chip to be 49C when the battery is not even connected? The mosfets around tested OK and not shorted.
When I connect the battery (12.6V charged to 11.35V) the charging voltage is only 12.4V not 15V and it's slowly dropping not going up.
Could this be possible reason for the board not to post?

Thanks

[mon2]

49C

That is toasty. Chip was replaced? Was the chip soldered in the proper orientation on the board?

[m1ch43lzm]

It's NVDC design (Narrow VDC), see https://www.badcaps.net/forum/troubl...arging-circuit
I agree with mon2, the BQ25700A is too hot, it's available at mouser if its determined to be faulty

So the main power rail and battery charge voltage is dependant on the battery configuration, so for 3S battery the fully charged voltage should be from 12.6v - 13v, similar as the Macbook charge circuit with the ISL chips
With battery unplugged you should get 12.6 or 13v
Could be the main rail (VSYS15) is unstable?, that may be the cause