Dear m1ch43lzm,

Thank you very much for your explanation, it does make a lot of sense to me.

I searched the hex chain you wrote in both my corrupted and new BIOS, and I do see what looks like a Win license key in both files, just after the hex chain. I do have slight differences around the license key, as shown on the pictures below. I am talking about the "I" which is ß in the new BIOS, but most importantly about the 3305156851758 which is 3305162513371 in the new one.

When transferring the license key to the new BIOS, should I also transfer that...

Dear all,

I did my first laptop repair related to a BIOS issue. Laptop is a Lenovo ThinkPad T480, and was not booting. With my brand new programmer, I did a back-up of the current not working BIOS, erased the BIOS chip, and flashed this dump: https://www.badcaps.net/forum/troubl...83#post3686683

Now the laptop works fine, I can access BIOS and boot on a USB drive. But I read stuff about DMI, and...

Hello,
Can you help me troubleshoot this laptop?

Model: Lenovo Thinkpad T480
Symptoms: When pressing the power button, powers on : power button is lit, the fan starts spinning, but it stops after a few seconds. Then the fan starts again, very fast. No picture. Same behavior with or without battery (which is charging fine by the way).
Current drawn:
- when plugged in and powered off, without battery : 45mA @ 19.9V
- when I press the power button, current jumps to 620mA, then goes up fast to 1.3A, and stays at 1.3A. Fan spins very fast.
Main power...

Dear all,

It's me again. This is an old topic but I still have the laptop.

I remembered I messed up something a few months ago while measuring voltages. I saw sparkles around a capacitor (but I don't remember which one). I then stopped to work on this laptop.

Today, I started to work on it again. When I plugged the USB-C charger, I now have 5V and around 300mA with no pattern.

I extracted the mother board, and I have no short on the main inductors. I plugged the board, and observed that there was heat in a zone with many components. I tested...

Dear mon2,

It is not the CPU / PCH under the heatsink. It is the U7 chip on the boardview. Reference of the chip is : C.S FH82HM370 B0 FCBGA874

It is the chip circled in red:



Regards,
mkdj...

Dear mon2,

Thank you for your comments. Before ordering anything, I tried something.

I have noticed that I had now 2 shorts on two different inductors: the 3.3V(which seems obvious as the regulator burned), but also on a 1.05V rail, which goes to the chipset nearby. Values of resistance were close to 0 Ohm at both inductors, and I did not have these shorts before.

Then I tried to remove the burned regulator. Doing so, as it and the board beneath it was burned, I ripped off some pads. I cleaned it. I checked again for short at the inductor of the 3.3V rail,...

Dear mon2,

Thank you for the explanation of the role of the multi-phase regulator. I believe I have found the 3V regulator. I have used the boardview and checked all the inductors. There is one that has a +3V_S5 signal, and that is connected to PU22. This chip is SY8286BRAC, and according to the datasheet, it is a stepdown DC/DC regulator : https://www.alldatasheet.com/datashe...GY/SY8286.html

I have checked the pins of this regulator. And I have noticed VIN is absent...

Back to square one : without battery, I have checked the voltage...

Dear mon2,

I can't find the actual regulator for the +3V rail on this board, which is why I am stuck. Also, there is no coin cell battery on this motherboard.

However, I have news. As the board when plugged in is taking 20mA, I tried to use my thermal camera to see if there was a chip heating. And I have found that something small is heating next to a PWM controller. Reference of the chip is MP2884AGU, and datasheet is here: https://www.alldatasheet.com/datashe...MP2884AGU.html

I don't know exactly what is heating (the chip itself or something...