Lenovo Yoga 3 (80jh) (Board shorted by me)

[barkinaksoy]

Hello,
Mainboard model: BTUU1 NM-A381 REV: 1.0
I had Picture issue and i was measuring the voltage and i made mainboard dead.


Marked area 1: I was measuring this are and i think i shorted this mosfet’s (marked with number 2) gate pin with 20 volt pin. After that stand by LED is gone. After that i unpluged the charger and pluged again. Still it was same and about 30 seconds later i saw smoke on IO chip. Voltage started to play 2- 6 volt and fan is spining. Later i saw smoke on u101 (marked with number 3)Also i can see damage on U8 (marked with number 4 ). When i measure the mosfet pins are shorted except gate pin. (marked with number 2). Now my question is what happend to the mainboard, is there way to comeback. If i will change these components will it work?
To not burn them again what should i check before.
Thank you for help.
Best regards.

[matic]

Hello!

Remove the burned KBC chip (UE1) and U101 from the board. After that perform the following measurements:
- Measure the resistance to ground on coils PL201 and PL202.
- Measure the resistance on the capacitors marked as "A" and "B" on the following picture.

[barkinaksoy]

Hello,
Thank you so much for the answer.
I removed them and i measured
pl202 1,9 kΩ and 1,9 kΩ
pl201 46,4 kΩ and 46,4 kΩ
A 0Ω and 1665 kΩ
B 0Ω and 99,4 kΩ

Best regards.

// posts merged

Also i removed U8 which burned.
And i measured again.
PL202 8,18 kΩ 8,18kΩ
PL201 45,9kΩ and 45.9 kΩ
A 0Ω and 1670 kΩ
B 0Ω and 101,4 kΩ
Best regards.

[matic]

Check all of the USB ports for bent/damaged pins.
If all seems ok, connect the power supply to the board and measure the voltage on capacitors marked as "A" and "B" on the picture in post #2.

[barkinaksoy]

So the resistance values are ok ? There is not damege on usb ports. Can i measure the voltages without the KBC chip and U101.
Best regards.

[matic]

So the resistance values are ok ?

Yes, the resistance values seems ok.

Can i measure the voltages without the KBC chip and U101.

Yes, you can. Remove the chip U8, if it is also damaged.

[barkinaksoy]

Thank you for answer.
I would like to ask that PQ108 when i measure its pins except gate pin the other pins are shorted eachother, is it normal?

// Posts merged

There are voltages 3.3v and 5.2v
Best regards.

[matic]

I would like to ask that PQ108 when i measure its pins except gate pin the other pins are shorted eachother, is it normal?

Yes, pins 1, 2, 3 are connected to each other and the same pins 5, 6, 7, 8.

There are voltages 3.3v and 5.2v

Ok, replace the KBC chip. It is important that you use the same KBC chip as the original (including extensions). The important markings are: IT8386E-192 - CXS

By the way, that KBC chip is programmed. Theoretically that KBC chip should programm itself with relevant data from the BIOS chip at first connecting power supply to the board. It will only work if the replacement KBC chip is brand new.

Please, follow the directions, which I described here before connecting power supply to the motherboard.

[barkinaksoy]

Today I replaced the KBC and PQ108, but when I plug the charger standby light comes on, after that keyboard lights comes on and both of them go off, but fan is spinning (hdd and fan pluged). I don't have voltages on CPU and Ram (PL801 1.5 volt and PL401 1.05 volt). If I don't plug the fan or hdd, standby light is shining and I have voltages on ram and CPU. CPU gets hot. (PL801 1.5 volt and PL401 1.05 volt). Where is the problem? Please help me.
Best Regards.
Barkin

[barkinaksoy]

Hello again,
Today i bought new io chip and i programed it like your description. I think it programed because during this 10 minutes blue light was shining about every half second. After that i turned back the changings on mainboard.
Without plug the Fan and HDD when i pluged the charger its otomaticly on i have screen (On hdmi because from the beginning there is issue with display.)
But; If fan is plugged when i plug the charger blue ligt turn on and turn off and fan is spinning fast. During this if i push the power button fan is spinning slowly normally and system is opening even i have screen. But if cpu gets cool and fan stopped still i have screen but if cpu gets warm and system wants to open fan again, system is going off. After that again i push the power button everything starting from beginning. Light is going off fan is spinning fast.
Push again power button. fan is spinning normally. System works.
When i push again power system is turned off.
Warming: if there is plugged hdd, everything more strange. With power button i never could make the system work.
Where can be the problem.
If it is too complicated, i can add a video.
Best regards.

[matic]

It seems like the KBC or BIOS chip is flashed with the wrong dump.
If you received a pre-programmed KBC chip it may be flashed with wrong dump.

I think you should use a KBC programmer and reflash the KBC + BIOS chip with the correct dump.
There is no way to reflash the KBC chip automatically again without the KBC programmer, because it works only on empty chips.

[barkinaksoy]

It seems like the KBC or BIOS chip is flashed with the wrong dump.
If you received a pre-programmed KBC chip it may be flashed with wrong dump.

I think you should use a KBC programmer and reflash the KBC + BIOS chip with the correct dump.
There is no way to reflash the KBC chip automatically again without the KBC programmer, because it works only on empty chips.

Firstly i used pre-programed one and there was also like that problem. And i would like to add that when i replaced it i saw some smoke around Q23 but i could not see exatly from where and i thougt i burned again The KBC (because i saw a soldering mistake on pins.) and i bought totally new one non- programed one and i programed it on board with your direction.
After that i have this problem. Is it for sure a problem about programing or may be short circuit? I dont have programmer and as i see it is expansive. I should bring the board to any repair shop.
Thank you for your answers.
Best Regards.

[matic]

Measure the voltages to ground on pins 2, 11, 12, 18, 21, 74, 107, 109, 111, 123, 128 of KBC chip.

Measure the voltages to ground on pins 86, 110 of KBC cip in the following cases:
a) Power button released.
b) Power button pressed.

[barkinaksoy]

I did not measure the voltages because i was confused that which step should i check and i scared to make short again someting and to burn it because is it too precision job to measure voltages on KBC chip i wanted to try firstly the program the chip. I went to computer serwis to program io chip. And they wanted from me 150 zl - 250 zl (40- 60 euro) to program the chip it is too expansive for me. Am i right? I did not want to program it for now. I will ask other serwises for price.
Today i put the board to laptop and even i have display !! . (If i dont plug the HDD, battery and fan of cpu.)
If i plug the fan of cpu. When i plug the power. Fan is spininning fastly (Led is gone) and i push power button computer opening good (Led everything fine).( BUT If fan is spininig, i mean if cpu gets cold and fan stop after cpu gets hot and fan wants to spin directly system is off)
Even i boot the system with usb drive. Keyboard, touchpad works fine.
In this case really i am confused.

[matic]

If so, the issue is not related to the KBC chip software.
You probably have a bad solder joint somewhere on the board. Use a magnifying glass or even better a microscope and inspect the solder joints on all pins of KBC chip.

[barkinaksoy]

Sir it is not soldering mistake for sure.
I check it with microscop too.
In the case even when it works if i plug the hdd, system is shut down and dont start again.
This computer killing me
I am adding this photo maybe you can observe something. Thanks for your interest.

[matic]

Does the battery charges, when the laptop is turned off?
Is HDD FFC cable and USATA connector on the motherboard in good condition?

[barkinaksoy]

Does the battery charges, when the laptop is turned off?

Yes there is charger led. But also when i plug the battery computer gets crazy but not as like HDD

Is HDD FFC cable and USATA connector on the motherboard in good condition?

Yes, totally they are in good condition.

[matic]

Anyway, I think it may be the KBC chip related issue.
Reflash the KBC chip with programmer (I can help you here, but the distance may be a problem).

[barkinaksoy]

I could definitely accept your help but distance is problem. I think i will try one more time pre-programmed KBC and if it will not help i can send you this board to check it sir. Thank you so much for your help. Best regards.