Laptop Keyboard problem and it is not the keyboad!!!

[ladharimohamed2]

Good night everyone,
My problem seems to be strange and i didn't found anything on the internet so here it is if someone have faced it and could help.
It is a Lenovo Legion Y520-15IKBN that have some keys on the keyboard not functioning ( E , G , H , 8 , 9 , FN , ....) so i thought that it is a keyboard problem, i ordered a new one and replaced it , at first night it worked perfectly the second night those keys were not functioning but when i press one of them 5 or 6 times they function again i restarted the laptop sometimes works sometimes not sometimes i press several times so they work again. after that they stopped completely. The exact same keys that were not functioning on the old keyboard became non functional on the new one so i guessed that it is not a keyboard problem.
The trucks on the motherboard are connected from the keyboard connector to the super IO that i checked and are OK , the connector is ok too , i updated the bios , reinstalled the driver and didn't fix the problem.
Does anyone have any idea about this issue ?
Thanks.

[mcplslg123]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Very likley a defective keyboard as long as connection from kbd connector to SIO is intact.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Very likley a defective keyboard as long as connection from kbd connector to SIO is intact.

but it is a new one, and the defective keys are the exact same ones on the old keyboard
I'm thinking it is a SIO problem maybe ?

[myth77]

Re: Laptop Keyboard problem and it is not the keyboad!!!

check keyboard connector on motherboard with microscope...maybe one pin from inside is bent or dirty or similar.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

check keyboard connector on motherboard with microscope...maybe one pin from inside is bent or dirty or similar.

all good

[myth77]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Second i would check in continuity mode connection from those pins to ite chip. And if all ok then i would check pins on ite chip if one of them is making bad/loose connection to the motherboard (solder crack).

[Vesko356]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Second i would check in continuity mode connection from those pins to ite chip. And if all ok then i would check pins on ite chip if one of them is making bad/loose connection to the motherboard (solder crack).

... The tracks on the motherboard are connected from the keyboard connector to the super IO that i checked and are OK , the connector is ok too , ...

.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Second i would check in continuity mode connection from those pins to ite chip. And if all ok then i would check pins on ite chip if one of them is making bad/loose connection to the motherboard (solder crack).

I mesured every pin of the connector and are perfectly connected to the SIO, i even resoldered the SIO to the motherboard for perfect connection.

the pins of the keyboard are from 36 to 46 and from 51 to 65.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Hi,
I disassembled the old keyboard and found that all keys that are not working have the same exact line on the keyboard. That line is connected to pin number 10 of the keyboard connector wich is connected to pin number 60 of the SIO. i even mesured connection directly from those buttons to their pin of the SIP (60) and they are connected. So i guess there is nothing left but a SIO problem.

[mon2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Remove all power. Meter in diode mode. Keep the keyboard connected to the logic board.

Red meter probe, yes RED to ground.

Ground meter probe to the pin to test.

Test each pin from #1..#24 on the keyboard connector.

Post each measurement and the pin number being tested.

Update - check the SIO pin that is common to the non-working group in DIODE mode and compare this value against a working group.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Remove all power. Meter in diode mode. Keep the keyboard connected to the logic board.

Red meter probe, yes RED to ground.

Ground meter probe to the pin to test.

Test each pin from #1..#24 on the keyboard connector.

Post each measurement and the pin number being tested.

Update - check the SIO pin that is common to the non-working group in DIODE mode and compare this value against a working group.

Hi mon2,
these are the measurements :
Pin 1 : 601 | Pin 2 : 601 | Pin 3 : 703 | Pin 4 : 701 | Pin 5 : 603 | Pin 6 : 704 | Pin 7 : 703 | Pin 8 : 601 | Pin 9 : 703 | Pin 10 : 700 | Pin 11 : 601 | Pin 12 : 600 | Pin 13 : 699 | Pin 14 : 602 | Pin 15 : 599 | Pin 16 : 599 | Pin 17 : 599 | Pin 18 : 600 | Pin 19 : 599 | Pin 20 : 600 | Pin 21 : 597 | Pin 22 : 599 | Pin 23 : 601 | Pin 24 : 601 |
I also measured pin number 60 of the SIO that is common to the non-working group and found 700 value. Pin 64 of the SIO wich is a working group found 700 value too.

[mcplslg123]

Re: Laptop Keyboard problem and it is not the keyboad!!!

I'm still batting for the "NEW" keyboard being also defective. All chinese stuff and they are known for their "QUALITY". So take it with a pinch of salt. have faced a new keyboard found defective on many occassions.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

I'm still batting for the "NEW" keyboard being also defective. All chinese stuff and they are known for their "QUALITY". So take it with a pinch of salt. have faced a new keyboard found defective on many occassions.

Hi mcplslg123,
After further investigation i found that is a well known fault on this laptop with the exact same buttons.
https://forums.lenovo.com/t5/Gaming-...3631381?page=1

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Hi mon2,
these are the measurements :
Pin 1 : 601 | Pin 2 : 601 | Pin 3 : 703 | Pin 4 : 701 | Pin 5 : 603 | Pin 6 : 704 | Pin 7 : 703 | Pin 8 : 601 | Pin 9 : 703 | Pin 10 : 700 | Pin 11 : 601 | Pin 12 : 600 | Pin 13 : 699 | Pin 14 : 602 | Pin 15 : 599 | Pin 16 : 599 | Pin 17 : 599 | Pin 18 : 600 | Pin 19 : 599 | Pin 20 : 600 | Pin 21 : 597 | Pin 22 : 599 | Pin 23 : 601 | Pin 24 : 601 |
I also measured pin number 60 of the SIO that is common to the non-working group and found 700 value. Pin 64 of the SIO wich is a working group found 700 value too.

Hi mon2,
after more measurements i found different values of pin number 60 of the SIO (the pin wich the line of the non functioning buttons are connected)
the value on point 1 = 567 (point 1 where the pin 60 of SIO is soldered to the motherboard).
the value on point 2 = 700 (a track of that pin)
PS : continuity between those two points is 0 and no visual problems of connection between the two points there. What can it be ?
thanks a lot

[mon2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

The diode readings should be the same at the start of the pad and to the end of the trace that mates with the pin.

In posted pic, concerned about the lack of fiberglass view between the pins. Can clearly see a solder ball between 2 pins of this region.

Suggest to apply flux onto the pads and then use desolder braid to draw up the excess solder between the pads. Then use IPA alcohol to clean up the area.

In summary, solder sould be present on the pin and landing pcb pads. The area between the pins should be clean and without solder else there is a risk of a short.

[reformatt]

Re: Laptop Keyboard problem and it is not the keyboad!!!

I have seen a similar issue on a HP. IIRC, when I scoped each pin, the pullup on one (which is internal to the EC itself) was low when that column of keys was activated. So the EC itself was the fault.

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

Hi mcplslg123,
After further investigation i found that is a well known fault on this laptop with the exact same buttons.
https://forums.lenovo.com/t5/Gaming-...3631381?page=1

Well, it is a company fault that no one found an effective solution , even those who have returned their laptops to lenovo service center and made a repair the fault appeared again after like one month or two.Lenovo support marks the problem as solved and talks to customers with arrogance with no informations about the origin of the problem, they only said that is a hardware issue.
Thanks everyone for helping.

[mon2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

More good reading:

https://www.ifixit.com/Answers/View/...in%20downwards).

[ladharimohamed2]

Re: Laptop Keyboard problem and it is not the keyboad!!!

I ordered a second new keyboard and works fine for now, maybe when those SIO legs where partially shorted they caused the first new keyboard to fail. I also took out the ram cover completely because it is near the keyboard connector and may affect the connector or its tracks going to SIO and finally i protected this second new keyboard ribbon cable with adhesive tape.
This second new keyboard works fine for now and hopefully it continue to do so.