Lenovo Yoga2 13- No display and light only on keyboard

[lorins_core]

i need request for bios clean for this.

problem: No display and light only on keyboard

Lenovo Yoga 2 13
Mobo: LA-A921P
5B20G19198

Thank's

[Attif]

Re: Lenovo Yoga2 13- No display and light only on keyboard

keyboard on light but screen have no display ???
1.u check the screen cable first clean and fix again.
2. check the voltage on screen coming or not 3.3v and 19v

[kjchatman]

Re: Lenovo Yoga2 13- No display and light only on keyboard

i have this same board and it doesn't stay on. i hit the power button and the keyboard lights and the fan beings to spin. after three seconds it will shut off. sometimes it will cycle and do the same thing twice or three times. i've also noticed that if i plug in an optical mouse that the red light is on even though i haven't cut the machine on yet. the cpu will stay warm even the machine isn't cut on

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

i have this same board and it doesn't stay on. i hit the power button and the keyboard lights and the fan beings to spin. after three seconds it will shut off. sometimes it will cycle and do the same thing twice or three times. i've also noticed that if i plug in an optical mouse that the red light is on even though i haven't cut the machine on yet. the cpu will stay warm even the machine isn't cut on

It's 5 seconds LED on and I have a board with the same issue. If somebody has an idea what to to.. I would me more than happy.

I checked 19v, 3.3v, 1,35v, 5v... all on.. CPU 1.68v is also coming up.

It's consuming 0.06 till 0.010 Amps in IDLE. And while power on (till power off in 3-5 seconds) 0.280 amps.

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

i checked all power raills. all are up and running. also replaced the bios (also chip) and tested 3 versions from different sources.

I also soldered an LED on the bios on PIN 4 and 5... to visualize communication but it's only blinking once and than it's done... on an X1 there where several blinking.

+3VS
+3VALW
+1.5VS
+1.05VS_VTT
+CPU_CORE
+0.675VS

are present and get shutdown after a 5 seconds.

seems like the bios won't get read.

If i delete the bios or remove the chip it's NOT powering off. it stays at 0.260 amps.

[SMDFlea]

Re: Lenovo Yoga2 13- No display and light only on keyboard

Try this bios and EC ,extracted from lenovo bios, dmi added. Check how hot the KBC gets during boot up if this bios doesn`t work .

MOD EDIT: bios moved - https://www.badcaps.net/forum/showthread.php?t=100248

.

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

Many thanks... Unfortunatly I don't have an EC Programmer (yet?)

Tried the Bios alone, no change.
I guess we both guess it has to do with the EC Flash/Programm.
No heart at all at the EC. Tested with thin layer of alkohol.

(Would you recommend the: Vertyanov programmer?)

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

ne heat (not heart)

[SMDFlea]

Re: Lenovo Yoga2 13- No display and light only on keyboard

ne heat (not heart)

Have you tested with the LVDS connected .

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

display was connected.

[SMDFlea]

Re: Lenovo Yoga2 13- No display and light only on keyboard

Test R127,R128,RP4,RP6 and R108 if they`re on the board.

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

What did you mean with dmi added with your bios? Isn't dmi in any bios by default?

RP4 (15 ohm)
RP6 (0) [i gues it's the one next to SPI flash, there is a red dot on the number, so I can't really read it, but makes sense while looking into schematic)
R108 (15)

Unfortunatly I can't locate R127 R128. Don't know where AF1, Y6 are to find.

Maybe you can show me where both resistors are located by this (random) picture https://e.allegroimg.com/original/0c...268e238ddc630e

[SMDFlea]

Re: Lenovo Yoga2 13- No display and light only on keyboard

"What did you mean with dmi added with your bios? Isn't dmi in any bios by default?"

Your serial number,UUID,MAC address are in your bios backup,its the DMI info.The bios from lenovo doesn`t include it,its copied over during the bios update.Because your flashing the bios with a programmer you need to add the dmi info,manually with a hex editor or with dmi tools, either from lenovo or whoever made the board,compal,bitland .

There`s no boardview available so finding r127,r128 is going to be.. very difficult. I don`t know what else to suggest .

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

I ordered the ec programmer... I will put the board aside for a while.. maybe reprogramming the ec will help.

Can you guide/give link how you edited the provided bios? extracting / adding the dmi part and maybe other interessting stuff that would be usefull to know?!

thanks for your help anyway.

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

btw. I think I was wrong about 1.35v rail. Sorry for the faulty hint.
I'm pretty sure it's shorted.

unfortunatly the ram is soldered.
I made a picture with the powerline

There are 2 bridges (underneath they look the same) I removed them and than the short on the power supply side is gone (green).

I attached 1.35v and 3A to the grounded side (marked in blue) it draws 0.6v with 3A. I also tried with 5A (think it was 1v) but nothing really gets warm. Something should get warm but I can't feel it by hand or by evaporating alcohol. 5w should be enough to get something warm, but I couldn't find anything warm, so maybe it's really a RAM chip which can dissipate the heat too good?!

And of course more than the 4 caps in the red rectangle are shorted. They are just examples.

Any recommendations?

[mcplslg123]

Re: Lenovo Yoga2 13- No display and light only on keyboard

I dont think they are shorted as depicted in your pic-since ram is onboard they are showing short.

[Pferd5]

Re: Lenovo Yoga2 13- No display and light only on keyboard

I messured the ressitance on the caps again and they are 0 Ohm. I also messured on a T440s (4GB onboard) and one some caps I get something about 100 Ohms. As far As I understand the repair logices (so far) there is a short on 1.35v. I'm more than open to test any recommendations what to do next.

[ravi_1617]

Re: Lenovo Yoga2 13- No display and light only on keyboard

It's 5 seconds LED on and I have a board with the same issue. If somebody has an idea what to to.. I would me more than happy.

I checked 19v, 3.3v, 1,35v, 5v... all on.. CPU 1.68v is also coming up.

It's consuming 0.06 till 0.010 Amps in IDLE. And while power on (till power off in 3-5 seconds) 0.280 amps.

Hi
its same problem ,few times ON & OFF repeat ,than stays OFF.
sometimes stays ON, CPU heats up and fan don't starts cpu heats up more and more, So i force turn OFF.
any solutions
Thanks

[ravi_1617]

Re: Lenovo Yoga2 13- No display and light only on keyboard

When laptop came USB 3 was broken pins were short.

[Sametbey]

Re: Lenovo Yoga2 13- No display and light only on keyboard

I think there is a caps failure in the 1.35v line. If ram chips had short circuits, they would have been warmed up. It should be very troublesome to control ram chips by removing them one by one. It should also find a guide to cancel ram chips.