Lenovo L450 no display

[Jovica123]

Hello to everyone.
I have here lenovo l450
Motheboard is : AIVL1 NM-A351
Laptop has no picture and no backlight,but on VGA I have a picture.
First i checked if i have all voltages on lcd connector.
I have every voltage except +3vdmic,but i think this is for microphone ?
Please help me !
Display is ok,I tested it on another laptop.
Here are schematics i found,there is for be460 and nm-a351 : https://www.badcaps.net/forum/troubl...hlight=nm-a351

[randoomkiller]

Re: Lenovo L450 no display

Have you checked the fuses?
Or do you see any visible damage on the mb?

[mcplslg123]

Re: Lenovo L450 no display

Mb has dedicated graphics chip??

[Jovica123]

Re: Lenovo L450 no display

Have you checked the fuses?
Or do you see any visible damage on the mb?

Yes all fuses are ok,no visible damage on laptop.

Mb has dedicated graphics chip??

No


Thank you all for answers.
I checked all voltages on it8586e,all voltages are ok.
I tried to reprogramm bios chip,he has two of them q32 and q64.But it is same,no picture on display,on vga port is ok.
Is it maybe problem with EC dump ?

[beogeek]

Re: Lenovo L450 no display

Check if your Super I/O (EC) is generating the signal to enable the display. If the LVDS cable was removed while the MB had power it could have damaged the Super I/O.

I have a similar fault at the moment with the exact same symptoms and I've traced the fault back to the CPU... SO I will replace the socketed AMD A8-4500m and check as everything else is fine on the board, you may potentially have the same fault. I suggest you start at the EC and go from there. Do you have a board view file?

[Jovica123]

Re: Lenovo L450 no display

Here i'am again,after the fourth time ordering, the correct IT8586E finally arrived.
I programmed it with file from post below,and the picture come to VGA again.
But display stays black again,that means the EC was not faulty.
I don't have boardview file,that was a question from serb87.
Please help me
Greetings
https://www.badcaps.net/forum/showthread.php?p=1013079 file from post#1

[reformatt]

Re: Lenovo L450 no display

What is the part number for the display? Make sure it is indeed EDP and not LVDS.

This LCD is driven by signals from both the CPU and the PCH. The main ones to consider are PCH_EDP_PWM, which controls your backlight and BKOFF#. The former is a pulse width modulated signal, duty cycle will determine how bright your display is. If there is no activity on this line, your backlight will not work. BKOFF# comes from the EC, and I believe this should be low, but without the panel datasheet, I can't confirm.

The most common thing I've seen is damage to that PCH data line by inserting the display cable with battery connected.

[mon2]

Re: Lenovo L450 no display

According to the schematic, it is EDP style of LCD.

[Jovica123]

Re: Lenovo L450 no display

Yes it is.
Display Model No : B140HAN01.2
Sorry reformatt i didn't see your answer.
But even though i don't have backlight i should see something happening on the display when i light it up with a flashlight