Lenovo Thinkpad L560 No backlight

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

You mean where leads the pin 26 on the screen cable end?

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

You should have a circuit on the screen that indicates the screen is closed. You need to figure out what this circuit is.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

Well that's weird.
I removed the camera, the voltage still 0v
Then i removed the screen, voltage still 0v
No switch appears anywhere but when i remove the cable from mb the 3.3v appears.
How is that possible?

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

Because you have a circuit that detects if the screen is closed. Nothing to do with the screen itself or the camera. It should be a Hall effect sensor.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

I agree but on the cable there is only the screen and camera connector, nothing else to connect to a lid switch.
I always wonder how the mb detects the lid is closed in modern laptops.

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

On the schematic you have the connector "CAM/MIC/LID" Module pin define, pin 2 is the LID SWITCH, either with this connection you can find what is connected, or follow pin 26 on the connector of the screen. You will see what is connected for the switch.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

Wait.
In JEDP1 the 1 2 and 3 pins are the same and all 20v.
In what connector the pin 2 is LID switch?

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

On the schematic page 19 you have the "Module pin define", I don't know if it's a separate connector, but you have 10 pins defined from 1 to 10. If you can't find what it is, just follow pin 26 to see what is connected to it.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

The pin 26 from screen connector ends in both ends:
At camera flex, pin2 & 3 & 4 & 9 and connector chassis.
At screen LVDS connector at several pins plus on connector chassis too.
What a mess

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

I guess the sensor is on the camera pcb because it's completely aligned with the magnet on the palmrest.

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

Can you take a picture of the camera circuit board, that might be enough to identify the chip.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

Unfortunately the chip is covered behind shielding that is soldered on the pcb.

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

So, with all the tests you've done, pin 26 stayed at zero volts when disconnecting the connector from the camera and when disconnecting the screen from the ribbon. The only time you have 3.3 volts on pin 26 is when you disconnect the display ribbon from the motherboard with nothing connected to it.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

So, with all the tests you've done, pin 26 stayed at zero volts when disconnecting the connector from the camera and when disconnecting the screen from the ribbon. The only time you have 3.3 volts on pin 26 is when you disconnect the display ribbon from the motherboard with nothing connected to it.

Exacty, this is what i was about to write you!
And that,'s the strangest case i ever seen, since the cable is just a cable.
No pcb, no switch, no other circuit just cable.

[JaroTech]

Re: Lenovo Thinkpad L560 No backlight

The display cable is defective, pin 26 is shorting another pin and its voltage is zero volts. The motherboard thinks the lid is closed and sets the BKOFF# signal to zero, no backlight. All this to conclude what mon2 said: "Tested with a good fresh and known lcd cable?".

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

Well that make sense now, i'll order a cable from ebay and i'll come back with news.

[Andreasbest]

Re: Lenovo Thinkpad L560 No backlight

New cable arrived and screen worked, success
Now that laptops works and installed Windows i noticed another issue, i get a repeated warning that one unknown USB device has exceed the hubs power limit but on Device Manager there is no device with exclamation mark or enable/disable.
How can i found out which particular device is this?

[Suzn123]

hello
i have similar problem , on same mb L560 ver.2

here are my test results , dont know which side is faulty

external monitor display : OK
lcd screen : OK (checked with another working led screen)
cable : OK i guess ( checked every pin for shorts)
cam module : no short to ground
lenovo LED for LOGO : OK

also here are the voltage test , with and without cable+monitor connected

.
plz help me where is the problem and which section i shoud check .
thanks

[mcplslg123]

Very likely a faulty cable as LCDVDD is pulled down to zero.

[Suzn123]

Very likely a faulty cable as LCDVDD is pulled down to zero.

about LCDVDD , when nothing is connected its 3.36v , even with only cable still 3.36v. . .. but when connected to lcd first it fluctuate, come and go . . and dissapear . . .. . i didnt find the cable so i checked the cable for shorts and the cable is fiine . .and lcd display is also fine cause i have 2 lcd to check with . . . . . . . . .. . .. . then i put jumper on U9 ic for LCDVDD , 3.36v is constant with { EPD_HPD being 2.7v on one lcd and 3v on another lcd }.. . still no display on any lcd . . . . .. . . . .. .

is it because of bios? but has display on external vga? .. . . the original bios is lost so i put random working bios with different mac address on it . ... .. . .. .

or is PCH faulty? . ..

i just dont wanna give up untill i know whats the problem . .. .

help me kind people , ,.. . .. . . . ..

can somebody make me bios for L560 ver.2 with mac address 9829A67C9C7D. . ... . . i used cleanme bios which shows another mac 9829A67FD68D on external display.

. .