Lenovo yoga 900-13isk2 Backlight Fuse?

[mgrharry]

Working on a Lenovo Yoga 900-13isk2. Screen initially had some glitches that could be resolved by pushing on bottom corner of screen, possibly from a loose cable but the screen is glued together so it's very difficult to remove the LCD assembly without cracking the glass. Opted to just install a new display assembly. When installing it the battery was of course disconnected, and yet with the new screen I get no backlight or visible image of any kind. Same with the original screen now. I can hook it up to an external monitor and verify that it is booting properly and interestingly I can tell that the touchscreen functionality is working by looking at the response on the external monitor but Windows device manager does not detect the display at all.

So I'm thinking that perhaps the backlight fuse is blown.

I will post some photos below. Can anyone help me in locating the fuse? Or any alternate suggestions about what might be causing this would be helpful. Thanks.


Close up of display connector

[piernov]

Re: Lenovo yoga 900-13isk2 Backlight Fuse?

If there is no image on the screen (you should be able to see it faintly when approaching a flashlight on a clean screen), this is not a backlight issue. Even more so if the screen isn't recognized.
Are you sure the cable is OK? For the screen to be detected it needs to receive 3V and the I2C communication datalines must be working (SDA and SCL) for the GPU to read the EDID ROM. Also ground must be properly connected.

[mgrharry]

Re: Lenovo yoga 900-13isk2 Backlight Fuse?

I double checked and there is no visible image at all, nor is the built in display detected in device manager. So I suspect it is more than a backlight issue. A side note-- touchscreen function still works (it all comes through the same ribbon) so it is getting at least partial power. Hmm, where to go from here?

[petehall347]

Re: Lenovo yoga 900-13isk2 Backlight Fuse?

replace the cable

[piernov]

Re: Lenovo yoga 900-13isk2 Backlight Fuse?

Touchscreen is probably on the USB bus, so it will have its own power and data lines, and its own connector inside the display assembly.
Display not being detected is most likely a cable/connector issue. Reseat it on motherboard's and LCD panel's end, try with another LCD panel and try replacing the cable.

[mgrharry]

Re: Lenovo yoga 900-13isk2 Backlight Fuse?

Unfortunately the display assembly is glued together so it's not possible to reseat the display ribbon at the back of the LCD. But I do have two screens-- the original one and a new one, and the same problem is there on both so unless both ribbon are defective it has to be something with the motherboard itself.