Chosen Solution
I have a Surface Pro 3 that had a cracked LCD. The screen worked, but the digitizer was broken and it wouldn’t accept touch input. I ordered a new LCD, but when I connected it, the backlight didn’t work. I could tell it was the backlight because you could see a faint image on the screen if you shined a light on it. I checked and re-seated all connections with no luck. I just chocked it up to a bad LCD and sent it back for a refund. I then ordered another LCD from an entirely different seller. It arrived today, but this one isn’t turning on at all. There’s no faint image on the screen or any indication that the LCD is even getting power. I plugged the tablet into an external monitor to rule out the motherboard, and it works fine on an external monitor. So my thinking is I either (a) have an incredibly bad string of luck with LCDs and this one’s dead too, or (b) there’s an issue with the LCD flex cable. I checked and re-seated the spacer between the flex cable and connector on the board and it looks fine. The flex cable itself looks okay to the naked eye, but it was bent back and forth a lot when I was trying to get the first LCD working. So I’m thinking perhaps it got crimped. I ordered a new flex cable to see if that fixes the issue. I’m just curious if there’s anything else I might be missing? Thanks! Update: The new flex cable arrived, but no luck. I also checked the fuses suggested by @jayeff below. Both are showing continuity with my Fluke DMM. Is there a possibility it could be the spacer/shim between the flex cable and motherboard? It doesn’t really seem like there’s anything in that shim that could break. I’m sort of at a loss.
Hi @jmg157 , If the problem is still there when you replace the video flex cable then did you disconnect the battery from the motherboard before replacing the screen? Sounds as though the backlight power fuse could be blown. With at lot of laptop displays (I don’t know if this is the case with yours) the power for the backlights is always being supplied to the panel and a signal is sent on the backlight enable lead to the panel to turn on/off the backlights. Usually the backlight fuse is mounted close to the video cable connector but again I don’t know if this is the case with your laptop but maybe still worth a check. Here’s an image from Step.7 of the ifixit Microsoft Surface Pro 3 Display Replacement guide where I’ve highlighted two components that may be worth looking at. If you have a DMM (digital multimeter) you could check them to see if one is a fuse by testing to see if they are short circuit and not open circuit or perhaps with the laptop turned on check if there is voltage on one side of the component and not the other indicating that it is blown. Again I don’t know the specs but with most it won’t be more than 20V DC
(click on image to enlarge for better viewing)
