Switch Lite black screen and speakers buzzing

My nephew has a switch lite with a black screen and buzzing from the speakers. Sometimes the screen displays vignettes. The water damage sticker is still unchanged (however to me seems like water damage).

Things I’ve tested so far

  • tested daughter board with a known working motherboard and my nephews switch screen and touch screen work fine.

Where should I start testing the board? I have a multimeter, hot air station and soldering iron

It’s probably either the backlight IC (or support circuitry) or the backlight ribbon (or the connector for it) possibly trace damage too. I’d have a search on My Mate Vince youtube channel for his Switch lite videos as I think he’s encountered this problem a couple of times and his videos are very long which is great if your a beginner :slight_smile:

This ones a little odd, if it was purely a backlight issue then you wouldn’t see vignettes (though an image of this for clarification would be good) :thinking: maybe it’s the LCD connector or maybe just the LCD itself is bad. Have you tried the board in another known good assembly to see if the problem carries across?

If you want you can post some images of the backlight IC and connector areas etc and also of the BL ribbon contact sides facing up. if you want us to take a look, just upload them to imgur and format the link like

imgur (dot) com/yourimages

Here’s a video of the display and the buzzing noise for reference. I’ll give that video you mentioned a watch and see if it will help me diagnosis where the issue is.

imgur dot com/a/aZLfxeF

Ahh so I didn’t realise the LCD / picture was working as a whole, so in this case it’s probably not going to be backlight related. I think you have LCD issues or possibly LCD connector issues so I’d start there, I’d inspect the LCD connector and ribbon for signs of damage if good then If you have a known good LCD or assembly to transfer the board too, I’d verify that first.

I’ve put a known working motherboard into this teal one and the display and digitizer seem to be working properly. Going to clean the connectors and inspect to see if there’s any issues there. Not sure about the buzzing audio though

Looking at the lcd connector under magnification looks like one pin is bent snd 1 pin is missing. Going to replace this connector and see if that fixes the display issue.

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