Switch Lite - help identify IC

[Phantomas77]

Hi all!

I've a Switch Lite that does not have any signs of water damage and doesn't power on. I don't have the possibility to perform voltage injection so I was messing around replacing the known "problematic" IC's.

This Switch was drawing 15V/0.1A before and after M92T36 replacement and started to draw 0.6A after BQ24193 replacement. I'm not sure if the BQ chip is legit since I got it from Ali, but today I analysed the PCB under a thermal camera and got a heat signature coming from BQ and another IC labeled as "U81 O".

I've ordered some BQ chips from Digikey that should arrive soon, but before replacing it I was wondering what that "U81" might be. Does anyone know what's the function of that IC and the specs?

Thanks!

 

[The Real Jdbye]

You have a thermal camera but not a bench power supply?
You can get bench power supplies pretty cheap.

 

[thesjaakspoiler]

On the iFixit site it looks like the marking is U83 :
https://www.ifixit.com/Teardown/Nintendo+Switch+Lite+Teardown/126223
https://guide-images.cdn.ifixit.com/igi/mOpEXbmlDop6Hrt6.full

AliExpress says it's some sort of LCD driver chip
https://www.aliexpress.com/item/1005001718249024.html

It's close to the LCD connector so that would make sense.

 

[Phantomas77]

Thanks for pointing me out in the right direction @thesjaakspoiler , it seems to be the backlight IC, since it's located nearby the flex ribbon that is connecting the left joycon board and power/volume flex and has LCD backlight connector on it. Already found one on Ali.

I can't see any screen image under light and the BQ heating is a bit worrying, so probably something else is going on in the circuitry that I need to investigate. Though in the meantime I'll order that backlight chip.

 

[jkyoho]

if you drawing 15v 0.6A and BQ goes 50 something degree, that's normal. and Yes ,the "U81" is backlight ic, you could use/search for TPS61163A