Switch Lite No backlight, no shorts but low voltage

Nintendo Questions
1

Hi y’all.

I already saw a lot of topics here and there, but I could not figure out what’s going on with my Switch Lite.

Basically, there is no backlight, but I can see the screen if I shine a light to it.

I already replaced the ribbon connector and the daughter board itself.

All the buttons and stick work on daughter board.

Continuity is there and I checked my diode readings for the backlight connector:

  • starting rom top → 0.522 - 0.501 - 0.270 - 0 (well, the last pin is the ground)

Here’s pics of my Switch Lite:

postimg.cc (slash) fSsS15N8
postimg.cc (slash) Cn4n0DMS
postimg.cc (slash) cgw8D2VK

All seems to be there and nothing looks burned.

I checked for shorts around the inductor, diode and capacitors around the backlight IC on the main board, but I cannot read any short. Diode readings works in one way, as it should.

I just checked for voltage on the second pin of backlight connector and I get 3.4 volts and 3.1ish volts at the top terminal of the cap near the diode, at the top of the inductor.

I think the screen is NOT the culprit.

Backlight IC, diodes and capacitors/inductor do NOT get hot.

Inductor reads less than 1 ohm, so I think it’s good.

I get 3.3v at VIN pin for TPS61163… is this correct?

What do you advice me to check?

There is a method to check the backlight IC?

Can I check the backlight indipendently?

Thanks in advance.

2

Do you have access to another switch lite screen to try with this ones motherboard?
I have a regular switch that has no backlight, I can see the screen with a flashlight just like you, it ended up being the lcd it self, i put that board into another shell with a different screen and it works fine.

3

Hi. Thanks for your reply.
Unfortunately, I don’t have access to another unit.
It would have been a lot easier if I did, I know.
Anyway, I continued disassembly my Switch and I can clearly see stains from water damage on the back of back of the screen (the mirror-like part).
Since I don’t have any shorts and voltages seems to be there, and feedback pins are at same voltage of high voltage rail, I suggest that there is no power draw from backlight panel.
I know it could be a faulty Mosfet inside the backlight IC, but I think the fault it’s more due to the screen panel, than the IC itself.
I’ll proceed buying a replacement unit from AE.
I’ll trash 15 euros at most. Thanks

4

I solved my problem.
It was:

  1. burned out wide connector on daughter board
  2. burned out FPC cable, around bigger vias (gold turned gray)
  3. faulty backlight on LCD itself