Cooling fan not working

Hi all, I’m new here. And I would like to ask if someone is willing to help me with trouble shooting why the cooling fan in my Switch is not working.
Cleaned everything up. New cooling paste on the cpu. And replaced the fan with a new one because it’s an easy and cheap try. But no joy.
So I guess it’s not getting power. I’m pretty good with electronics (but not much experience with SMD and ‘modern’ stuff. More audio etc. But I can do this :wink:
The motherboard is HAC-CPU-10
If read about resistor or diode going bad. Can someone point out which components I should check. What it is and what it should be etc?

Wanted to add a few pics from Drive, but I am not allowed to insert links

Thanks in advance!

Check the diode that goes here if it is present, or check for a short between those points.

Thank you. There no diode there. Situation is like your photo. No diode.
I’ll check for a short between these points and will come back to you

Opened up the switch again and checked for a short between the poinst.
Measure 2.9k consistantly, so no short.

So, what’s my next step?

Good question… do the joycons charge / work correctly when in handheld mode?

Yes everything works perfectly except for the fan

Is there a schematic available? Then maybe there a way to trace the fan circuit and do some measurements (although everything is very tiny). I mean, the circuit must be triggered at some temperature point (sensor / cpu?) and somewhere along the wat either the power is lost or it’s shorted to ground. Right?

You can follow the traces using this: Switch erista board layers

Thank you. But that well be very hard to reverse engineer. I can’t figure it out that way.

But…it could be a bad fan after all…
Didn’t test the old nor the new fan before. Just replaced it.
But now I really wanted to know if the fan is okay. Need to eliminate things.
Turns out new fan is absolute garbage. Doesn’t totally nothing…
The old one (Switch had the same overheating issue) hesitates (willing to start but goes back and forth a couple of degrees) about 95% of the times. Got it spinnng a few times. (5v on the tiny contact cable).
So I guess the old one is just worn out and the new is not worth mentioning and I need to get me another cooling fan.
To be continued…

You can hook up 3v to the fan pins (after taking it out) and test if the fan even works stills.