Midea Power Control Board from Springer Air Filter

[vidarr]

The main board for my air filter broke. I know one resistor was bad and the capacitor next to it released its smoke. I replaced two capacitors and the resistor, but nothing changed, doesn't work.
This board is pretty simple compared to other things I tried to fix, so maybe this is a good time to learn how to troubleshoot component to component. I watched a few videos about this type board, but they fixed their boards by changing the same capacitors and resistor I did. Looks like that was the "common problem". I can't find anyone going further than that.
Can someone give me an idea about some kind of next step? I circled the replaced parts with new (in red).

Thanks!

[fzabkar]

I suspect that the LNK306P may have failed and sent the full rectified mains voltage to the load.

There is an application circuit in the datasheet (Fig 5, page 4):

https://www.es.co.th/Schemetic/PDF/LNK304-306.PDF

[vidarr]

Thanks for your input. I downloaded the data sheet and checked it out. Of course, it had to be the most complicated part.

First, do you think it fried everything after the IC in the circuit? I guess I can try to figure it out with a DMM, but if it is obvious, that would be great to know.

Also, on the data sheet, it has L1 an inductor, but on the circuit it looked like a resistor and had colored bands. I replaced it with a 2.2k resistor. Did I make a mistake?


data sheet:
Inductor L1
Choose any standard off-the-shelf inductor that meets the
design requirements. A “drum” or “dog bone” “I” core inductor
is recommended with a single ferrite element due to to its low
cost and very low audible noise properties.


Thank You!