@SerkanKaya For the working principles (I haven't wanted the youtube link you provided), you may wish to watch this video on 1950's switching supply. The author is quite thorough on explaining the concept and details. He will be repairing a
vibrator that used to be used in automobile radios (I used to repair them as a kid) and Ham radio equipment used in cars and trucks. The key here is that Carlson goes through the schematic with great care. So you should be able to follow the idea, I think. How it may apply here? Not sure, but it may help.