This is the schematic diagram of pa-12 family laptop adapter. I think it is based on flyback topolgy but i have a problem understanding many things in it. Actually, in many circuits in general electronics i find many things like that and I can't figure out why these components are here? i understand the main concept of the circuit but the details are big mysteries for me. Anyways, I have pointed out to some of them in this circuit.
1- Are these resistors for filtering ? there are 2x1M ohm series resistors, why don't they just put one 2M ohm resistor?
2- The same, there are 2x750k ohm series resistors, why don't they just use one 1.5M ohm resistor? (Is that about standard values?)
3- What is that?
4- the same as question 1 and 2.
5- why don't they just use 1 equivalent capacitor ? .
6- What is that?
7- Is this a feedback network ? why don't they just use Ic ?
8- What is the purpose of this cap ?
9- What is the purpose of this resistor ?