Electronics > Repair
Know the pinout and trace IC offline flyback code
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salviador:
That's an LM358 that should act as a current control, that resistor is actually "cooked", but with the multimeter I have 100 ohms hoping that that is the value.
IC flyback is on the right side where I removed it

Harry_22:
Yes I see. How did you understand that the controller was faulty? Did it explode?
salviador:
Except for that resistor, everything else shows no signs of burning. If I power it it doesn't turn on I checked with an oscilloscope and the mosfet (output pin8) has no pulses but it is not shorted
Harry_22:
I have the same problem but it occurs time to time.
In case of failure the voltages are:
FB=0
VIN=24.7 (I have 126VDC source) 
VDD=17.25
others zero

But FB shouldn't be zero. Zero volt on FB stops working.
It turned out that one-time heating of the controller restored its functionality.

Did you measured resistance from FB pin to ground? I mean optocoupler C-E resistance.
Harry_22:
Starting the controller using a soldering iron.

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