I don't suppose you have access to an oscilloscope?
I suspect there is something that is reducing the duty cycle of the regulator to almost zero.
With the photos you've shown, I can't figure out how the optocoupler gets turned on only when the voltage hits the required value. Typically you'd have a zener diode or a TL431 in there somewhere. I can't see one.
I suspect there is something that is reducing the duty cycle of the regulator to almost zero.
With the photos you've shown, I can't figure out how the optocoupler gets turned on only when the voltage hits the required value. Typically you'd have a zener diode or a TL431 in there somewhere. I can't see one.