siemens sitop 24 vdc Smps outputs higher voltage 33 vdc

[CapLeaker]

This power supply is a hell to disassemble.

Ill try my best.

Yes, I know... some of them are a real pain to work on. But in this case I really do think there is a regulation problem as non regulating at all on the feedback and it also does make sense for the voltage to go to the upper limit. The squealing probably comes from the switcher not switching to the designed frequency of the transformer, loaded or not.

[PedroGG90]

Yes, I know... some of them are a real pain to work on. But in this case I really do think there is a regulation problem as non regulating at all on the feedback and it also does make sense for the voltage to go to the upper limit. The squealing probably comes from the switcher not switching to the designed frequency of the transformer, loaded or not.

After visual inspection , I can't see any optocoupler or tl431 . Or any feedback loop.

Only 2 optocouplers are driving signal from control board.

[CapLeaker]

Something has to tell the primary to how much power is needed,

[PedroGG90]

Something has to tell the primary to how much power is needed,

I need to search more.

[PedroGG90]

Something has to tell the primary to how much power is needed,

Hi again , i found two optocouplers , one of them seems to be the feedback one , it gets activated from 2 zener diodes coming from output rail capacitor

The other optocoupler gets activated from small control board but dont know where it goes after it.

[CapLeaker]

Hi again , i found two optocouplers , one of them seems to be the feedback one , it gets activated from 2 zener diodes coming from output rail capacitor

The other optocoupler gets activated from small control board but dont know where it goes after it.

Maybe post some pictures…