[Longwei K3010D] No output voltage and continuous current limitation

cmsydney 3873 2
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  • #1
    Level 14  
    I have a Longwei K3010D power supply. After turning on for less than a second, the fan is started and then it stops, the displays only show zero, the diode of the current limit lights up. No response to voltage and current regulation. Hear the sound of the coil (s) and it changes as the current is adjusted.

    The differences are cosmetic, the 10A version uses more powerful power elements. My power supply has a newer revision and there are some minor differences. Of the observed lack of Q8, Q9, Q10, W2.

    What I was able to check:
    - no short circuit on the output
    - power mosfets and schottky are operational
    - 12V is correct
    - VR and AR potentiometers are functional, properly connected to the board
    - U4 power supply ok, reference voltage approx
    - TL084 (instead of LM324) looks functional
    - there is zero on the SG3525 output (pins 11 and 14), hence the lack of a mosfet control signal
    - U4 pin 1 from 0.6 to 2.5V, pin 2 1.2 to 2.2V, both change with VR potentiometer, they do not respond to AR, pin 9 is 0.7V

    Where to look for the problem further?

    Power supply diagram:
    [Longwei K3010D] No output voltage and continuous current limitation
    [Longwei K3010D] No output voltage and continuous current limitation
  • #2
    Level 11  
    I had 3 damaged smd capacitors and changed all of them. Probably there was a bad series of all capacitors
  • #3
    Level 18  
    Hi , did you manage to fix this power supply , my friend wrote about damaged SMD capacitors , but it does nothing and does not explain , or maybe I just did not understand this answer . It's great that at least you found the scheme, it already gives a lot.