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[Longwei K3010D] No output voltage and continuous current limitation

cmsydney 6942 4
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Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
  • #1 18239142
    cmsydney
    Level 14  
    Hi
    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
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  • #2 19141102
    faza1111
    Level 11  
    I had 3 damaged smd capacitors and changed all of them. Probably there was a bad series of all capacitors
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  • #3 20431213
    Mikrob
    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.
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  • #4 21361245
    lalanmadushanka
    Level 1  
    TopsHak laboratory power supply with digital display showing 0.00V and 0.00A on a table. >>18239142

    Added after 8 [minutes]:

    TopsHak laboratory power supply with digital display showing 0.00V and 0.00A on a table. >>18239142

    Added after 45 [seconds]:

    TopsHak laboratory power supply with digital display showing 0.00V and 0.00A on a table. >>18239142

    Added after 4 [minutes]:

    TopsHak laboratory power supply with digital display showing 0.00V and 0.00A on a table. >>18239142
  • #5 21361637
    Mikrob
    Level 18  
    I have long since mastered it , it was a factory error not soldering the SMD IC legs and after a few power-ups they simply burned up from sparking , the chip replaced with a new one and works without a problem .
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