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Dynasty 200SD low buss voltage

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  • #76
    Originally posted by paulstef View Post

    I had to register on this forum to do one thing. To say THANK YOU!
    I was in the process of reverse engineering that PCB myself and was wondering why the flyback was only working occasionally.
    You mentioning that it needs Vbus operational was very helpful.

    It lead me to check where the 810V goes from RC1 on PC10. Found the first 750k resistor, part of the voltage divider of 3x750k, to be open circuit.

    You just saved me a couple of hours of troubleshooting. Thanks a lot!
    Glad it worked out!

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    • #77
      Hello Jon,
      I too want to thank you for all the investigation and documentation you have supplied. I have an older Dynasty 200DX that worked perfectly for years until it was returned to me non-operative.
      After sitting on a shelf for a long time I decided to try and fix it because I have a car restoration I am working on and my mig is not providing the results i need.

      Upon inspection I found the following damages on PC2:

      C10 - large capacitor, 5uf @ 1000V blown almost off the pc board.
      hole in pc board under what used to be C10
      C4 and C8 - 2 large buss capacitors show same blistering at the top you photographed
      C7 - small electrolytic shows some bulging.
      All diode tests pass EXCEPT the one you mention in post 11: RC4-6/8 and the C12/C13 point directly on the module. This fails (open).

      My first question is: have you put together any sort of schematic for the PC2 board?
      second: what would cause the roasting of C10 in such a manner?

      I am a EE, but not much experience with circuits like this, and I appreciate any help you can provide!

      Thanks,
      Thomas

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