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Carvin Sx-200 blown switching power supply

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  • Carvin Sx-200 blown switching power supply

    I have a carvin sx-200 with a blown power supply. The viper100 has left a nice dark trail on the heatsink and the surface mount resistor next to it (R1) is cracked and open circuit. From the few other posts I have seen on this Amp, it looks like the optocoupler should also be replaced for good measure. I have checked the TIP142/147 power transistors in-circuit, nothing's a dead short, but I am seeing the diode check voltages of half a volt or so in both directions on one of them. I guess that I will have to remove them to get a final verdict.

    R1 is not marked on the schematic. The part appears to be marked "5601", I assume that is 5.6K? Seems to be in the correct range, given the viper100 sample circuits on ST's website.

    For reference, here's the schematic:

    http://carvinimages.com/schematics/80-03201RevG-3.pdf

    Does it sound like I've covered the bases? Something made this supply go poof, but I'm not seeing a guilty party. I suppose that it could have suffered a brownout on the mains...

    thanks for reading.

    Dave

  • #2
    The schematic appears incomplete, the switching circuit is mossing, I assume the five VIPER references connect to something.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Originally posted by Enzo View Post
      The schematic appears incomplete, the switching circuit is mossing, I assume the five VIPER references connect to something.
      Yes, the VIPer100A-E switcher part:

      http://www.st.com/web/en/resource/te...CD00070231.pdf

      Same amp, similar situation as this post (you and Mr. Fahey were very helpful):

      Rebuilding a Carvin SX-200

      After I re-read it, I see that I missed checking the diodes, so I checked them and they look good.

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      • #4
        Remember, TIP142/147 are darlington transistors, which means two transistors inside, so the base to emitter will read as two drops.
        Education is what you're left with after you have forgotten what you have learned.

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