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Helllllllllp !!!

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  • #1

    Helllllllllp !!!


    So i tore my homebrew apart to clean it up....new turretboard and all components, tube sockets, wire, but same trannys, pots, jacks, so fourth. Triple checked everything then checked voltages and fired it up and biased it. Sounded great, played it for a few minutes then turned it off to swap out a snubber cap across the V1A plate. Turned it on and the mains fuse blew. 2 more blew and I removed the cap and still it blows fuses with or without tubes. I can't afford 100's of fuses, so any idea where i should start looking? Schematic ..........

    http://i24.photobucket.com/albums/c39/dazco/amp3.jpg
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  • #2
    Ok, i found the problem, but before i start it up again with the new parts can someone tell me what could cause this? Both diodes on one side of the rectifier were shorted. Any thoughts? Could it be the iron on the B+ too soon after the amp was shut down when i swapped that snubber?

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    • #3
      What type diodes are you using there?
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


      ​

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      • #4
        4007's. I'm pretty sure it was that i hit the turret with the iron too quick. I guess thats what those ESR(?) irons, or whatever they're called are for, eh? Anyways, i just went ahead figuring that was it and it works fine.

        You guys gotta be faster.....you're forcing me to learn this shite myself, THEN what will you have to spend your free time doing? (man, we need some serious ROTFL smilies)

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        • #5
          Hmm, maybe that's why the old solder station I acquired many years ago had the ground pin removed on the ac cord .
          Butane irons are nice for that reason, especially if you have to solder something that can not be powered down .
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


          ​

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          • #6
            Originally posted by g-one View Post
            Hmm, maybe that's why the old solder station I acquired many years ago had the ground pin removed on the ac cord .
            Butane irons are nice for that reason, especially if you have to solder something that can not be powered down .
            Good idea. Simplest idea, yet i never though to do it. Now....wheres that con sarn ground lift plug.......

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            • #7
              Or you simply had a diode failure. WHy try to come up with involved scenarios? I have never had a static failure on a 1N4007 or anything like one. This is a tube amp, none of this stuff is sensitive to static. Parts fail.

              The cap across the V1 resistor didn;t cause this. Even if you grounded off that resistor, there are still 30k between B+ and that point. SO at most a short to ground there would draw maybe 10 or 15 milliamps. If you somehow dropped a solder bead grounding off the main B+, and I mean back at the choke, then maybe.
              Education is what you're left with after you have forgotten what you have learned.

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              • #8
                Originally posted by Enzo View Post
                Or you simply had a diode failure. WHy try to come up with involved scenarios? I have never had a static failure on a 1N4007 or anything like one. This is a tube amp, none of this stuff is sensitive to static. Parts fail.

                The cap across the V1 resistor didn;t cause this. Even if you grounded off that resistor, there are still 30k between B+ and that point. SO at most a short to ground there would draw maybe 10 or 15 milliamps. If you somehow dropped a solder bead grounding off the main B+, and I mean back at the choke, then maybe.
                Ok, then maybe a simple failure. But i figured it was what i did because thats when it happened. In any case, thanks.

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