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Thread: DC Fuse keeps blowing

  1. #1
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    Default DC Fuse keeps blowing

    I played a lengthly session the other day with some potential new band mates. I used the Lead channel a lot, we probably played for 3 hours.

    I played the Sig yesterday (last time played was Saturday), and after about maybe 10 minutes the amp kind of lost power and I got no signal. After looking at the manual, I saw that it suggested checking the DC fuse if you get no sound. I did, and sure enough the fuse was blown.

    I went to Radioshack and got some 1Amp 250V Fast-Acting fuses. Put one in, amp worked and I was back to playing and then after 5-10 minutes, the same thing happened; blown fuse.

    After thing the manual mentioned was to check the tubes for any failures. I noticed that when in Low Power mode, there was a little bit of humming. I took the tube out and examined it - I don't have a tester, but I got a used but tested good 5u4g from my amp tech.

    I took the chassis out, popped in the new tube, biased the amp and played it for about 15 minutes or so and then the fuse blew again.

    Any thoughts? I contacted tech support but no response thus far.

    I already had to send my Sig down to Fryette not too long ago and I really don't want to have to do that again.

  2. #2
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    Default

    Could well be one of the power tubes shorting - not sure on the sig tube layout 2x kt88s ? I'm guessing the one you replaced is for the rectifier .. .

  3. #3
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    Test each tube individually / one at a time.
    Take out one tube at a time and replace it with a tube you know works properly.
    Like said.... It might be a powertube.
    The fact that Stephen appears from nowhere, is sentenced to death in an emotional public trial without anyone interfering at all and is then altogether forgotten as if nothing happened, is already suspicious.

  4. #4
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    agreed, power tubes.
    Ultralead
    D120H
    Sig X
    Fat Bottom 4x12
    D412
    Valvulator I

  5. #5
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    Yep, my money is also on power tubes, have had this happen myself. take the back off the amp and play it in a dark room looking at the tubes, you might see one light up suddenly and the sound *should* be affected when it does. Either that or change out the pair for a known good pair.

    Pittbull G100UL
    Deliverance 60
    Fatbottom 2x12

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