Bugera 1960 only runs on 2 tubes

Jerry_C

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Hey guys, I'm new to the group and have an issue with my Bugera 1960 head. I've been using and loving it for about 9 years. Suddenly 2 days before a show as it were, it crapped out. Power but no sound. After taking it apart and checking things I noticed I could hear what I was playing in the output transformer. I don't mean just noise, I could hear the chords I was playing, in a freaking transformer. This was a new one to me. Like a very weak busted hand held radio speaker. Was very low but it was there. I ended up finding 4 fuses in the output stage, 2 of which were blown. I replaced those and as soon as power was turned on, one of them would blow. So I tried running the amp on just 2 tubes and it worked fine. I cranked it up and no problem, other than running at half power. and it didn't matter witch tubes, 1&4 or 2&3, it still worked fine. Could the problem be in the output transformer? There was no swelled or blown caps, no burnt resistors, and no burned electronic smell. Just that weird playing sound in the OP transformer (No speaker plugged in) and that one fuse that keeps blowing. BTW, I ran tubes 1&4 in sockets 2&3, and tubes 2&3 in sockets 1&4 and and again thins were fine. To summarize: No speaker cab attached, I can hear guitar playing IN the output Transformer, and 1 fuse blowing when I try to run all 4 tubes. Could the output transformer be the problem?

Thanks for any heads up on this one.
Jerry
 
1 or two of your tubes are blown. Hearing the sound from the output transformer is perfectly normal. :)

I have a 1960 Infinium, it eats an EL34 once in a while, running at 10 for hours takes it's toll.
 
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i don’t have a variac and I think you would need one to trace the correct voltages plus the service manual. So I would take it to a tech.

Edit. I remembered looking at this Interesting video of someone that knows what they are doing looking for a similar problem.

 
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Do NOT play a valve amp without it being connected to a load - either a speaker, or some sort of dummy load, or loadbox. You will destroy the output transformer.

If it is working with two tubes, get through the show with that. Then take it to a tech.
 
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