Tube Amplifier turns on but makes no sound?

Question

I have a Bugera V22. Good amp, I've had it with 3 years on the road/gigging.
I turned it on, and in the middle of my set, the volume faded out and then it stopped sounding completely. I took it home, and I saw that a 12ax7 preamp tube was not turning on. I changed it out, but it still won't turn on. I swamp tubes around sockets, and it's the same socket that won't work. I opened up the chassis and it seems that all the soldering is good.
What should I do/check?

Answer 1

Hi, 'dog. Been roaming around the web for a bit here, not knowing about this amp. Consensus seems to be that it's an inexpensive yet very pleasing and muscular tube amp, dogged by some reputation for unreliability. Left off after unable to find exactly what had failed for some, other than several mentions of a crappy footswitch. Several noted a lack of any meaningful tech support/tech info, complicating repair. Perhaps you'll do better on a search, given more time.



Meanwhile, if performing, having a second amp with you is good. I toted two for years, after finding out early that a failure in mid-gig is no time to need a tech. If one went to the shop, a third then went with me.



The last amp tech visit was some years ago, to check out my vintage Fender (which had been through a brief 220v spike hitting our stage and survived). When I picked up 'baby, he noted that it was always a pleasure to work on them, as schematics were easily available, in complete contrast to then-new imports lacking that data, and using crappy components. Still have it, still cranking at nearly age fifty. My #2 most of the time? A Peavey, just built like a brick.



Best of luck on getting this resolved, as I bet it sounds great when it works.



EDIT: And Russell E just pulled a wabbit out of his hat! Copy that schematic, then take to a tech, waving it at him until he drools.



And happy holidays, and that to all the mob in this forum!

Answer 2

Yep, sounds like another component in the preamp has failed, causing the power to the socket to not get there.

This calls for a professional repair. Something probably overheated and burnt out.



OR...try checking the other tubes. Possibly another tube helps drive the preamp portion....



but I'm looking at the schematic right now, I see 6 tubes involved with the "pre amp heater" V1 V2 and V3

http://i1123.photobucket.com/albums/l552/asdain/Bugera%20V22%20Modding/bugerav22.png



and there are A and B tubes. (top section of schematic) so there is a lot of stuff that can go wrong there.

There are a lot of different voltages driving the tubes. I see 136, 138 160 153 175 and 199 volts. so there are a lot of resistors and capacitors. I don't see too many voltage regulators or transistors but there are a few,



Yep...take it in to be repaired. You've done everything you can to try and find out what it is. Now it's time for a pro to look at it.

You might try to look for a component that is cracked or browned or broken. look for a white ring like a splash ring around a part on the PC board. That would indicate that it "smoked out" .

Answer 3

Bugera V22 Schematic

Answer 4

If it "drained " out ,,could there be a bad capacitor in the circuit.

Answer 5

get a new one