Bugera 333xl-212 big problem

[Enzo]

OK, that helps isolate the problem. Nothing plugged into the amp but a speaker. Master volume will kill or bring up the hum. That means the problem is before the master volume.

Mastre up but ALL OTHER controls to zero. Hum now or not?

Now turn up the reverb control. Add any hum or stay same? Reverb back down.

MAster up, all others to zero. PLug guitar into FX return, turn guitar volume to zero. Hum or no hum?

Now lets pull tubes. Set all controls to some normal settings as if to play. I assume ther is hum. Pull V8, the first preamp tube. Hum go away or stay? Pull V7, any help? And since V6 directly feeds the master volume control, I have to assume that pulling V6 will kill the hum, but it takes just a second to find out, so do.

All these things help narrow down what part of the amp has the problem.

[raynman]

Enzo,
Sorry, I am new at this.
I have a post labeled "Bugera 333xl 60htz buzz" where I mentioned somthing new that happened yesterday. I will assume you didn't see it .
Anyway, after turning on the amp yesterday the buzz came on as usual, then it just stopped after about 10 minutes of playing.

I continued to played for another hour and a half (turning knobs and swithing channels back and forth, and I had a delay running through the fx loop) and the buzz never came back.

I will check it again tommorow and try your suggestions.
Thanks again

[Enzo]

Yes, I did see the other thread. As a rule we prefer not to have several threads about the same amp going, since it gets confusing. I made a response there at the time. Pick one thread and let the other die. My personal troubleshooting approach is going to be the same regardless of which thread it is in. That is the whole point of troubleshooting, it is a systematic skill. It all boils down to this:

Isolate the problem.


And if a problem comes adn goes, we call it intermittant, and that generally means a loose connection somewhere.

[Ronsonic]

I don't get it. I've worked on a number of Bugs and none were potted or painted. Just normal, modern Chinese production.

[Enzo]

No I have never seen them painted over either.

[pittsville]

Thermistor(s) fell out again

The amp works fine at home for practice. The two times it was taken to a gig, a thermistor jumped off of the circuit board. The second time, two of them decided to go.

I knew the first time I fixed the amp that the little board with the thermistors on it needed to be reworked. I'll be sure to do it this time before I put it back together again.

The build quality of that little board doesn't seem to match the rest of the amp.

[Robert M. Martinelli]

Well,
given the modern board soldering methodologies, and the progressive, but inevitable, switching to "lead free" solder (due to the "RoHS" rules and regulations), which maybe represents an improvement from an "environmental" standpoint, but,unluckily, sucks in performing its given task. Maybe I'm wrong, but I expect such problems to become more and more widespread as times goes by.

Cheers

Bob

[Enzo]

I would resolder ALL the thermistors on the little AC board.

I rather suspect the AC board was originally part of the main board, and they snap them apart at assembly, so differing build quality wouldn;t be an issue. Most amps that have a main board and smaller boards like for jacks or something, start out as one big board than snaps apart. On the other hand, if the leads on the thermistors were oxidized during manufacture, the solder may never have made a reliable contact. In my repairs, about the only thing I have t do to the Bugera amps is resolder those thermistors. Once done, they never seem to come back for it again.

[m0ls0n]

Bugera V22 vibrating buzz

Hoping someone who knows what they are doing can help me out. Here is the problem:
After hitting a master volume of about 4 (either channel) I hear a vibrating/buzzing noise(usually while a note is sustaining). Noise is coming through the speaker. I can tap the top of the cabinent and hear the same noise, although not as loud. Tap the tubes and hear the noise, although seems to come from the 3 AX areas.. I contacted bugera and someone from Germany responed to tighten all the screws. Though loose, after tightening I'm still getting that noise. I love the amp but guitar center isn't much help. I would like to take it for repair but want to give the repairman a good starting point.

Thanks for any suggestions,

Brian
Va. Beach, VA

[Robert M. Martinelli]

Hi Brian, and welcome to the forum!
May I suggest you to start a new thread rather than "hijacking" an existing one?
This will help in keeping the site in good order, and will facilitate searching through the site by keeping the topics separated.
Back to your problem, since it only occurs at rather high volumes, it seem to be "vibration induced", so it could be due either to a bad/cracked solder joint (this issue is going to become more and more common due to the use of "lead-free" solder) or a damaged preamp tube that has gone microphonic (though, if I was to bet my money, I would bet it on the first issue I mentioned).
JM2CW
Hope this helps
Best regards
Bob

[Enzo]

Because it is quick and easy, the first thing I would do would be look at those 12AX7 tubes, and tap on the side of each one with a pencil or your fingernail. If doing that to any of them makes a tink tink come out the speaker, try a different tube there, yours may be microphonic.

If there are thin aluminum shields over the tubes, remove those first.

[m0ls0n]

Bob,
I will do that next time. Thanks for the heads-up. I will check for cracks. Will the bad solder job cause the noise even if I removed the speaker from the cabinent? I could still hear the noise coming through it.

[m0ls0n]

Enzo,
Thanks for the response. I tapped them but don't get the microphonic noise. I pulled them out and placed them back in to make sure they were snug. Only thing I could tell is one of the white caps that the first 12AX7 went into wobbled a little. The prongs on the tube fit into them and the back of the cap is just solder. I've seen the prongs go through on other units. But, with the tube in it feels snug and there isn't any movement of it.

[Bones DeLa Crusher]

Bugera 1960 two minute life span.

Picked up the NEW 1960 from the FedEx shipping station, plugged it in an hour later, let it warmed it for a few minutes turned of the standby after setting presence hi mid and low to 12noon and... the sweatest sound ever heard (mostly) hung in the air for a few seconds and then faded into silence... WTF!!!!!???? Is this the same issue everyone else had? Do I spend another $80 shipping and 3weeks waiting to get it replaced? Or do I take my $80 to the bench tech and just get this fixed?

[Jazz P Bass]

The "new" amps have the heater connections hard wired to the PCB.
You "may" have an old stock unit.
Still, there are maybe 20 things that could cause loss of volume.