Blues Junior Buzzing

[Alowhitep]

Hi

I'm new to this forum and also quite new to Tube amps, i have my BJ3 about a year now. I never had a problem with it but I haven't used it for a few weeks and when i plugged it in yesterday its got a very ugly buzzing/crackling noise. I haven't replaced any of the tubes yet but i did swap them around, V1 for V3 etc, it doesn't make a difference. I'm gonna try replacing all the tubes tonight but just thought I'd put up a post here and see if anyone had any advice first.

Heres a few observations I've made on the problem.

1. The buzzing really only kicks in once i insert a jack, its doesn't matter if the Jack is connected to a guitar or not though obviously it changes the nature of the buzzing if it does.

2. When i hold the guitar the buzzing is much worse than if its on the stand.

3. When i play the buzzing goes away

4. With the volume and master down the buzzing goes away and it really only kicks in when turned up to 4/5 or beyond.

5. Turning down the Treble to zero almost completely eradicates the buzzing even at full volume, turning down the Mid reduces it and turning down the Bass or Reverb has no effect

6. Its slightly worse with Fat on.

7. My guitar probably needs the pots and jack input cleaned as fiddling with these can have an effect on the buzzing but i don't think this is the problem as the same buzzing is there when i tried a keyboard through the amp.


Any advice would be great guys cheers

[Leo_Gnardo]

Welcome aboard!

A common problem with Juniors is the solder cracking where tube socket pins pass thru circuit board. Perhaps this is starting to happen on your V1 tube socket, the one that handles first & second stage preamp functions. I can't explain that noises go away when you play, but worth a look and perhaps a reflow or replacement of those solder points with good ol' fashioned lead solder.

Those plastic input jacks like to come loose from the PC board too. A lot more hassle to get to, but same solution.

And 7) Yes do make sure your guitar's in shape first, before blaming the amp.

Also make sure you're using a shielded guitar cable in good working condition, and not a speaker cable which will buzz all the time.

[Alowhitep]

Cheers mate thanks.

I'm not much good with solder but i could recruit some help there im sure. Is it a difficult joint to get to? presumably i have to unscrew the PC board and resolder the pins at the back?

I'm going to try a few guitars and leads through it later and compare against a friends amp thats working well to try narrow down the problem.

The input jack looked fine too but I'll take a look again. Would it actually be wobbling? It seemed pretty solid last time i checked.

Anyway once again thanks for the advice.

[stokes]

Could be a lot of things,but I would check that its not just a dirty/loose tube socket.With the amp on and while the noise is present,try gently rocking the tubes in the socket,one by one,starting with V1.If you notice a change in the noise,it gets worse,gets better etc,could just be a dirty/loose socket.Of course it could still be a bad solder joint as Leo described,but at least you will have narrowed it down to a specific stage.

[Chuck H]

There is a duplicate thread for this in "tubes" that seems to be resolving.