Hello Classic 30 question.

[thadjanus]

Hello all new to the forum wanted to thank you all for sharing the wealth of information. I have a classic 30 that has started to have troubles. a week ago after having it on for a couple hours it started randomly popping. Yesterday while trying to record with it the popping had gotten so bad it was not able to be used. The sound has nothing to do with the guitar becuase it happens when it is unplugged. It sounds like someone is popping popcorn or the grand finale of a fireworks show through the speaker. THen it will stop and if I move the amp slightly or something triggers it (like a guitar) it starts again or it will just start up again in like 3-4 secon bursts. I took the chasis out and saw no hanging wires but didn't have it hooked to a speaker just thought it would bee something obvious. The tubes are a bit on the old side 4yrs maybe but the amp gets light use(a couple hrs a week)..
thought I'd post here to see if anyone had any experience with these sorts of symptoms and what areas I should look at for a possible solution.
THanks,
Janus

[acorkos]

could be one of a number of things....tubes are always the easiest and one of the first things to try.

This is a great resource for troubleshooting....
Tube Amp Debugging Page

[thadjanus]

Thanks for the link. I will buy some new tubes this week and see if that helps..

[Alex R]

turn down your master volume - if the popping sound doesn't turn down it's in your power amp (prob a tube); if it does it's in your preamp (try swapping in one new tube for each preamp tube in turn).

[Enzo]

And dim the room lights and watch the power tubes. ANy sparking or flashing inside any of them? That is a pretty sure sugn of tube failure.

And then inside the amp, the circuits are laid out on three circuit boards. There are rows of short bare-wire jumpers connecting the boards together. SOmetimes vibration causes these to break. SO we go down the row of jumper wires and gently tug up on each one. ANy that come free were broken and need to be repaired.

[thadjanus]

Thanks all I will try this tonight. Last night when it started I just tapped the tubes to see if I could trigger it. Seemed like no matter what tube I tapped triggerd a popping for a couple of seconds. Not sure if this proves anything exept that something related to the tubes is causing the sound. I am going order a complete set of pream and power this week and hope that might take care of it..

[Enzo]

ACtually it doesn;t quite do that. Tapping on the tubes also sends vibrations through the chassis and circuit boards. The tube sockets are mounted right to the circuit board after all. New tubes certainly won;t hurt, but do check those little wires.