Ampeg v4-b problems

[Mr. Mügatu]

I have an early 70's silverface v4-b head that, when I was playing it last week at practice, ran into some problems. Just so you can get an idea of my setup, I play an '86 mij fender contemporary strat, through a tech 21 double drive pedal, and a fender 412 cab. So anyway, it started making this popping sound, so thought it was the cables I was using, but that turned out not to be the problem. The sound it was making was a hiss (like what it sounds like when you have too much overdrive) that would build up, and then break, and each time it broke, and made the popping sound, the power tubes would flash blue. I haven't turned it on since then, I'm afraid it might just get worse. I don't really know how to work on tube amps, and I'm working on a skimp budget these days, and my band is about to leave for tour on the 18th, so if I don't get this fixed before then, I have bigger problems. Any advice will help. Thanks!

[Wes]

When is the last time the amp was serviced and/or retubed?

How long has the amp been in your posession?

If you haven't worked with electronics, and specifically amplifiers,
I would not recommend this amplifier as a first repair/service project.

[Mr. Mügatu]

Originally Posted by Wes

When is the last time the amp was serviced and/or retubed?

How long has the amp been in your posession?

If you haven't worked with electronics, and specifically amplifiers,
I would not recommend this amplifier as a first repair/service project.

I had it serviced about 6-7 months ago, with all new capacitors and pots cleaned and such, except tubes, since the tubes were tested, and rated at about 98 percent, however they are the same tubes that were in it since I bought it about 4 years ago. The extent of my knowledge on servicing tube amps myself is replacing tubes, so if that's the problem, I could do that, but thats about it

[Enzo]

Unplug everything except the speaker. Turn the amp on and fire it up. Does it still make the noises with nothing plugged into it. I am betting it does.

Flashing inside a tube is almost always a sign of a bad tube.

My first reaction is failing power tubes. Pops and crackles are classic signs of failing power tubes.

Tube testers don;t tell you if tubes are about to fail, all they can do is tell you they conduct current.

It never hurts to have spare tubes anyway, so I would try a new set of power tubes.