Amp problem

[JeffB]

I have a cheap el34 2 ch amp. The lights are on but no noise except for.......it has a pulse!!!!??? once the tubes warm up and they pulse with it. The blue becomes more intense at the peak of the pulse. Ive tried different el34s same thing happens.

Ive tried different leads, guitars and speaker cabs. Any ideas?

Thanks

[slider313]

First of all, how old is the amp and what make and model? Does the amp have a tremolo channel?

Did it work well up to this point?

[JeffB]

new tube in 1st pos gave me sound but the pulsing sound continues???

[Steiner]

Take a good preamp tube and substitute it in to the first socket. If no sound, replace the original tube and swap out V2. Continue in that manner until the set is exhausted.

 

If it's still busted, ship it here. I have an excellent tech and will get it back to you by Christmas. 2012.

[JeffB]

First of all, how old is the amp and what make and model? Does the amp have a tremolo channel?

Did it work well up to this point?

Well its essentially a new amp although its about 7 years old. Its been used maybe three times for 10mins each time. Never once did it display any redeeming qualities. I fired it up last night and it worked fine. By fine I mean it produced sound and didnt have the 150bpm pulse.

Its a cheap nasty Ashton Viper 30. 2 EL34's and 4 12ax's. 2 channels. Reverb. No trem. Reverb on/off doesnt affect the pulse.

I have just changed all pre amp valves and it still has the pulse.

 

I discovered if I turn it off and put it away the noise stops.

[JeffB]

If it's still busted, ship it here. I have an excellent tech and will get it back to you by Christmas. 2012.

How about you dont ship it back.

[Steiner]

Well its essentially a new amp although its about 7 years old. Its been used maybe three times for 10mins each time. Never once did it display any redeeming qualities. I fired it up last night and it worked fine. By fine I mean it produced sound and didn't have the 150bpm pulse.

 

 

I discovered if I turn it off and put it away the noise stops.

 

We have a Winner!

 

I've read that caps can go bad if they aren't charged ~ annually. I'd venture to guess that. Crack her open and see if there are caps that spilled their guts. You might try the chop stick trick; with her on, poke about at the components with a chopstick looking for a loose solder joint.

 

As much as I treasure your posts here and would prefer to have the solution, I believe you're going to need a tech. With all new valves, it's got to be internal. That's good news though; you mentioned you didn't care for the amp. Perhaps the tech can mod it toward a style you prefer. Just in time for Thanksgiving!

[111518]

I discovered if I turn it off and put it away the noise stops.

 

Remove the guts from the cab. Replace the power cord with a good length of nylon rope. Now you have a perfectly functional boat anchor.

[JeffB]

We have a Winner!

 

I've read that caps can go bad if they aren't charged ~ annually. I'd venture to guess that. Crack her open and see if there are caps that spilled their guts. You might try the chop stick trick; with her on, poke about at the components with a chopstick looking for a loose solder joint.

 

As much as I treasure your posts here and would prefer to have the solution, I believe you're going to need a tech. With all new valves, it's got to be internal. That's good news though; you mentioned you didn't care for the amp. Perhaps the tech can mod it toward a style you prefer. Just in time for Thanksgiving!

 

 

Remove the guts from the cab. Replace the power cord with a good length of nylon rope. Now you have a perfectly functional boat anchor.

Two different approaches and yet both could work.

 

What size boat should I get?

[111518]

Two different approaches and yet both could work.

 

What size boat should I get?

 

12's are the industry standard, but I hear you get more rounded highs on a 15. Or some cats like 2X10s.

[slider313]

Well its essentially a new amp although its about 7 years old. Its been used maybe three times for 10mins each time. Never once did it display any redeeming qualities. I fired it up last night and it worked fine. By fine I mean it produced sound and didnt have the 150bpm pulse.

Its a cheap nasty Ashton Viper 30. 2 EL34's and 4 12ax's. 2 channels. Reverb. No trem. Reverb on/off doesnt affect the pulse.

I have just changed all pre amp valves and it still has the pulse.

 

I discovered if I turn it off and put it away the noise stops.

 

If the amp is AB push/pull you may have an intermittent problem with one of your power tubes.

Did you try replacing the EL34's?

[JeffB]

Happy ending.

Gave it to a kid down the street yesterday. His dad told me today the boy dropped it carrying it home. Works fine. No pulsing noise.

[pegleg32]

Happy ending.

Gave it to a kid down the street yesterday. His dad told me today the boy dropped it carrying it home. Works fine. No pulsing noise.

 

Ah yes!! My favorite repair tool - clumsy kids!!! They can fix anything. A good ending Tully.

[tulk1]

When I was a Printing Press Repair "Person" (yes, politically correct even waaaaaayyy back then) we always told them the problem was the nut behind the handwheel. And if they'd leave the little green switch alone they'd never have a problem with the press. Never thought of getting a clumbsy kid to work with us. That'd fixed 'em all for sure!!

[JeffB]

Im guessing a dodgy solder joint has been temporarily knocked back into place. Chances are he'll bang it again and knock it back out of place.

I told him no opening it up and poking around inside with a full warning of what may happen.

Either way, I got my lawn mowed and he got an amp.