No sound from tube combo amp - amp tech was no help

[BleedingFingertips]

Hi there

So I have a Randall Diavlo all tube combo amp (40w). At some point, it just stopped producing any sound. Only the cooler was working, maybe even louder than usual.

So I brought it to Thomann here in Germany. A few days later I got a message that they didn’t find and issues and the amp was working fine (!) but they suggested to renew all preamp tubes due to some microphonic issues. I agreed since the amp is 8 years old.

When my Randall was ready I went to Thomann and tested the amp there, I brought one of my guitars and a cable. It worked fine.

BUT: half an hour later at home, the amp didn‘t produce any sound again.

The techs at Thomann couldn‘t provide any explanation.

did anyone experience anything similar? Is my power supply a problem if there‘s no malfunction in the amp itself?

 

[beaubrummels]

The only thing I can think of is if you have something plugged into the send/return loop at home that is cutting off the sound but wasn't in use at the shop.

 

[ehdwuld]

May be heat related

Over a time something heats and connection opens

 

[BleedingFingertips]

The only thing I can think of is if you have something plugged into the send/return loop at home that is cutting off the sound but wasn't in use at the shop.

No, I didn't plugged anything in the loop. Just guitar --> cable --> preamp.

 

[BleedingFingertips]

May be heat related

Over a time something heats and connection opens

I think it goes in the right direction but the thing is that there's no "over a time". You hit the power switch of the amp, wait for half a minute, hit stand by and enjoy the loudness of the cooler and the silence of the speaker if it's heat related then it seems the amp is "overwhelmed" right out of the power outlet in my house. Also it doesn't answer the question why the amp works fine when tested in another location.

 

[Securb]

did anyone experience anything similar?

My buddy went through something simular with his JCM600 combo. The amp would just die. He opened it up and changed a fuse and it would work for hours or days and eventually blow again. He took it to a top tech and they couldn't find anything but the blown fuse and swapped it out. A couple of days later it was dead again. Took it back to the tech and the guy said he was baffled. There was no reason for the fuse to keep blowing. This guy is the top tech in Boston and signed bands from all over New England use him. Yep, that band you are thinking of.

 

[Mincer]

Can you try putting a patch cable in the loop to see if you get sound?

 

[beaubrummels]

My buddy went through something simular with his JCM600 combo. The amp would just die. He opened it up and changed a fuse and it would work for hours or days and eventually blow again. He took it to a top tech and they couldn't find anything but the blown fuse and swapped it out. A couple of days later it was dead again. Took it back to the tech and the guy said he was baffled. There was no reason for the fuse to keep blowing. This guy is the top tech in Boston and signed bands from all over New England use him. Yep, that band you are thinking of.

If a fuse blows you'd have no power, so the fan wouldn't work either (I assume that's what he's calling the 'cooler'?). I have a Traynor with a fan on the tubes that blows fuses pretty regularly and everything shuts off. The fuse blowing in my case was partly related to caps needing to be updated, and the remaining problem might be transformer-related? (Not 100% sure on the latter, just going by what the service guy told me.)

 

[ehdwuld]

Can you try putting a patch cable in the loop to see if you get sound?

This

I had this with several amps
Bad or dirty jack in the efx loop

I keep all mine jumped when not in use


Can you plug in to the return and get sound?

 

[BleedingFingertips]

Guys, thanks for your insights and suggestions. My fuse wasn‘t blown. I haven‘t tried to get sound from the fx loop but it seems I don‘t need any more troubleshooting.

I tooked a chance and „fixed“ the amp by buying a power conditioner.

my hypothesis was that if the same amp (+cables, +guitar) reacts differently to different power outlets then I need to either move to another place or try to do something about the power in my house.

I had some doubts If power conditioner would cure the problem since folks orten seem to buy it to prevent hum/noise in the rig. But it worked perfectly in my case. Very strange, that my amp doctor didn‘t come up with the idea.

FYI, I tried the simplest possible device from Black Lion Audio:

https://www.blacklionaudio.com/store/power-conditioners/pgp/

But with European sockets of course. Never been happier with and other gear.

 

[Mincer]

Well, that's better than trying to track down an issue inside the amp. I am happy that fixed it!

 

[Securb]

Wow I went through something simular. I did not get no sound but a considerable drop in volume. I was wondering if it was a power issue. I ended up getting a plug into the wall voltage monitor so I could see in real time if issues I was having were being caused by voltage drops. It was the best $10 I have spent.

https://www.amazon.com/Eversame-80-300V-Voltmeter-Measuring-Household/dp/B015H0A3FO