Help - No sound from my Uberschall

jc986

jc986

Member
Alright, hopefully one of you guys can point me in the right direction here. I was playing my Rev Blue Uberschall today and everything was fine. I went to switch to a different guitar so I put the amp in standby, and plugged in the other guitar. While still in Standby, I heard a crackling noise (almost like a shorted cable or something). The noise stopped after about a second. I flipped the amp on and now there is no sound whatsoever.

Does it sound like a fuse issue? I've been using tube amps for about 15 years and have been pretty fortunate not to really have ever had any issues other than a tube going bad. All the tubes still light up normally, but I'm not getting any output at all. Doesn't matter what channel. I bypassed the preamp by plugging straight in to the Effects Loop Return (leaving a cable connected to the input, as without something plugged in the amp is muted entirely) and still nothing. I swapped the V1 12ax7 with a known good tube and still nothing. I tried swapping in a known good set of E34L power tubes and it made no difference.

I suppose it's worth noting that I've been running KT88's for the last 6 months without having the amp's bias range modded, but per Charlie at Bogner it shouldn't be an issue as I ordered a very cool set of KT88's and they biased up easily to 34ma. So they aren't running out of spec and the Uber should be able to handle it per Bogner.

Thanks in advance for any other suggestions or if anyone can recommend a good amp tech within driving distance of Dayton, OH.
 
Seeing as how you tried the effects return and still got no sound, looks like a power section issue to me.

Unplug the amp.

Check the HT fuse, and if it's blown, DO NOT continue to use the same power tubes after replacing the fuse. It blew for a reason!!

Hopefully you have a spare set of tubes you can try.

If you put the spare set in and blow the fuse again, take it to a tech, unless you're really good with amp electronics.

If it works fine with the new power tubes, you have at least one blown KT88.

As long as the KT88's were biased properly, and it sounds like they were, the fact that you were running the KT88's should not have been an issue.
 
Cool, thanks for the input guys. I'll check the fuse tonight and report back. I do have a couple spare sets of power tubes that I know are good.
 
So the HT fuse is definitely blown. Ordered some fuses and they should be here by Saturday. I have a couple spare sets of tubes so I'll give them a go once the fuses come in.
 
leib10":85eawfkh said:
Yep, it's happened in my Ubers before. I keep several spares on hand now.
Click to expand...

Just out of curiosity, when this has occurred for you is a failed power tube the culprit, or just the fuse?
 
Just the fuse. It's happened when I used a power strip to plug the amp into and when I cranked the volume too high and too fast.
 
leib10":2dxdps6o said:
Just the fuse. It's happened when I used a power strip to plug the amp into and when I cranked the volume too high and too fast.
Click to expand...

While something along these lines is certainly a plausible scenario, and maybe I'm just overly cautious, but I would want to be 100% certain that those old power tubes were all OK before I would fire them back up in my rig. The last thing you want to do is damage the tube sockets, screen resistors, or in a worse case, the output tranny with a shorted tube or tubes.
UBER's can put upwards of 500volts DC on those power tubes.

Having said all that, I hope it's something simple and you're back up & rocking soon with no issues. :thumbsup:
 
Test the tubes, or invest in a tester. Such a useful and gratifying piece of gear when you want to make sure your getting the best tones possible. Tubes can make or break a good amp. Thanks for the reminder to order some fuses also. Something smart to always have handy
 
Yeah, I'll definitely use the known good tubes out of the gate. I don't have a tube tester. What do you guys recommend in that regard?
 
If you don't wanna break the bank and want something very easy the orange vt-1000 is great, to go above that your spending in the thousands and testing for thing like noise and microphones, gain level etc. I have the orange as I just primarily want to know if the tubes are running within the guitar amplifier optimum specs. It picks out bad, worn and unbalanced tubes for most of the major tubes used in today's guitar amps.
 
Thanks guys! Happy to report that after putting in the new fuse and a known good set of power tubes I'm back up and running again. I'll eventually invest in a tube tester to see if those KT88's are still okay, but my E34L's will work just fine for now.
 
Thanks for the offer, that's very kind of you. I'll hit you up via PM when I'm ready to send them your way. Might be a bit, as I'm gonna have to be out of town for a while coming up soon.
 
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