Solved....for now...Edit- fuse may be OK Bad Tube? Best way to test?

[OldGtrGuy]

Edit- my audio "beep" function on my meter was off. Got that going and the fuse does in fact make the meter beep.


Never had this issue in my life so im just looking online at Google trying to find some info.

Set up for a gig this weekend, about to soundcheck and my amp cuts out. In and out a few times, thought it was my noise gate or something. Turned the amp off and on a few times, plugged straight in, took me a minute but I looked and saw all 4 power tubes not lit up.

Amp was on, all preamp tubes were lit up but no power tubes and no sound.

My hope here is a tube failed, the fuse blew and that is that. New tubes and new fuse on the way but im also pretty worried about something more serious.

Anyhow how should I check this out? I read online to plug one power tube in at a time and turn it off and on? Bunch of weird things like that which sounded sketchy.

I did check the HT fuse to the best of my ability and there was no beeping on the meter so I do think the fuse blew?

Here is a closeup pic zoomed in. The filament isn't completely broken but it looks like there could be some damage.

 

[Geo]

What kind of amp? Could be a broken solder joint. Check the power tube sockets.

 

[OldGtrGuy]

What kind of amp? Could be a broken solder joint. Check the power tube sockets.

Uberschall ultra

 

[Geo]

Uberschall ultra

If there is no continuity across the fuse, just toss it. That's a well built, somewhat sophisticated amp, tread lightly.

I would try to give the power tubes a little wiggle and see if you hear anything change.

 

[OldGtrGuy]

If there is no continuity across the fuse, just toss it. That's a well built, somewhat sophisticated amp, tread lightly.

I would try to give the power tubes a little wiggle and see if you hear anything change.

I won't turn it back on until the new fuse arrives but I did pull the tubes and they look like this. Not sure if this is normal but the rods look pretty fried to me.

 

[Geo]

I won't turn it back on until the new fuse arrives but I did pull the tubes and they look like this. Not sure if this is normal but the rods look pretty fried to me.


View attachment 436840

Yeah, I don't know. It could just be how it was constructed. Are the others the same way?

 

[OldGtrGuy]

Yeah, I don't know. It could just be how it was constructed. Are the others the same way?

Yeah they all look similar in the same exact spot too. I asked chat GPT and based off of my symptoms and my pictures the robot told me that the HT fuse is definitely blown and that power tube failure is exactly what happened. I hope the robot is right.

I got new tubes and a new fuse on the way so hopefully that solves my issue, thank you for the help

 

[LP Freak]

Hopefully it didn’t take out a screen resistor

 

[OldGtrGuy]

Hopefully it didn’t take out a screen resistor

Yeah ill be fucked lol. I just ordered a tonex one to have something to gig with for the emergency situation. There's no way id get anyone to fix something serious like that in time but going to start with tubes/fuse first and go from there.

 

[CDawg]

If a power tube doesn't go white from losing vacuum or show burn marks on the plates/glass I would try changing the phase inverter tube first.

 

[Geo]

It doesn't sound like a power tube to me.

 

[harddriver]

Fuse's can be bad without completely burning up, if the fuse shows no continuity it's blown. Also if one of your power tubes shorted out or partially shorted for an instant that would cause your HT fuse to let go. The HT fuse is in place to protect your Output transformer. You need to check every one of your power tubes first to see if they are bad if you can and possibly caused the HT fuse to let go.

DO NOT power up that amp until you know if those power tubes didn't have some type of a massive failure. If one or more is bad then you need to replace the power tubes and then install a new fuse before powering up again.

Unfortunately you can have failures like this with any Vacuum tube/tubes but new production ones can have a early mortality rate.

Some times screen grid resistors will be fine if the HT fuse popped quickly.

Are these JJ power tubes in this Uber Ultra???

 

[OldGtrGuy]

Fuse's can be bad without completely burning up, if the fuse shows no continuity it's blown. Also if one of your power tubes shorted out or partially shorted for an instant that would cause your HT fuse to let go. The HT fuse is in place to protect your Output transformer. You need to check every one of your power tubes first to see if they are bad if you can and possibly caused the HT fuse to let go.

DO NOT power up that amp until you know if those power tubes didn't have some type of a massive failure. If one or more is bad then you need to replace the power tubes and then install a new fuse before powering up again.

Unfortunately you can have failures like this with any Vacuum tube/tubes but new production ones can have a early mortality rate.

Some times screen grid resistors will be fine if the HT fuse popped quickly.

Are these JJ power tubes in this Uber Ultra???

I don't have a tester for the tubes unfortunately to know if any or all are bad.

These are JJ's.

The fact that the amp worked briefly, started cutting out then back in and out a few times, then went completely dead makes me think it was in fact a tube.

I looked on chat gpt and that said those are the symptoms of a tube getting ready to go out plus the fact the ubers have such high plate voltage, when the tubes go they will go fast.

Im really hoping this is the situation here. Worst case scenario I mail it to Bogner and pay whatever it costs to fix but my issue is I need this amp fast, have gigs lined up all month and I dont want to use the tonex lol

 

[harddriver]

I don't have a tester for the tubes unfortunately to know if any or all are bad.

These are JJ's.

The fact that the amp worked briefly, started cutting out then back in and out a few times, then went completely dead makes me think it was in fact a tube.

I looked on chat gpt and that said those are the symptoms of a tube getting ready to go out plus the fact the ubers have such high plate voltage, when the tubes go they will go fast.

Im really hoping this is the situation here. Worst case scenario I mail it to Bogner and pay whatever it costs to fix but my issue is I need this amp fast, have gigs lined up all month and I dont want to use the tonex lol

What is the plate voltage in the Uber Ultra? I find anything over 450DCV pushes new production tubes pretty hard.

 

[OldGtrGuy]

What is the plate voltage in the Uber Ultra? I find anything over 450DCV pushes new production tubes pretty hard.

Rumored to be 490VDC

Also after further review, I do not think the fuse is blown. Idk

 

[harddriver]

Rumored to be 490VDC

Also after further review, I do not think the fuse is blown. Idk

490VDC is not horribly high. I have a Musicman HD100 that has 700VDC on the plates........................

Even if your HT fuse didn't pop that doesn't mean your power tube/tubes were not having an issue.

 

[OldGtrGuy]

490VDC is not horribly high. I have a Musicman HD100 that has 700VDC on the plates........................

Even if your HT fuse didn't pop that doesn't mean your power tube/tubes were not having an issue.

I tested the tubes at pin 2 and 7 with my meter and no beeping.

I find it very odd that none of the 4 beep at all, was expecting at least one of them to read something.

Here's to hoping it is simply time for new tubes. My dumbass ordered JJs again because theyre cheap but this time KT77.

If it is just tubes ill probably switch brands tbh.

 

[harddriver]

I tested the tubes at pin 2 and 7 with my meter and no beeping.

I find it very odd that none of the 4 beep at all, was expecting at least one of them to read something.

Here's to hoping it is simply time for new tubes. My dumbass ordered JJs again because theyre cheap but this time KT77.

If it is just tubes ill probably switch brands tbh.

Did you buy this amp new? If so Bogner probably would send you a new set of power tubes. Maybe send them an email and ask them, they probably would arrive at the same conclusion but ya never know.

Tube failure is inherent to modern production vaccum tubes unfortunately, just ask Dave Friedman.

 

[OldGtrGuy]

Did you buy this amp new? If so Bogner probably would send you a new set of power tubes. Maybe send them an email and ask them, they probably would arrive at the same conclusion but ya never know.

Tube failure is inherent to modern production vaccum tubes unfortunately, just ask Dave Friedman.

Lol Dave is the reason I think i shouldn't buy JJs.

I did buy the Bogner used.

Years ago I bought a new JP2C and it had a dead power tube straight from the factory. Or at least it was dead by the time it got to my house.

I rarely have had power tube issues though

 

[harddriver]

Lol Dave is the reason I think i shouldn't buy JJs.

I did buy the Bogner new.

Years ago I bought a new JP2C and it had a dead power tube straight from the factory. Or at least it was dead by the time it got to my house.

I rarely have had power tube issues though

Dave is using JJ power tubes again as well a Reinhhold, Dave had a run of JJ failures in his amps a few years ago and he had to go EH for awhile. Any tube manufacturer can have an issue honestly but I personally have had more issues with JJ's over the years versus EH, Sovtek, SED, the old Svetlana but alot of people swear by them so YMMV.

I just admit power tube issues may be a problem and live with it. I've had alot of JJ's go into bias drift leading to shorting out and total failure.