Got my Bogner - it's freakin BROKEN

sosomething

Seymour Duncan Customer Support
UPDATE:

I think I've got it working now. I followed the advice in this thread which was echoed by Bogner and my amp tech Kevin Silva when I called them.

I pulled the chassis and poked around the board with the amp on and running through a cab, trying to see if I could make any weird noises by prodding the solder joints, and I found one. It was a joint from a small wire that connected a piece of board under the pots to the main preamp board. It appeared that all the connections to the small board were made from the underside - likely before it was bolted to the chassis. From my angle I could see the edge of the wire all the way around so I added a nice smooth little blob of solder to it.

I then flipped the chassis back over and set it directly on top of the cab - just naked, laying there on the speaker cabinet with no head cab to protect it, and proceeded to vibrate my neighborhood.

No bad sounds.

Band practice tonight will be the true test. I'm tempted to remain skeptical just because of how easily I found the problem and how simple it was to fix - almost too good to be true - but I can't imagine generating more pure vibration in that chassis than I did yesterday with no problems.

Two interesting things:

First, this is the 95th Uberschall ever made by Bogner.

Second, Bogner scrapes and/or melts all the values off of nearly every cap in their amps. It's all top-secret, I must assume.

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Original Post Below
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AAAARRRRGH!!! :wrf:

I finally picked up my Uberschall from my old band's guitar player. I had it at band practice yesterday and was really excited to crank it up and get it dialed in. Let me tell you guys, through my Splawn cab, the Uber sounded amazing....

for about 5 minutes.

At any practical gigging / band practice volume, the OD channel started to kind of queef out on me under duress. Especially with palm mutes and heavier chords. Sort of an intermittent, farty / crackly sound coupled with a brief loss of output and gain. It actually sounds a lot like a bad output jack from a guitar or something, but that's not it. I used several guitars and cables, and had no pedals in the way. All jacks seem solid.

I don't know what's wrong with this thing. I need some help diagnosing the problem, if possible.

What it's not:
  • Preamp tubes - I replaced all the preamp tubes already in the amp with some spare EHs that I know to work. No improvement.
  • Power tubes - I replaced all the JJs EL34s with some Groove Tubes that I know to work. The problem was WORSE with the GTs. I switched back to the JJs.
  • Impedance. I used a good speaker cable that I know works and made sure my impedance was set to the proper 16 ohms and the amp was plugged into the 16 ohm input of my Splawn cab before ever powering up.
  • Guitar / Cables. I used both my Edwards LP and my Carvin CT and Planet Waves and George L's cables... The problem was there with all of them.
  • Pedals - The only pedal involved the whole time was my trust Korg DT-10 tuner, and after the first "WTF is that??" I removed it from the chain and it did not return. It wasn't the problem.

Facts about the issue:
  • Problem on OD channel only. Clean is fine.
  • Problem not present at low volumes, but once you get up to moderate practice volume it's real bad.

What's going on with my amp? I can take it to a tech but it'll have to wait for two weeks, and then it'll be gone for at least another two weeks - that's a whole month without my Uber and I don't know if I can bear it. :) If it's something simple like a bias adjustment that I can do myself, I'd much rather go that route but I don't want to go mucking around inside the amp without some reliable consultation on the issue first.

thanks
 
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Re: Got my Bogner - it's freakin BROKEN

its your power tubes. the yare biased too hot. with the GT's it got worse, that means they couldnt take it.

bias the amp.

but, could be a number of other things. does smacking on the amp do anything? does flicking the standby make it go away?
 
Re: Got my Bogner - it's freakin BROKEN

The stock JJ's tubes were recently biased by Bogner... and while I think it was worse with the GTs, it might just have been my perception since my ears were already very tuned-in to the issue.

I couldn't really tell if smacking the amp made a difference. It didn't CAUSE the bad sound. Smacking it might have made the bad sound go away for a second but it came right back.

Letting a heavy palm mute ring out caused the crackling sound to come & go while the note decayed. Playing very softly also made it more pronounced - almost like I had the volume knob on my guitar turned down to 0.5 or something. Then hitting the strings hard made the amp come back to life.

I swear it sounds just like a bad guitar output jack, but I know that that's not the issue for sure.

Would having the tubes biased too hot cause all this? Note that the clean channel sounds PERFECT. It's VERY clean until I have it cranked all the way up. I would think having the output section biased too hot would cause the clean channel to sound distorted or bad as well.

Thanks for the help!
 
Re: Got my Bogner - it's freakin BROKEN

ok. you gave more clarification. maybe not the bias.

is this amp new to you, or have you had it, and it just started doin it?
 
Re: Got my Bogner - it's freakin BROKEN

New to me.

It did the same thing for the previous owner - the other guitarist in my old band.

He sent it to Bogner - they upgraded the amp to the revision 2 Uberschall - but they apparently forgot to address the original issue. I suspect they never tested it at a loud volume, since this problem is nonexistent at anything short of full band practice volume.

I'm not really into shipping it back to California since the warranty period for the amp is well over now and there is a MORE than qualified tech in my area who I trust to do any work.

However, I would much rather fix it myself since cash is rather short at the moment and so is time. We have shows coming up and I want to use this thing.
 
Re: Got my Bogner - it's freakin BROKEN

I'm not a tech's butthole, but I'd put ten bucks on a dry solder joint or similar fault in the circuitry of the OD channel. Unlikely to be power tubes because that would be global and would affect the clean channel as well, which it isn't. You know it's not tubes, cables or guitar. The gremlin is in that OD channel's circuitry.



Cheers.............................wahwah
 
Re: Got my Bogner - it's freakin BROKEN

I'm not a tech's butthole, but I'd put ten bucks on a dry solder joint or similar fault in the circuitry of the OD channel. Unlikely to be power tubes because that would be global and would affect the clean channel as well, which it isn't. You know it's not tubes, cables or guitar. The gremlin is in that OD channel's circuitry.



Cheers.............................wahwah

Thanks man. Yet again you pop in with valuable insight.

Take it to the tech.

Called him. He's a rare kind of bird - willing to walk someone through a repair if they feel comfortable with it instead of taking money to fix something simple.

He's never short on work. Even The Nuge has had to wait a few weeks to get his stuff back. ;)

He seems to agree with Wahwah here.

His advice? Take the chassis out, plug the amp in to a cab and try to get it to make the sound. Then take a plastic pen and kind of poke around on the board to see if any spot makes it stop or makes it worse, and try to pinpoint the spot. Resolder and enjoy. He said that's how he would approach the problem.

I'm going to try this tomorrow when I see the amp again.
 
Re: Got my Bogner - it's freakin BROKEN

Not quite the same, but I had a similar thing going on with a Peavey Classic 30... one minute it might be fine... the next it would crap out, and as wahwah said... it was a dry joint (in my case at least).
 
Re: Got my Bogner - it's freakin BROKEN

having the same problem with my amp. now i think i'll try the pen trick
 
Re: Got my Bogner - it's freakin BROKEN

9 out of 10 amp techs and DIYers agree... the proper tool for poking around inside a live tube amp is wooden chopstick from a Chinese take-out place. I keep about a dozen of them in my tool drawer.

If you use a pen, make sure there is no metal on it anywhere.
 
Re: Got my Bogner - it's freakin BROKEN

Screw pens - chopsticks it is! I have a million of them at home.
 
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