Bugera 333xl Troubleshooting?

[Vinny]

So I purchased a Bugera 333xl halfstack a few years ago (bad choice, I know), and it's definitely given me a bit of grief. But recently a new problem arose.

Basically, The amp just cuts out while I'm playing and switches to the clean (lol). It's kind of hard to describe. And it when it cuts out, it kind of farts at you as if you had turned the power off without first turning the standby on to let it cool down. But, when it cuts out, all of the lights stay completely on, except for the channel lights (the channel lights cut out for about a second or two, and then go to the clean channel as stated previously.) The problem starts after about 20-30 minutes of being on, and then gradually grows more frequent until it does it every 45-60 seconds.

Obviously, this is absolutely unacceptable, as this is the only amp I have as of now. I took it to Sam Ash, which is where I bought it, hooked up to my cab with all of the same cables and everything, and played it for well over an hour continuously and everything was fine. As I said, I brought my cab and all of the cables I use.

Then, I went home and it did it again. So this time, I just took it directly to the repair section of Sam Ash instead of first taking it to the guitar section as I previously did. They sent off to whoever repairs Bugera, took roughly 5 months (seriously), and then I finally got it back last night. Played perfectly last night, but I powered it up this morning, and within 30 minutes, it started doing the exact same thing.

What did catch my attention though, is that the amp gets extremely hot (it is pushed up against a wall in all honesty), so could that be the problem? It's about 4 inches off of the wall, because I really don't have anywhere else to put it. Are there any possible workarounds?

I need to know pretty soon, as my repair warranty expires April of this year.

Thanks guys.

 

[Mancha]

Are you sure it`s not a footswitch problem, cause it sounds like a problem Bugera V22 owners had with their amps. Without FS, they worked perfectly (and with another FS, of course).

 

[Vinny]

It does it with and without the footswitch plugged in.

I can't imagine it being something like that anyway, because it's not like it just switches to a different channel and that's it. It cuts out completely for about 2 seconds and makes that "farting" noise like when turn the power off without first turning the standby on. I'm afraid it will screw over my poweramp section. (But like I said, all of the lights are still on when it cuts out, so it's not a power connection issue...)

 

[Vinny]

Here's a video-
[ame]http://www.youtube.com/watch?v=_j6Hcwv4RvY&feature=channel_video_title[/ame]

 

[Vinny]

Sorry I wasn't able to play guitar and hold the camera up at the same time lol.
As I said earlier, when it switched channels it "farts" out and completely cuts out, and then comes back on the clean channel...

P.S. Creed FTW!

 

[PhilR]

I think the problem can be narrowed down to the fact that it's a Bugera.

After having seen the insides of those things I can't help but shake my head in mute pity for anyone that spent money on one. Sorry.

 

[Vinny]

Lol, yea I agree. I shouldn't have been such a cheapo and went with this.
But there has to be SOME fix to it...?

 

[Empathy]

But there has to be SOME fix to it...?

FIRE

 

[Vinny]

I appreciate the lightheartedness, but seriously. Anybody have ANY info on this?

 

[Vinny]

One guy suggested that I bias the amp to be a bit cooler.

 

[guitarguru777]

I think the problem can be narrowed down to the fact that it's a Bugera.

After having seen the insides of those things I can't help but shake my head in mute pity for anyone that spent money on one. Sorry.

I had to come back for this cause frankly it pisses me off all you DICKS who talk shit about Bugera. While they may not be the quality of the top name brands in amps they work just fine if you give them some TLC ....

The problem has nothing to do with it being a "Bugera". I have had mine nearly a year on over 100 shows AND over 300 hours of play time and I have ZERO issues.

Few questions.....


When was the last time you re-tubed the amp?
When you re-tubes it did you have it re-biased?
Are you running 6L6 or EL34's and is the Bias switch in the correct position?
Does it ONLY happen when the amp is "extremely hot" as you say?

 

[Vinny]

Everything is stock (Yea, stupid me, Don't have the cash to retube atm).
I have had this particular one for about 8 months, and is direct from the manufacturer (replacement because my other one just completely died on me.)
And I dunno if it ONLY happens when it is really hot, but when it does happen it IS hot (dunno if it is just a coincidence).

 

[Sloan]

It is very hard to troubleshoot amps when one is not actually there to poke around the inside. If it only happens when the amp gets hot, it may be something heating up and desoldering itself. This is fairly common, I've seen it happen in a JCM900 slx and some marshall mg stuff. The solution is the add a bit more solder or a heat sink to dissipate that extraneous heat.

If you don't have experience dicking with amps, I would suggest getting someone that knows how. It will most likely be expensive (typically $50-65/hr + $50 flat bench rate at shops).


There is a common issue with these amps involving a molex connector that can't handle the current running through it so it melts, causing intermittent then complete failure. One should remove the molex connector, and solder the wires directly to the pcb. This happened to mine before I bought, so I bought it broken for $200 and spent 20 minutes fixing it and have logged more than about 1500 problem free hours since.

Burned molex connector coming from power transformer to main board

Wires from molex soldered to main board


I have no problem with Bugera's build quality. I am working on amps and other music gear all the time as a side hustle and I was actually surprised for how organized and clean the 333xl was. The most problematic amps I have ever experienced were a Marshall JCM900 SLX and JCM2000 TSL. The 333xl is my primary gigging amplifier. I generally play two shows a week in a cover band for 4-5hrs each show. Then have two 4-5hr band practices a week. That's about 20hrs a week.

 

[Vinny]

Wow, thanks so much Sloan.
Can something like that cause the amp to cut in and out?

 

[Gonzo666]

no..if the molex conector melts, the amp switches on but the tubes don't start to glow and you won't get any sound out of it. I had this issue last week with my Bugera 6260...

 

[PhilR]

I had to come back for this cause frankly it pisses me off all you DICKS who talk shit about Bugera. While they may not be the quality of the top name brands in amps they work just fine if you give them some TLC ....

I talk shit about them because they're one-trick pony amps built from the cheapest components money can buy. I think that they're little more than a massive marketing con aimed at convincing people to waste money on pale imitations of popular brands that are simply NOT road-worthy equipment.

 

[Sloan]

Wow, thanks so much Sloan.
Can something like that cause the amp to cut in and out?

Is it just switching channels intermittently or is the output of the amp actually cutting out?

If it's just the channel switching issue, you might want to take the chassis out, power it up (with a speaker load!) and gently jiggle the relays. If you can duplicate the results of the problem consistently this way, then check the solder joints on that particular relay for cracks. If the solder is good, i would swap the suspected relay with another relay if available to make sure that one is definitely 'bad'.

If the actual amp output is cutting out, the first suspect would be tubes. It's always a good idea to have spare tubes around for troubleshooting and replacement. Also change the jack your speaker cable is in just to make sure the jack you use all the time isn't loose.

Behringer/Bugera will not publicly release schematics for their amplifiers, Bugera service centers have to sign a non-disclosure agreement. Since the 333xl is supposedly related to the Peavey JSX, you may be able to use the JSX schematic to get around inside the Bugera.

About the amp being hot - tubes get very very hot. I actualy have a mark on my arm from an el34 a few months ago. Burned enough to have it scab over and look real nasty. Ventilation is good for hot tubes, so don't cover up the top vent or other places where air can flow through.

 

[Vinny]

Is it just switching channels intermittently or is the output of the amp actually cutting out?

It's both actually. I honestly don't think that it is the tubes.
And I don't put anything on or near my amp that would cause it to overheat, except as I said, it is about 4 inches from a wall.

 

[Sloan]

Chopstick method
Use a non conductive item, such as a chopstick, to poke/tap around the amp and see if you can find locate the problem area. Then you just keep narrowing down until you find the particular part that is loose or faulty.


The fact that amp is cutting out and switching channels almost leads me to believe it's like a power connecter, but the lights stay on. I know it defaults to the clean channel when on. But those XL buttons stay on too, so i guess it wouldn't be that. I noticed that it's not an instant switch, which is kinda strange.

Does it switch BACK to the other channel with you having to press the button again?
Does it only happen on one channel or all of them?

It wouldn't hurt to go in and check every little connector to make sure they are not loose. They typically put hot glue on the connections which helps, but it's not 100% foolproof.

 

[Omega_Void]

...when it cuts out, it kind of farts at you as if you had turned the power off without first turning the standby on to let it cool down.

That's the main reservoir/filter caps in the hi-voltage supply discharging. Indicates they aren't getting any current to top them up.

Between those and the mains is the rectifier diodes and the power transformer, plus a fuse or two. There's a connection being broken in that chain somewhere.

...But, when it cuts out, all of the lights stay completely on, except for the channel lights...

So the amp is still getting current from the mains.

If it's problem caused by the amp heating up, I'd look for a dry solder joint, or a connection which isn't soldered at all. Check the clips in the fuse-holders are tight.

In some cases the circuit works fine until the expansion of the metal as it heats up breaks the connection; then it cools down again as there's no current flowing, until the connection is remade and the cycle starts again.

It may even be the action of a circuit that's designed to protect against damage from overheating, although if so it doesn't sound like it's working as intended.

If you can temporarily move the amp to a better-ventilated location, or maybe get a fan blowing into the gap between the amp and the wall. If better cooling makes the problem go away you can probably conclude it's a heat issue.

Another possibility might be flaky mains. If the caps in the hi-voltage are draining quicker than those supplying the low-voltage circuitry, a short interruption of the mains might cause loss of the hi-voltage while the low voltage circuitry still operates briefly.

Like Sloan said, it's difficult to make confident predictions without being able to poke around in the amp.

Good luck.