Bugera 333xl-212 Issue AGAIN

[aisxos]

hello guys,
last week i had posted about my Bugera 333xl-212, that had taken a fuse.
So, i just bought another set of fuses popped one and tried it out. the Amp powered up ok, i tested the clean channel, all ok. When i switched to the lead channel distortion, i played just a little and with a flash, the amp stopped producing sound. I just assumed it had blown the fuse again and took a look behind the amp. What i noticed is that one of the 6L6 tubes had taken a white colour like dust being in it. What's wrong? what should i be doing? should i just pop another fuse or will i create more problems than i solve?

[acorkos]

white dust means the tube has cracked and lost vacuum. you should replace the pair of power tubes

[aisxos]

*news update*
i just changed the fuse again, gave it a go. amp will power up, standby wont work ( standby light is off ) and no sound. i m starting to freak out...

[guitician]

Did you replace the "White" tube that is bad?

[aisxos]

i didnt, i got no idea about biasing. i m a total amp newb actually. But the tube was already white before i popped the new tube, but it did play when i changed the fuse. the outpout for power says T 1.6AH 250v, the guy at the amp store told me to use a 7A fuse, which i did. i really hope that didnt fry the whole thing up. I mean whats wrong with it!

[guitician]

7 amp fuse for a 250v line? That is OK. I would test all the tubes first, then go from there. Isn't the old fuse marked? The amp should have the fuse value marked next to the holder. If your running on an odd number of tubes like three, because one went bad, your going to cause more problems if you dont fix what's wrong with the amp.

[aisxos]

you are quite right. The old fuse and the holder both have a notice saying T 1.6AH 250v. The problem now is that while the power light turns on, the standby one wont, and there is absolutely no sound, do you think that significant damage has been caused?

note: do forgive my poor english

[guitician]

There may have been a fuse inside for the high voltage(HT) that has blown. I looked at the manual for Bugera 333xl-212 and these are set to use EL34 from the factory and the switch next to the power transformer should be set to EL34. Are you using EL34 or 6L6 tubes?

[guitician]

The fuse is a 1.6 amp time delay type, if your line is 230 volts, depending on what country your in. If it had a 1.6 then thats what you should replace it with. But, then again, did you buy this locally or from another country? The amp should have printed on the back what line voltage it is made for. Some amps have switches for different line voltages, like 220/115. Yours may be set for a specific voltage.

[aisxos]

it says here 6l6 convertible to EL34. Theres supposed to be a switch inside that lets you use EL34 but i never changed them tubes or messed with them in any way, so they must be 6L6, since its already set from the factory ( i suppose ). i also looked at the manual but i cant see anything about another fuse, but as i said i m no expert

[aisxos]

i bought the amp from germany, i live in greece. it says on the back of the amp 230V, no switch, so i ll assume thats it. Basically, you mean i should have used another time of fuse instead of 7A? I ll note that, but still i m worried that i have caused some massive kind of damage to the unit, i dont know maybe i m exaggerating.

[guitician]

Your ok Greece is 220V. The manual usually won't tell about "Service" parts like an internal fuse, for safety reasons. I think you may as well take it to a technician for service. Unless you heard pop's, or smell burnt odor I think the amp may be easily fixed.

[Enzo]

A 7 amp mains fuse is just silly. At 220v, 7 amps represents 1540 watts. WAY more power than this amp needs. STick with the 1.6A fuse the amp specifies.

There are more fuses inside, and the fact your lights don;t come on is another indication that fuses inside are blown.

When powr tubes fail, it is quite common for them to take fuses with them. In a tube amp, bad tubes are by far the most likely reason for a blown fuse. Replacing the fuse won;t fix a bad tube. The bad tube will continue to blow fuses. You need a new set of power tubes.

Bias? Set it in the middle and forget it. You can have it adjusted more closely later.

[CharlieP]

A 7 amp mains fuse is just silly. At 220v, 7 amps represents 1540 watts. WAY more power than this amp needs. STick with the 1.6A fuse the amp specifies.

There are more fuses inside, and the fact your lights don;t come on is another indication that fuses inside are blown.

When powr tubes fail, it is quite common for them to take fuses with them. In a tube amp, bad tubes are by far the most likely reason for a blown fuse. Replacing the fuse won;t fix a bad tube. The bad tube will continue to blow fuses. You need a new set of power tubes.

Bias? Set it in the middle and forget it. You can have it adjusted more closely later.

Quit messing around with fuses. New Power Tubes NOOBS! Then check all your fuses internal chassis or take it for service is YOUR best solution. I don't think you are qualified to service it. You will only cause more damage or kill yourself.

[loktar]

Sorry for my english
Recently had this amp with quite a similar problem. The problem was - burnt protection diodes (2x 1n4007 and 2x r2000f) on poweramp PCB, so they simply shortened HV to the ground. Yes, it protects your output transformer if your speaker gone bad (or you are an idiot), but in't it dangerous a little bit?
Peavey-style anyway.