Problem with Mesa boogie Dual rectifier

[Lazarus]

Hey guys...


Yeah i got a problem , i was just playing guitar . And suddenly my amp just get switch of. Now i got no action from it at all. No light , nothing. I was wondeing if anyone has a clue what might have happend? It was working all fine, and suddenly it just got silent. . .

 

[Platypus]

If no lights come on then you blew a fuse, most likely caused by a power tube failure.

You need a 4amp sloblo style fuse, you can get them at any electronic shop. You need to read the manual and follow the tube failure section to figure out what happened.

No biggie

 

[Lazarus]

Is this hard fix, exspensive ?

 

[Platypus]

Is this hard fix, exspensive ?

Nah, I think I got 8 fuses for like 2 dollars locally..

Tubes are pricey but not unrealistic. Follow the manual to figure out which tube is causing the short (and causing the fuse to blow) in your amp.

How old is the amp and when was the last time you replaced the tubes?

 

[Lazarus]

The amp quite old i guess .. Bought it used, he said the tubes was new. So im pretty bumped. . So, you guys are sure it power tubes, what exactly is that?

 

[Platypus]

The amp quite old i guess .. Bought it used, he said the tubes was new. So im pretty bumped. . So, you guys are sure it power tubes, what exactly is that?

It's very hard to say anything is a sure thing with tube amps but it's a very common thing.

The power tubes are the 4 big guys on the back that are grouped together. The two rectifier tubes are slightly more to the right and closer together.

Tubes can just die for no reason, be it a day or a year old... that's just the name of the game.

Here is what I would do. Go purchase some spare fuses (You need a 4 amp sloblo fuse), always good to have them around. Put a new one in, turn the amp on and look at the back. Now keeping your hand on the standby switch at all times, flick the amp standby to on and watch the tubes in the back. Play a few heavy chords, strum, whatever, just get some juice flowing. If you have a bad tube you should notice a blueish flash like a lightning strike inside the glass. When you see this you will blow another fuse most likely but you'll have discovered which tube is causing the short. I've had power tubes and rectifier tubes go in this exact fashion so keep an eye on ALL of the tubes.

It might be in your best interest to buy a new matched quad if it indeed turns out to be power tubes but if you're slight on cash, find the mate of the other tube ( slot 1 and 4 are pairs, slot 2 and 3 are pairs.. so if slot 4 is the problem, you'll have to replace slot 1 as wel) and yank it too, it's always better to get a matched set than just a random power tube to replace it.

Good luck, let us know if you have questions. A new set of 4 tubes can go for as low as 48 USD stateside, however I cannot speak for Norway so your prices may be a bit higher.

 

[Lazarus]

Yeah our prices are way over. So thats a so thats a shame.

But I have question to what you said I should do.
I took the fuse out, and it looked ok. The chord inside is not cut. So when you say i should buy a new fuse, how would this help? If we are talking about the little fuse on the back of the amp , and not the big ones? Cause if the the little fuse back is not blown, how would a new one help? Thanks for you help, its kinda hard for me to explain in English . . So i appreciate all the help i can get.

 

[Platypus]

Yeah our prices are way over. So thats a so thats a shame.

But I have question to what you said I should do.
I took the fuse out, and it looked ok. The chord inside is not cut. So when you say i should buy a new fuse, how would this help? If we are talking about the little fuse on the back of the amp , and not the big ones? Cause if the the little fuse back is not blown, how would a new one help? Thanks for you help, its kinda hard for me to explain in English . . So i appreciate all the help i can get.

Well if the little fuse near the power cord is not broken then you have a different problem. Do you get ANY lights at all when you power the amp? Power light, channel lights, etc? If you still get no lights and the fuse isn't broken there might be something more serious going on. Might just be a resistor or something.. Perhaps someone with a more technical background can help.. I know one poster here is a Mesa tech.

Not sure if he's the one I am thinking of but Monsta-Tone does tube amp repairs and mods so perhaps he might have a better idea.

Here is his profile
http://forum.grailtone.com/profile.php?mode=viewprofile&u=941

You can private message him from that.

Good luck

 

[Lazarus]

The fuse is not broken. No lights whatsoever. I get nothing from the amp. . thats why im scared this could cost me.

 

[jbird]

Does anything else work out of the power outlet you are using? And, are you using some type of transformer?

 

[Lazarus]

Yes im using a transformer. To 220 V

 

[jbird]

And you have power?

 

[Lazarus]

No, the amp is not responding . .

 

[jbird]

Have you tried anything else from that power outlet? A light? A radio? To see if you have power from the wall, or transformer!

 

[Lazarus]

Yeah , everything else works. So i think it the amp.

 

[ytse_jam]

strange problem, i'm sorry but i cannot help you... however, if you're going to change fuse someday (the one near AC power cord), buy the right one for european AC voltage (220V). Don't know if platypus already considered you're european, suggesting the 4ampere one. Americans have lower voltages but higher current. In order to get about the same power reserve, we've got higher voltages and lower current, so an higher rate fuse than required will allow too much current flow in your amp!

 

[ytse_jam]

Yes im using a transformer. To 220 V

btw... TO 220 or FROM 220 TO 120?

 

[Lazarus]

Yes im using a transformer. To 220 V

btw... TO 220 or FROM 220 TO 120?

120 to 220 v

 

[ytse_jam]

let me understand... so are you in usa with your european amplifier?

 

[Jaroslav]

Well, If there is a transformer from 230 to 120 V (US model used in Europe), then the problem might lie in the external transformer itself. Is there any fuse on it? There is one on mine. Furthermore, there can be a thermal fuse in the winding - some of them are one-time only - that means, that after blowing a new transformer is needed.

One more thing, the fuse in the DR might look fine, but it can be broken at the same time. Have you tried to measure it? I've had some fuses, which are blown, but do not look as blown.