Dual Recto problems

[madmesaman]

Hey guys, I'm new here. I bought a Dual Rectifier from a guy in Atlanta used. He put JJ tubes in, but wasn't sure of the time on them. The first thing that happened upon turning it on at home was a blown fuse. I think I forgot to plug in the cab though.

I replaced it and didn't have a single problem for about two months. Recently It blew the fuse I had in there. Ok, no big deal, maybe there was a power surge due to an overloaded circuit on the stage. I replace it, 4 minutes later and 2 minutes of playing time it blows again. I take it home, shake the tubes and it works fine for a few weeks. I get tired of the JJ tubes and since I still had 3 of the original tubes, so I put two of them in (In spot 1 and 4 as the manual says to do) after 20 minutes or so it blows another fuse.

The next day, I call Guitar center, they don't do work on amps, so I try another place, they won't pick up the phone.

I think I have an idea what it might be. My Guitar Teacher has had this problem before in the past with his mesa. It was a bad component inside (I think he said a Capicitor, but from what I'm reading here it's more likely a diode)

I replaced the fuse again tonight, and it just blew after 30 minutes or so of play time. There was lightning once, but I turned it on standby quickly enough not to blow the fuse. Played another 10 or so and it blew with lightning. I haven't noticed any noises and the tubes do not change their glow from the usual orange.

Any idea anyone?

*EDIT* I've blown fuses in both tube and diode modes, if that helps any.

 

[clutch71]

Did you pull one rectifier tube as well? Did you change the ohmage load to the 4ohm jack? Did you ever try other set of power tubes other than the JJ's to see if it still bew fuses?

 

[madmesaman]

Yes, I did pull a rectifier tube.

No, I didn't change the load to the 4 ohm jack.

Yes, I tried it with the original mesa power tubes, but they probably have more hours than these do.

 

[Gregwor]

Even though you have tried running the amp on diode mode, be sure to pull the rectifier tubes out as I've experienced rectifier tube problems blowing fuses even though the amp was set to diode.

Also, I'd replace the power tubes. There's a good chance that the JJ's aren't within boogie spec at which point they aren't biased right. In all my years of teching on Boogie, the only reasons the amps have blown fuses are due to either bad power tubes or rectifier tubes.

Again:
-Try it on diode mode with the rectifier tubes removed from the chassis
-Replace the power tubes with brand new Mesa tubes.

Good luck bud!

 

[madmesaman]

ok, thanks guys. I'll do that as soon as I can. I'll probably have a tech look at the insides anyway just be sure there aren't any other problems. I figured the tubes were the problems.

Thanks again!

 

[ne2i]

Just for information the folks at mesa are really great
They can hook you up with parts that you wont find anywhere
else. I bought a power transformer from them for 45$
Hit them up, you never know....

George
Rocket 44
repair service

 

[madmesaman]

Alright, newb question here.

Ok, I know the bias only matters on the power tubes. But when I replace them, should I go ahead and get the rectifier tubes as well, or will the JJs be fine in there? What about preamp tubes? will everything work alright with just new power tubes, or will that shorten their life, or cause malfunction or any sort?

Another newb question: The outer (1 and 4) tubes are matched, and the inner (2 and 3) tubes are matched, correct?

like I said, I'm a tube newb.

 

[clutch71]

You are correct on the matchings or you can buy a matched quad.

 

[NoGlassNoClass]

You can replace only the power tubes. If the rectifiers are good you wont have any further problems. If you pop another fuse change the rectifiers. FWIW I change the rectifiers and the V5 (phase inverter) preamp tube every time I retube the power section.

If you're blowing fuses in Diode mode with the rectifier tubes removed, then it's a power tube issue. If the recto's are still in the amp and one is bad, it will pop the fuse no matter where the switch is set.

Once you're up and running, if you hear odd noises like volume swells, helicopter/motorboat sounds, excessive squealing, problems with the FX loop, then look at the preamp tubes.

 

[madmesaman]

Thanks, that helps a ton. I plan on getting my power tubes by the end of the week, so I'll post if it's just the power tubes or if it's the recto/pre tubes too.

thanks again!

 

[madmesaman]

Sorry for the double post, I forgot to mention that the JJ recto tubes in it now are GZ 34 tubes, not 5U4GZ.

Should I switch back to the stock mesas before using it in tube rectifier mode?

 

[songrider]

In my opinion I would put all stock Mesa tubes in it before turning it on again. I have NEVER had any luck with JJ's in ANY Mesa amp yet. I tried the GZ34 rectifiers and mine blew a fuse. I was told it was because I had EL34 power tubes in it and to get a bigger fuse. Well I didnt and I just went back to all stock Mesa tubes and I am happy & it sounds and performs great.

The best advice I got about it was ;

They build them that way for a reason you know.....

And thats right!

 

[madmesaman]

The best advice I got about it was ;

They build them that way for a reason you know.....

And thats right!

no kidding. I just wish I had another $142 to spend on recto and pre tubes (tax is a killer here)

and I wish the previous owner had just stuck with mesas... oh well. with mesa, it's hard to beat $1700 for both amp and cab. :wink:

I only have 3 of the original pre tubes, and both recto tubes, but I am uncertain of how much life they have left on them....

I think I'll try it with the stock recto tubes in.... if it blows the fuse, then it blows the fuse... could be more bad tubes, could be something else.

thanks guys, I'll let you know how it turns out.

 

[madmesaman]

It's been working GREAT since I replaced the power tubes, no noises, blown fuses, or other problems, until a couple of days ago.

I put in the old 5U4GB recto tubes when I replaced the power tubes, as advised.

What do rectifier tubes do when they start going bad? Sometimes my amp makes a slight whooshing sound, and sometimes kind of a grunting sound (channels 2 and 3 for sure, I haven't heard it on the clean channel yet) when I play though. It may just be my guitar, because it only does a specific sound when I do bends and vibratos.

I've got a little bit of money, and I'm going to guitar center tomorrow, so I need to know if there is anything I really need to get. BTW the pre-amp tubes in it now are JJ ECC 83 s tubes.

Thanks guys.

 

[madmesaman]

Sorry for the double post.

I figured it out, it's either my FX pedal, or it's the number 4 preamp tube, because it stops doing it when either the FX channel is off, or the FX controller is off.

now I have a valid question: will the ECC 83s in there work with the 12AX7s alright, or will it be noisy, shorten the life of the pre tubes, or otherwise screw with it?

 

[V3]

ECC83's are the same as 12ax7, it is the European designation for our 12ax7. You can use any 12ax7, 12au7, 12at7 ect. But the at7 and au7 have less gain than the ax7 They will all work together though.