Keep blowing fuses...

[mackenziedeth]

I keep blowing fuses in the dual rectifier I just bought (used). The seller told me its more than likely a problem with one of the power tubes (he said thats 99% of the time what causes a blown fuse) but I was wondering what people here might think. Is there an easy way to check if a power tube is faulty?

 

[domct203]

The seller is right, most fuse failures are tube related.

Try this, set the amp on DIODE and remove the Rectifier (5U4GB) tubes from the amp. If the fuse doesn't pop it is most likely a Rectifier tube. If the fuse still blows, I would change the power tubes (always a good idea with a used amp anyway).

A tube could have been damaged in shipping the amp, let's hope this is not the reason the amp was sold in the first place.

Dom

 

[mackenziedeth]

Hm, ok. Well, I have been trying different tube combinations (taking the middle ones out to try as few as possible) with using the silicon diodes, and twice it didn't work. Ill try the other combinations tomorrow and if it doesn't work, then I don't know. I guess I'll have to take the amp in to a tech.

 

[domct203]

When troubleshooting the rectifier tubes be sure to remove them. Just switching to Diode is not enough. A faulty rectifier tube left in the amp will still blow fuses even when the amp is set to diodes.

Dom

 

[mackenziedeth]

Ah, great info. Thanks a lot I'll definitely try that if I can find some fuses.

 

[mackenziedeth]

Oh by the way, in case it is my rectifier tubes that are the problem (which i very much hope is the case) are they expensive? How much would a pair run me?

 

[songrider]

What tubes are in the amp? 6L6? El34's? and what rectifiers? 5U4GB or GZ34's?

 

[mackenziedeth]

6l6s and 5U4GB. I didn't even realize there were 2 types of rectifier tubes... I'm really learning a lot from having a real tube amp. Even if its frustrating as hell right now.

 

[songrider]

Well everytime I get a used amp I always re-tube it with new ones so I know exactly whats in there and that everything is new and right.

Personally I use EH 5U4GB Rectifier tubes in my dual rec. They have always worked like a charm in mine and arent as expensive as the Mesa branded ones.

I also only use Mesa 6L6 power tubes. I know they will be right and I dont have to sweat the bias. They cost a little more but for the peace of mind and the warranty to me they are worth it.

As for the preamp tubes, the world is your oyster... so many flavors to choose from... I use the stock mesa's in V1 - V4- V5- and tung Sols in V2 and V3... this combonation just works for me.

You can go to the Mesa website and order tubes there and also dougstubes.com as well as eurotubes.com .

I just dont recomend the GZ34's that Bob at eurotubes recomends. They made mine pop a fuse and I promptly removed them and went with the EH5U4GB's

A matched quad of power tubes from Mesa will run roughly 90 bucks... rectifiers from them roughly 20 bucks each...

Good luck! and make sure your bias switch on the back matches the power tubes you have installed!

 

[mackenziedeth]

I took out the rectifier tubes and set it to silicone diodes and presto! I'm in mesa heaven right now. This is amazing. Thanks for the help!

 

[domct203]

I took out the rectifier tubes and set it to silicone diodes and presto! I'm in mesa heaven right now. This is amazing. Thanks for the help!

Glad you got the amp up and running .

Either the Mesa or Electro Harmonix 5U4GB is a good replacement.

What tubes are in the amp now? Are they Mesa's?

Dom

 

[mackenziedeth]

There are 2 mesas and there are 2 from a place called "Tubestore" so thats the brand I guess. They don't really have a brand name on them that I can see.

 

[domct203]

There are 2 mesas and there are 2 from a place called "Tubestore" so thats the brand I guess. They don't really have a brand name on them that I can see.

Man, I advise you just retube the power section as well. You have no idea how old those tubes are (even the seller was blaming the blown fuse on them). Mesa 6L6 STR-440 are ok sounding, as well as the Russian-2 12AX7 (pre-amp), but there are better choices.

IMO the SED =C= 6L6 fit the Rectifier line perfectly. That's what's in my Roadster. I'm using the stock 5U4GB rectifier tubes.

Doug Preston at Doug's Tubes has some great selections of pre and power tubes. He has this 'basic' preamp setup that actually sounds good. IMO it's a great place to start with the preamp in the Recto line.

What ever you do, make sure you get the tubes from a vendor that knows how to match Power Tubes to Mesa amps (preamp tubes are pretty much plug and play with 12AX7's). There are many good vendors like Doug, Groove Tubes, and others. Tell them the amp you have and they will pick the correct tubes for you.

Have fun with it. Enjoy your new Rig !!

Dom