popping fuses...why?

[jtb226]

hey all. recently i've started blowing fuses in my DR and i'm not sure why. all my tubes, except for the rectifier tubes, have recently been replaced. i was playing in my apartment last weekend and wanted to try playing on the rectifier tubes, just to try something new. so i switched over to them and let the amp warm up, like normal. then when i took it off standby, the fuse blew and it shut down. so i went and got new fuses of the same type.

played 3 gigs on the fuse last weekend, then last night we were playing a gig and the fuse blew in like the third song of the 2nd set. any ideas? i know i need to replace my rectifier tubes, but i didn't think it would matter if i was playing on diodes? any suggestions?

 

[Barry]

hey all. recently i've started blowing fuses in my DR and i'm not sure why. all my tubes, except for the rectifier tubes, have recently been replaced. i was playing in my apartment last weekend and wanted to try playing on the rectifier tubes, just to try something new. so i switched over to them and let the amp warm up, like normal. then when i took it off standby, the fuse blew and it shut down. so i went and got new fuses of the same type.

played 3 gigs on the fuse last weekend, then last night we were playing a gig and the fuse blew in like the third song of the 2nd set. any ideas? i know i need to replace my rectifier tubes, but i didn't think it would matter if i was playing on diodes? any suggestions?

Tube problems can be intermittent . Maybe you have a power tube going bad

 

[simonich]

I think the rectifier tubes are still connected to the power supply even if you're using diodes. If they are bad (esp a short) they can draw a lot of current from the power supply. (there is another thread on this happening that I read this morning.) this might have something to do with you blowing the fuses (though it doesn't seem probable). I'd go ahead and change them out, then put in a new fuse.

 

[Platypus]

The Rectifier tubes are still in the circuit even in diode mode, I had this exact problem with my Dual Rec a few months ago.

Turn your amp around and put a new fuse in.. hit off standby and start playing really heavy low chords like E power chords or E string palm muting... watch for the tube that has the blue light show in it, that's your bad tube.

Have you noticed any sputtering or volume loss when you play low chords?

 

[jtb226]

thanks for all the information people. as always, it is greatly appreciated. i'm going to swap out both rectifier tubes, as they need it anyway. if it still keeps happening after that, i'll move on to try and diagnose the problem more. i don't think it would be a power tube, as i replaced all pre and power tubes last month.

 

[Barry]

The Rectifier tubes are still in the circuit even in diode mode, I had this exact problem with my Dual Rec a few months ago.

Turn your amp around and put a new fuse in.. hit off standby and start playing really heavy low chords like E power chords or E string palm muting... watch for the tube that has the blue light show in it, that's your bad tube.

Have you noticed any sputtering or volume loss when you play low chords?

Thats odd, I had a rectifier tube go bad in my RK last weekend and just switched it to diode and presto the problem went away .

 

[Russ]

Don't discount the power tubes as being bad even if they are recently replaced. You could buy them new and have a bad one right out of the box. Yeah, even screened tubes from time to time will exhibit this kind of random failure. The good thing is that because you are paying a premium for the screened tubes they typically replace them free of charge if they are bad out of the box or even within a short amount of time. I wouldn't worry so much about the preamp tubes in this case with exception to the PI tube possibly but that would even be a weird circumstance for it to cause the fuse to blow.

If your problem isn't fixed with new power tubes and rectifiers then it sounds like you need it serviced. It could be as bad of a problem as a tranny failing.

 

[Charlie]

Good info about the rectifier tubes. I was running my Stiletto w/diodes when I blew a fuse a while ago right after putting in new power tubes maybe it was one of the recto tubes. Didn't even think about that.

 

[Platypus]

Mike from Mesa gave me that little tidbit about them still being in the circuit in diode mode... that's odd Barry!

Also Russ is 100% correct, just because a tube is new doesn't mean there's not a problem with it. Follow the same procedure I mentioned above and see if you can get it to fault on you.

 

[jtb226]

anyone have any experience w/ EH 5U4's? i dont' use vacuum tubes much, if at all, so price is pretty much the most important quality as of right now for a quick fix. can get them for $12 @ tubedepot.com

 

[ThunderMonkey]

anyone have any experience w/ EH 5U4's? i dont' use vacuum tubes much, if at all, so price is pretty much the most important quality as of right now for a quick fix. can get them for $12 @ tubedepot.com

I don't understand what you mean by "i don't use vacuum tubes much, if at all" :? Don't you use them every time you crank up your amp?

I understand that price is important and $ IS tight for sure but quality should be your priority as far as your amp tone is concerned.

Don't skimp on the meat ! :lol:

 

[Russ]

You get what you pay for and better tubes aren't necessarily that much more. You just gotta know what you are buying. I certainly wouldn't make price over tone my concern. There again the rectifier isn't part of any tone circuit. It only indirectly affects your tone. It still can change it though.

 

[NoGlassNoClass]

anyone have any experience w/ EH 5U4's? i dont' use vacuum tubes much, if at all, so price is pretty much the most important quality as of right now for a quick fix. can get them for $12 @ tubedepot.com

Try pulling the rectifier tubes out of the amp, set it to silicon diode, and play for a while. If the fuse doesnt blow, then you know the recs are your problem.

You can run the amp safely without the rectifier tubes installed (in silicon diode) until you can get new ones.

 

[Russ]

NoGlassNoClass and Barry have a good point. You can run no Rec's in Diode to troubleshoot your Rec tubes until you get new Rec tubes if they are bad. Granted, it is the tighter Diode sound but at least you can get by until you get your new ones. I think that in Diode all that is going to the Rec's is heater voltage. Once you switch to Tube Rec it hits your Rec's with more voltage and switches the circuit to use them kind of like another little standby but you use the Diodes instead of getting nothing when not in Tube Rec mode.

 

[jtb226]

hey all. replaced the rectifier tubes today. seems to be all well. i pulled the old ones out (and i mean old). i never noticed before, but they were black on the inside around the bottom. like when a fuse pops how it turns black on the inside of the glass. i think what happened is that they failed and the fuse popped the second time.

after i put the new ones in, i played the amp loud for a good hour or so on tube rectifiers and on diode rectifiers and everything seems good to go. *knocks on wood* thanks everyone for the help.