Tube Amp Blowing Fuses......

  • Thread starter Thread starter Gidge
  • Start date Start date
Sounds like bad wiring somewhere in the amp (assuming, like other people suggested, that the tubes are all good/snug and the speaker cable's good). If it's blowing at power on, I'd assume it's a wiring fault pretty early on, and if the guy doesn't know how to find the problem, then I'm sure he can't fix it, so best bet is just to take it in somewhere reliable.
 
Imaduck said:
if the guy doesn't know how to find the problem, then I'm sure he can't fix it, so best bet is just to take it in somewhere reliable.
Click to expand...

yeah he's about as dumb as a bag of nails and frankly, just plugging in pushes his intelligence to the max......just looking for some obvious stuff to look out for......
 
Bummer power tubes are a really likely cause. It might be the speaker cable, but if the guy had it shipped to him, I bet it is the power tubes. If it is the speaker cable and this guy keeps replacing fuses, one time he's going to smell his output transformer barbecuing as it shorts out and catches on fire.

BTW don't ram a 20 amp fuse in there. Your amp will stay on, and maybe even sound good for about three seconds. Then you will get to go and shop for a new amp!!!Yay!

If putting new power tubes in and checking the spkr. cable doesn't help have someone who knows what they are doing take a look at it.
 
ok ...wel i think i figured it out,

when i unpacked the head unit (which really was packed very securely in an old marshall head unit box) one of the bigger tubes (of which there are three ) ..was actually loose and just sitting inside rolling around...i put it back in the socket ..then proceeded to blow all those fuses...then after some of you mentioned reseating ALL the tubes , i was doing just that ...and looking at them really closely...again THIS IS MY FIRST TUBE AMP ......and noticed that on the bottom of each tube is a 5 or 7 pin connector ..and in the middle of the all the connector pins is a little plastic "nipple" looking thing ..well when i worked my way back to the tube that had come loose i realized that little plastic nipple was broken off..in fact i found the other half of it inside the head as well.....man i hope thats it .....


fingers crossed*

sorry if any of you were under the impression i wasnt totally a moron ..
 
When that nipple (which actually is kind of a "key" on power tubes-only lets them go in one way) broke off it could have cracked the glass bottle, letting air into the tube- which means it's done. Take the tube with you to your store so they can give you the right replacement. They will probably tell you to replace both power tubes. They are right. They should be replaced as a pair. Look at that tube- you should be able to see if the glass is cracked on the bottom where the nipple is snapped off.
 
boingoman said:
When that nipple (which actually is kind of a "key" on power tubes-only lets them go in one way) broke off it could have cracked the glass bottle, letting air into the tube- which means it's done. Take the tube with you to your store so they can give you the right replacement. They will probably tell you to replace both power tubes. They are right. They should be replaced as a pair. Look at that tube- you should be able to see if the glass is cracked on the bottom where the nipple is snapped off.
Click to expand...


again thanks for all the help ...

now this tube is one of the three biggest tubes in the whole thing..so when you say pair....there are three of them "5UG4"....and roughly how much do these things cost???...
 
OK 5U4G is a rectifier tube, not a power tube (my mistake). It's a triple rectifier amp, right? Don't worry what that means, but I'll tell you if you want. The good news is you don't have to replace those as pairs, you can replace them singly. I thought there was 1 rectifier and two power tubes. They are roughly the same size. Sorry, my bad. Anyway, I've seen them anywhere from $17-$40 depending on brand. With rectifier tubes I wouldn't worry about tone, as it's not in the audio path at all. Just get one that works. Thanks for warranties! Sovtek, Svetlana, there are a few companies out there. Are you near a music store which might carry tubes?
 
boingoman said:
OK 5U4G is a rectifier tube, not a power tube (my mistake). It's a triple rectifier amp, right? Don't worry what that means, but I'll tell you if you want. The good news is you don't have to replace those as pairs, you can replace them singly. I thought there was 1 rectifier and two power tubes. They are roughly the same size. Sorry, my bad. Anyway, I've seen them anywhere from $17-$40 depending on brand. With rectifier tubes I wouldn't worry about tone, as it's not in the audio path at all. Just get one that works. Thanks for warranties! Sovtek, Svetlana, there are a few companies out there. Are you near a music store which might carry tubes?
Click to expand...

Yeah we have a couple places locally thankfully.

holy crap there i sa LOT of tubes in that thing ..yeah triple rectifier ..got it off ebay ...so im sooooooo glad that its hopefully JUST a broken tube ..and not just a bunk amp some guy unloaded on me ..so a single replacement tube should do it!....cool and THANKS again for all the help ..

and to gidge for posting this over here as well.
 
BTW if the tube isn't broken, you may just have put it in the wrong way. You can try to figure out the correct orientation by putting the nipple back on and seeing the right way to put it in. The tube may still work, tho putting all that juice thru it the wrong way may have fried it.

And when shipping amps, always remove the tubes, and ask the same if someone ships to you.

Have fun with your new amp. :)
 
would you beleive me if i said that upon further inspection i must have had it in the wrong way ...with the plastic piece being gone ...and not even knowing there was a specific orientation .....oh my god ....how fucking STUPID is that ..?~?~




sorry guys ...but thanks for all the help ...if you all hadnt offered advice i would be sitting here tomorrow with new tubes and still no sound..

Jamal
 
Don't get down on yourself. Look at it this way, man. You probably now know more about tubes than 90% of the people who own tube amps......
 
Jamal, do not buy any 5U4 tubes, I have a ton of them,... NOS, and used,.... Email me your snailmail address, and I will send you three to retube with,.... use em or not man, up to you,.... and just so ya know,..... as long as the glass is not broken,... the one that lost its orientation key is still good,..... you just had it in wrong,.....

Steve
 
You must log in or register to reply here.
Back
Top