Need Serious help! quickly! plz!

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monkeybar

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Ok! I have a triple rec, i have had it for 10 years and it has run flawless.... I have never changed out the tubes and it still sounds awesome.. until tonight when my other guitarist said he smelled something burning, and low and behold my amp had shut off :shock: .... I have checked the fuse and it looks fine... there is no unusual smells coming from my head unit., one of my band mates said that it could be a bad power supply due to the fact that when i go to turn it on I get nothing.. not even a red light saying that i am getting power... I know I'm in need of a tube replacement but even if my tubes went south I should at least still get a light saying I'm getting power right??? ALL AND ANY HELP is MUCH APPRECIATED!! I have booked dates coming up and and i cant have any down time right now.... If i can't rectify (no pun intended) this problem ASAP (within 24 hours) I'm going to go drop cash on a new combo amp... I don't want to, but I cant afford any downtime right now... SOOO PLEASE MESA GURUS!! HELLLPP MEEEE!!!! :shock:
 
There are internal fuses as well. You most likely have a blown power tube, I would not recommend putting new ones in yourself. You should get the amp checked just to make sure you didn't kill anything down the line for the power tubes.
 
XevKai said:
There are internal fuses as well. You most likely have a blown power tube, I would not recommend putting new ones in yourself. You should get the amp checked just to make sure you didn't kill anything down the line for the power tubes.


Not on Rectos. They have a varistor which acts as surge protection, but not internal fuses.


Fuses can be blown and not look like it. The only way to truly test a fuse is to check continuity with a meter.

You most likely had a tube blow. Pull the rectifier tubes, switch to diodes, replace the fuse and try it again. That will rule out the rectifier tubes. If it still pops the fuse, most likely there is a power tube that is blown, and it will probably require the attention of a tech to make sure you don't have something else wrong. When a tube blows, it can sometimes take out the screen or grid resistors, and unless you know exactly what you're doing, it's not a good idea to mess around inside the amp. Sounds like that's most likely what happened, hence the smell of something burning.


Where are you located?
 
I'm located in Maine.
I'll replace the fuse and switch to diodes to see what happens... the smell was very faint. in fact i did not smell anything (other guitarist did) and what ever smell there was it went away very quickly... when you say replace the power tubes what tubes are you referring to? the 6L6's? I was just going to re-tube the whole amp my self, are you suggesting to have a tech do it?
 
Yes, the 6L6s. Make sure you pull the rectifier tubes when you switch to diodes. If you have a bad rec tube and just switch to diodes without pulling the rec tubes, the fuse will still blow because the rec tubes are still trying to work. They're the 3 tubes on the far right, looking at the back, just in case you don't know....the 5U4s.

Try the rectifier tubes first, and if the fuse still blows, then it would be wise to take it to a tech and have them look it over, since there could be more wrong than just the power tubes. If you blew a resistor, it will throw the bias off on the other tube in the pair and could cause more damage.
 
ok.. so if I pull the rec tubes.. switch to diodes. put a new fuse in, and have power with out blowing the fuse
then I can go ahead and re-tube the amp and be good to go right?

With the rec tubes pulled will i be able to still plug in and play?


FYI- my tubes are 8-10 years old and have never been changed... would u say that chances are good that a rec tube blew, and cooked the fuse?

Edit:
I just noticed that I have always played it on the Silicon Diodes (hi-power) setting.. so I just have to pull the rec tubes and replace the fuse to check the power tubes right?
 
monkeybar said:
ok.. so if I pull the rec tubes.. switch to diodes. put a new fuse in, and have power with out blowing the fuse
then I can go ahead and re-tube the amp and be good to go right?

With the rec tubes pulled will i be able to still plug in and play?


FYI- my tubes are 8-10 years old and have never been changed... would u say that chances are good that a rec tube blew, and cooked the fuse?

Edit:
I just noticed that I have always played it on the Silicon Diodes (hi-power) setting.. so I just have to pull the rec tubes and replace the fuse to check the power tubes right?
definately change your tubes. i would think that be a good place to start. easy enough to do your self. let us know
 
Thanks all for the help.. :mrgreen:
it appears to be a bad Rec tube. so I'm replacing all of them and I'm good to go!
 
Good to hear that. It seems more common to blow a rectifier tube than a power tube. If you're using strictly diodes, you don't even need to replace them if you don't want to. You'll do the amp no harm by leaving them out.

I should probably take my own advice and pull them out of mine actually. I'm just begging for one of them to blow on stage one night. But, it draws attention....hey, look all those tubes! :lol:
 
There's an important difference between the 2-channel and 3-channel Rectifiers when it comes to the switching for the rectifiers - on the 2-channels, in solid-state diode mode the tubes are actually *disconnected* from the circuit by a 2-pole switch which removes the HT AC from the tube plates. This means that you *don't* have to remove the tubes to run the amp in solid-state rectifier mode if there's a rectifier tube fault - switching to solid-state alone is enough. On the 3-channels, the tubes are simply *bypassed* by a single-pole switch, leaving them in the circuit. This means that you must physically remove the tubes if there's a fault in one, since the HT is still connected and a shorted tube will still blow the fuse.

Likewise, on the 3-channel, shorted solid-state diodes (fairly rare, but not unknown) will make it impossible to run the amp in *either* mode, whereas on the 2-channel it won't because the diodes are fully disconnected in tube mode.

This change makes no difference to the operation when everything is working fine, but it makes a *big* difference to how survivable a tube or especially diode failure is, and the ease of troubeshooting it in a high-stress (ie gig) situation. Just to use a cheaper switch...

For what it's worth my Blue Angel (which does not have switching at all, since the two rectifiers are both in use all the time, for the preamp and power amp separately) blew a solid-state diode which left it inoperable without a bench job, so it certainly can happen and it would have been a major problem if it had happened at a gig - I carry spare tubes and fuses, but not a spare amp usually.
 

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