I have a '70 Ampeg V4 that popped a 7027A, who's socket is wired to the balance pot. The tube died when I turned cranked the treble while playing guitar, caught fire at the base between pins 2&3. The balance pot is also toasted.
If I substitute the pot with a 100R pair between the heaters, do you think another tube will blow? And what's up with the higher frequency causing this?
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RAPTOR 700R
V*4 balance
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soberskipper
- Posts: 36
- Joined: Sat Mar 29, 2008 6:55 pm
- Location: St. Augustine Florida
V*4 balance
Last edited by soberskipper on Tue Feb 22, 2011 3:00 am, edited 1 time in total.
Re: V*4 balance
Becareful v4's are prone to issues like this the pcb peals up and the voltage is so high it archs. Make sure the parts that burned are really the place that failed. Becareful when soldering get on and off fast to prevent trace peals.
Great sounding amps! Just sensitive to heat
Great sounding amps! Just sensitive to heat
My Daughter Build Stone Henge
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soberskipper
- Posts: 36
- Joined: Sat Mar 29, 2008 6:55 pm
- Location: St. Augustine Florida
Re: V*4 balance
Everything else is checking out fine...
A second tube was destroyed in the same way, same socket so I have to stick with the arc theory.
I can see that if the 545 Va arched over to the heater pin it would destroy the tube and anything else in its way (hum pot, tube socket) and this is what has apparently happened. Pin 2 had big solder globs due to the extra wiring for the pot. Am I correct in assuming that because it was a bigger target and the pin 2 socket may have been pushed closer to the pin 3 socket that this is why the arc happens here?
Does the amount of carbon build up in the socket make it a conductor for more problems? I easily chipped away the phenolic in between the pin sockets. Socket has been replaced with a ceramic socket and has been wired very carefully so that the pins are not close to each other, could this prevent the occurrence of the arc?
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SARDINIAN RECIPES
A second tube was destroyed in the same way, same socket so I have to stick with the arc theory.
I can see that if the 545 Va arched over to the heater pin it would destroy the tube and anything else in its way (hum pot, tube socket) and this is what has apparently happened. Pin 2 had big solder globs due to the extra wiring for the pot. Am I correct in assuming that because it was a bigger target and the pin 2 socket may have been pushed closer to the pin 3 socket that this is why the arc happens here?
Does the amount of carbon build up in the socket make it a conductor for more problems? I easily chipped away the phenolic in between the pin sockets. Socket has been replaced with a ceramic socket and has been wired very carefully so that the pins are not close to each other, could this prevent the occurrence of the arc?
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SARDINIAN RECIPES