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Legacy 100 has low volume, shuts off

Posted: Mon Jun 24, 2019 3:55 pm
by Hollywoodbadguy1
Hey everyone.
First time post.
I'm Frankie Ray.
Just picked up a used legacy 100 head and half stack at an auction.

Have set it at 50 w 8 oms
And 100 w. 16 one.
Either setting there is sound but not even what a 25 w amp would make. Then about 5 min in it trips the 3 amp breaker in the back and shuts off.
I opened it up all toobs are lit but I think dim.
They are the EL34 TOOBS.
ANY IDEAS?
I AM UNABLE TO GET ANY VOLUME OUT OF IT. MAYBE 5 OR 10W.
THANKS.

Re: Legacy 100 has low volume, shuts off

Posted: Tue Jun 25, 2019 2:21 am
by ruger9
The first stop is always the tubes. I suggest replacing the EL34 power tubes with new ones (or at least known good ones). IDK if the Legacy require them to be re-biased or not, usually the answer is yes.

After that, if it has a tube rectifier, replace that.

It could be a tube going bad, but not completely bad yet, that is arcing inside or something, and causing the breaker to trip (which is a good thing, because that keeps components from blowing).

Re: Legacy 100 has low volume, shuts off

Posted: Tue Jun 25, 2019 8:58 am
by Hollywoodbadguy1
Hey thanks for the reply, should I have all the tubes tested before replacement? Or the rule of thumb, one going bad all are old.

Re: Legacy 100 has low volume, shuts off

Posted: Wed Jun 26, 2019 2:46 am
by ruger9
If it's a power tube (EL34) replace them both (or all 4, not sure how many the Legacy has).

If it's a preamp tube, you can replace just the one that's bad.. but from your description, I'd bet it's a power tube. If it were me, I would replace all the power tubes, and see if the problem remains. If it does, then replace the rectifier tube (if it has one). If the problem remains, start replacing the preamp tubes, one at a time. If after all that the problem remains, take it to a tech.

I suspect a power tube, because they wear out much faster than preamp tubes do. I replace power tubes about once a year (when they start getting noisy), but only replace preamp tubes when they go bad (far less common).

But as I said before: that amp might require the power tubes to be re-biased when you replace them, so unless you know how to do that yourself, you may end up at a tech anyway.

Re: Legacy 100 has low volume, shuts off

Posted: Wed Jun 26, 2019 8:34 am
by Hollywoodbadguy1
Thank you Ruger9.
Really appricate your time and insites.
FR.