All this regarding pin 6. I don't get why it's wired as shown. Since pin 6 isn't internally connected and is typically used as a mounting post for the screen resistor. There's no reason the shared lead to the #6 pins and the switch couldn't just go to the switch. And in fact the shared lead between the #6 pins seems like a vestigial appendage.?. That's a hell of a clumsy wiring scheme and lack of proper circuit knowledge for a $2600 amp. That being the case I have to wonder what else might be weird, and possibly wrong.
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"Half Power" switch problem
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"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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All this regarding pin 6. I don't get why it's wired as shown...#6 pins seems like a vestigial appendage.
How about this: perhaps the original amp didn't have the triode switch. The two 820 ohm resistors were soldered pin 4 to pin 6 on each socket the way a zillion Fender amps are wired. They added the switch, moved the resistors and just never removed the wire between the tubes. I'd buy that.Education is what you're left with after you have forgotten what you have learned.
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Originally posted by Enzo View PostHow about this: perhaps the original amp didn't have the triode switch. The two 820 ohm resistors were soldered pin 4 to pin 6 on each socket the way a zillion Fender amps are wired. They added the switch, moved the resistors and just never removed the wire between the tubes. I'd buy that.
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Originally posted by Valvehead View PostJust heard from the amp company-- the switch is not factory"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by Chuck H View PostIn that case, since you can't find what's wrong in the wiring or component functions you could just remove the triode switch, wire the amp stock and then test it. If it works you can wire up a triode switch. That way you'll be sure of the wiring and components. It's the long way around, but if you can't see or otherwise detect the problem now then this should at least work, if not as quickly.
I do have a new Sovtek gz34 orderedLast edited by Valvehead; 05-29-2020, 06:22 AM.
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Like Enzo said, measure the current through the fuse, both when running and during the power-up surge.
JTM style amp with a pair of KT66 should not require any more than 3A slow-blow fuse.Originally posted by EnzoI have a sign in my shop that says, "Never think up reasons not to check something."
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Originally posted by Valvehead View PostWould the rectifier tube have any play in this ? I dont have a spare here . B+ is 474v
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I do have a new Sovtek gz34 ordered
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There is a possibility that the person who installed the switch, reversed the OT primary leads on the switch, which might give rise to high current draw in pentode mode caused by oscillation. Oscillation in pentode mode is more likely than in triode mode because of more gain.- Own Opinions Only -
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Originally posted by g1 View PostLike Enzo said, measure the current through the fuse, both when running and during the power-up surge.
JTM style amp with a pair of KT66 should not require any more than 3A slow-blow fuse.
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