#1
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6V6 enigma
I've got a pair of 6V6's (P/P outputs) in a Zenith 10S669. They both test equally bad on my Heath TC-2 but they play fine and loud. Wondering if anyone else has encountered a puzzle like this, it could be an error in the settings chart of the tester? Every other tube in the set tests good. There are no problems with the set, but this has me confused?
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#2
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Weak output tubes will play, but not as loud and not that long... especially in a push-pull amp, where much of the distortion will cancel. But the tube tester data could be qestonable too - do similar tubes like 6F6, 6K6, 6L6 test OK? (6AQ5, 6CM6, 6CZ6 should have the same settings except for pin settings, 12AB5, 12V6, 12AQ5 also are the same but with heater set to 12V)
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#3
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Yes, other tubes of like kind test normally, some good some bad as they should be. Maybe the 6V6's are just on their last leg.
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#4
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If those 6V6's just read low on emissions and checked out ok otherwise, find/get a "known" good one to compare on your tube tester. Or, have someone else check it for you against theirs. It's not like you're using those tubes in a hard driving guitar amp and you may be surprized at how much life is really left in them. Being push-pull, as long as they test simular and being cathode biased you should be allright.
I'd run every bit of use out of them that you could. 6F6s' will often test weak and work great too, common with them. I have a tested weak/low on life 6F6G that I have in a daily player Philco and occasionally I'll re-check it and it's value stays the same and the radio sounds just as great! Original output tubes in these old Zeniths just seem to last too! |
#5
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I'm afraid lots of people throw away tubes that test weak without ever trying them out in a circuit.
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#6
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Hmm this gives me some encouragement, as I have a nice pair of GE 6v6G's with the cool art deco 30's lettering on them that test weak, but sound great in some of my guitar amps. I have 4 of them, the one good pair does service in my J-805 console.
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#7
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As far as radios, the best test for a tube is to see how it operates in the circuit that it will be used in. I normally don't replace tubes in a radio unless performance is not up to snuff. I've seen plenty of tubes that tested "weak" or "bad" on a tube tester; yet, still worked OK in a radio.
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#8
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This Zenith radio I have had the same issue. It played quite nice with a worn pair of 6V6's. At some time later they both equally got worse to the point in which the audio finally fizzled out out. So essentally the unit depleted the tubes kind of like draining a bathtub.
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Honey, turn on the tv.. I'm cold! |
#9
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I was the first to remove the back on my '62 Motorola stereo. I still haven't checked the tubes, none of them. I've been using it over a year. I did look at all the tubes and the date codes put them as original! ALL of them! I wonder what they test like? The amp uses 6 6V6's and the pre is 6AU6's. I'm still slowly poking around in there cleaning and checking things out, I just love the fact that Drexel veneered and stained the inside of the cabinet, it's almost a shame to put the back on it again. I'm still hemming and hawing about recapping it, I might just do the cans and any obvious crappy ones. I'd hate to change the way it sounds. I say use the 6V6's until they die, it's a waste to throw them out sooner IMO.
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