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Topic: Bad rectifier tube? |
David Nugent
From:
Gum Spring, Va.
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Posted 4 Mar 2016 1:39 pm |
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| Was curious on what the symptons of a bad rectifier tube are? The unit in my amp seems to glow very brightly, even on standby. When amp is switched to on from standby, it makes a loud buzzing tone and if not switched off immediately will blow the fuse.. |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 4 Mar 2016 2:18 pm
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Dave,
Not sure what amp you have or tube type. In the case of a 5U4, the high voltage is usually taken off of either filament connection. . . pin 2 or 8.
If you can break the line going from the rectifier to the filter capacitors and choke, the rectifier plates will probably not glow when it is powered up. If this is the case, it would indicate a short somewhere in the B+ line. First thing I'd suspect would be a shorted filter cap. Be careful, High Voltage.
Craig
_________________
"Make America Great Again". . . The Only Country With Dream After Its Name. |
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Mike Wheeler
From:
Delaware, Ohio, USA
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Posted 4 Mar 2016 2:36 pm
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Yes, shorted filter cap. I would advise replacing all the power supply caps. When the rectifier tube goes bad, it usually just self-destructs...but it can be damaged from a shorted cap, so I think I'd replace it also...just to be safe.
_________________
Best regards,
Mike |
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David Nugent
From:
Gum Spring, Va.
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Posted 4 Mar 2016 5:21 pm
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| Gentlemen, thank you so much for the helpful replies. It appears that this is a problem beyond my limited knowledge of electronics, therefore will be seeking professional help...Thanks again! |
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Len Amaral
From:
Rehoboth,MA 02769
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Posted 4 Mar 2016 6:00 pm
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| Dave, you could just have a bad rectifier tube. If you replaced it and put the amp on standby and watch the tube to see if it glows like the one you had? |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 4 Mar 2016 6:31 pm
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Gentlemen,
I offer another one of my unproven theories regarding tubes or transistors:
If it's open, it won't get hot because no current can be drawn. If it's shorted it won't get hot either, but something "upstream" will. Usually the fuse. If the circuit is not fused, then the transformer will overheat, or a circuit breaker in the house might trip. Other than shorted turns in a transformer, if a component is getting hot, it's usually caused by another component being faulty.
Dave,
What kind of amp is it?
Craig
_________________
"Make America Great Again". . . The Only Country With Dream After Its Name. |
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David Nugent
From:
Gum Spring, Va.
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Posted 4 Mar 2016 7:18 pm
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| Craig..It is essentially an early tweed Fender 'Super'(non reverb) design built from a Mojotone kit. I reconfigured it from a 2x10" to a 1x12". It worked perfectly when last used, so this problem has developed rather suddenly. The rectifier tube glows very brightly (as stated, even when on standby) and becomes very, very warm to the touch, much more so than the 6L6 power tubes. When the amp is turned to the on position, the rectifier tube glows suddenly much brighter and the unit emits what I can only describe as a pronounced "honking" noise much like the speaker is being overdriven. |
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David Mason
From:
Cambridge, MD, USA
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Posted 5 Mar 2016 6:29 am
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| It's goinked. Seek help. |
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David Nugent
From:
Gum Spring, Va.
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Posted 5 Mar 2016 12:28 pm
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| David..I am seeking help, that is the purpose of this post! |
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Ken Fox
From:
Nashville GA USA
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Posted 5 Mar 2016 3:09 pm
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Hi Dave,
I have seen a lot of the Chinese rectifier tubes that glow very orange. As this is newer amp I would first suspect a power tube. Pull both out and see if the amps stays on and does not blow a fuse. Without the amp on a bench it would be hard to trouble shoot, but at least that is one test you can try. |
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