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    SP14 mechanical hum.

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    FearOfMusic

    Posts : 18
    Join date : 2019-01-07

    SP14 mechanical hum.  Empty SP14 mechanical hum.

    Post by FearOfMusic on Fri Feb 01, 2019 9:18 pm

    Recently my sp14 started making a humming sound. Not through the speakers but from inside the case. It seems to me like it’s coming from the rectifier or somewhere nearby. It was dead quiet until just recently. I’m wondering if the rectifier can mechanically hum if It has started to fail. Thanks In advance for any insight you may have.
    deepee99
    deepee99

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    Location : Wallace, Idaho

    SP14 mechanical hum.  Empty Re: SP14 mechanical hum.

    Post by deepee99 on Sat Feb 02, 2019 4:04 pm

    Normally the hum you describe would be coming from a transformer or choke. Has one shaken a bit loose? Consider re-tightening the mounting hardware. Doubt it's the tube.
    tubes4hifi
    tubes4hifi
    Admin

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    SP14 mechanical hum.  Empty Re: SP14 mechanical hum.

    Post by tubes4hifi on Sun Feb 03, 2019 10:09 pm

    maybe the rectifier is thinking of dying? Another replacement is cheap!
    Peter W.
    Peter W.

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    Join date : 2016-08-07
    Location : Melrose Park, PA

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    Post by Peter W. on Mon Feb 04, 2019 3:22 pm

    Why things Hum:

    Per DP - something has come loose. It is my experience that many individuals are not happy about making things really tight for fear of breaking something. Make things REALLY TIGHT, and see if that works.

    Per T4HF - as transformers load up, they will hum more. And if there is something working towards increasing the transformer load, that could do it. Could be a rectifier, could be one-or-more power-supply caps, or even (a) tube(s) starting to short internally.

    Per Peter W. - it forgot the words.

    I have been known to use a piece of 5/8" wooden dowel to press on various things to localize a mechanical hum.
    That is, after I have eliminated any form of electrical problem or short.
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    FearOfMusic

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    Post by FearOfMusic on Mon Feb 04, 2019 3:45 pm

    Thanks for the reply's. I do not think that its the transformer. It's tight and the sound seems to emanate from the middle of the case. I'm gong to order a new rectifier to make sure it's not the issue. They are cheap and I would like having a back up anyway. Peter's dowel advice is really good. I was poking around trying to do see if anything was vibrating but with out the dowel. I got a big shock when I touched the heatsink on the TIP50 located at Q1. I knew better but wasn't thinking. 300V or so is a great way to remind yourself to work more safely next time.
    Peter W.
    Peter W.

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    Location : Melrose Park, PA

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    Post by Peter W. on Mon Feb 04, 2019 4:10 pm

    Please See New Post (different subject).
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    FearOfMusic

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    SP14 mechanical hum.  Empty Re: SP14 mechanical hum.

    Post by FearOfMusic on Mon Feb 04, 2019 4:21 pm

    I’m not seeing a new post from you.
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    FearOfMusic

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    SP14 mechanical hum.  Empty Re: SP14 mechanical hum.

    Post by FearOfMusic on Mon Feb 04, 2019 4:34 pm

    I see it now. Like I said I knew better. It was just a moment of momentary stupidity. Which are famous last words. I appreciate your post trying to keep us all safe. I actually own an isolation transformer that’s not in use. I like your recommendation to use it as a safety gap. Thanks.

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