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.
4 posters
SP14 mechanical hum.
FearOfMusic- Posts : 21
Join date : 2019-01-07
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
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.
Roy Mottram- Admin
- Posts : 1839
Join date : 2008-11-30
maybe the rectifier is thinking of dying? Another replacement is cheap!
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
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.
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.
FearOfMusic- Posts : 21
Join date : 2019-01-07
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.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
Please See New Post (different subject).
FearOfMusic- Posts : 21
Join date : 2019-01-07
I’m not seeing a new post from you.
FearOfMusic- Posts : 21
Join date : 2019-01-07
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.