[sdiy] "Zerolytics"

Michael Zacherl sdiy-mz01 at blauwurf.info
Wed May 6 17:54:40 CEST 2020

> On 06.05.2020, at 16:33, Tom Wiltshire <tom at electricdruid.net> wrote:
>> On 6 May 2020, at 14:40, Michael Zacherl <sdiy-mz01 at blauwurf.info> wrote:
>>> On 05.05.2020, at 15:24, Chromatest J. Pantsmaker <chromatest at azburners.org> wrote:
>>> At work we have many high-end powered studio monitors.  They're getting up there in age and they start to hum louder and louder.  
>>> Guess what fixes the problem?  
>>> New capacitors in the power supply.
>> I’m curious why that would work!? 
>> Sitting next to a modular synth with a Power-One linear PSU which gradually became louder and louder.
>> But I’m afraid that’s just the transformer. :/
> It *might* work because new caps would reduce mains ripple compared to old ones. Hopefully! Otherwise what’s the point?!

Well, sure, so there would be an emphasis on the second harmonic in that hum? ;)
Then again, I’m curious why that would cause (or not) a sound - would the current load on the transformer be that different?

> But I know what you mean. I’ve got an old toroidal transformer on the back of my desk running a test supply. You can tell by how loud it hums how much work it’s doing. Plugging in any circuit with a short on it produces a decently loud hum, and you know somethings up and to unplug it right away. It’s actually quite handy as a basic sanity check!

well, needs a good ear (which is part of our job, obviously) and a very quick hand! 

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