Excellent work, I was just going crazy with the buzzing that afflicts my Sansui Au717 concentrating on the filters but now maybe you have directed me on the right path. Thank you very much
While filter caps are often the cause of humming or buzzing they are not the only cause. It's one of those issues that using an oscilloscope will help to diagnose. Carefully probe each of the regulated supplies and you may well find the issue. Happy hunting!
I totally agree. Check everything first for problems. Not all the owners are able to identify/notice possible malfunctions. Certain faults, moreover, are only visible with the appropriate instrumentation. In your case, hum presence could have induced to point the finger to bad capacitors. As you well showed there was a more serious problem. Great job so far!
You're so right about test equipment showing issues that wouldn't be seen/heard. High frequency oscillation is a prime example. That distortion analyzer I have has shown me problems I never knew I had.
i did not know that a shorted transistor in the power supply could create hum until i found one in my nad 2140. that thing had several bad caps, 'lytics and ceramics causing hum and each bad one that i found reduced the hum enough to find the next failed part. once i got it under control, i replaced every cap regardless of the type. that amp is now about the quietest amp that i have. :) thanks for the video ray👍
Yeah, it was a revelation the first time I saw it. I guess amplifiers are more than just a collection of capacitors, as some seem to believe. Who knew? 😝
Tips = Re: Bending cap pin = Research wire bending tools that are used to make jewelry. You do not need a precision set. Hobby Lobby is a good/cheap source. "Loop" pliers are particularly good for bending pins, without putting any pressure on the component, itself. No more cracked ceramic dip caps, at the pin/ceramic junction. I also use my flat bill pliers very often, to straighten pins, or to make bends. When I was a sound tech in the 70's, we trained our ears to readily identify the Hertz of a tone. This made it easy to identify feedback and to pull it out with an equalizer. Just giving back to the Community that likes giving back to the Community, as you say. grin.
I'll have to look into those tools. Thanks for the tip! I used to play guitar in bar bands. Used to work with a singer who had the bad habit of holding his mic down by his side when not singing/talking. Right by the stage monitor. He could never figure out why we had such bad feedback issues. I ended up patching a Behringer Feedback Destroyer into his mic insert. I'd have to reset the filters when we took a break, they all be active!
@@raysmith8307 Ray, send me an email from my About page, and I will give you contact information on a gentleman in Hertfordshire who specializes in Sansui.
