TT Hummmm Problem

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gene_stl

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It could be a filter cap on that USB and preamp board. Downstream from the yellow power wire. I would look into that before I tried to replace the cables which on a TT like that is likely to end in the trash can after throwing it hard against a wall. Don't ask how I know.
 

par4ken

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Thanks Ken. I can't say I'm so much of a fan of Japanese turntables but I am even less of a fan of belt drive units. The belts wear out. I figure I would have the same luck with replacing as I always have had with R2R belts: By the time I need a new one they are at least very hard to find, maybe impossible.

Having said that one of my favorite TT's from my past was the humble belt drive Phillips 212:

View attachment 78742

The only tone arm adjustment it had was tracking weight & anti-skate, but it competed favorably with the ubiquitous Acoustic Research table of its day. And groovy green touch sensitive switches!
They were hard to find but not now with eBay! I fixed my Connoisseur a year or two ago, it had been without a belt for maybe 25 years. Also a guy in England makes replacement motor suspension kits for it all found on eBay. More recently I replaced the belt on my Ariston Audio Turntable as well.

Years ago I got my belts mainly from MCM, you measured with your belt gauge and simply ordered the closest size. Sadly the were bought up by Newark and most of the old line was discontinued.
 
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MidiMagic

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I just remembered another "mysterious" phono hum.

The pickup cartridge was picking up the sweep frequency magnetic field from a CRT TV set next to the turntable. Moving the turntable solved the problem.

.
 

Sonik Wiz

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Randomly to @gene_stl :
There is no USB in the TT. Just an RIAA pre-amp. I would have replaced obvious filter caps but they are glued to the PCB's and I would have to remove the motor drive board (with the motor mounted to it) as well the motor control board that is foil side up with the filter cap on the other side. Too much risk vs benefit. And the power XFMR is shock mounted to eliminate hum vibes in the chassis. The metal tabs from the XFMR slide into some grooves in rubber vibration pads and those squeeze into plastic tabs.

So.

I removed power to the pre-amp board and I removed any phono cart connections too it. Then I soldered the RCA output flying leads directly to the phono cart wiring. A nice, typical straight forward phono cart > output connection. When I gave it a try the hum was worse than ever! A bunch so! Now I did removed my add on ground wire which I might put back & see if that helps with this altered wiring. So far I have discovered several ways to make the hummm worse, but not better. I am getting pretty good & opening up & re-assembling this table pronto. I know it's a quality unit because every time I do so have have another screw or 2 left over.

But I found this article informative. Which is why I might put the extra ground wire back in:

 

gene_stl

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Well since you excised the part the problem wasn't there. :LOL:
This is one of the problems, that you find the solution , the last place you look.
you need a four position terminal strip with a shield cover. Prolly have to make it.

I also know that if anyone can beat this into submission it is Sonik Wiz.

Good Luck!





Some audiophiles might freak out at using WAGOs but they are great and are UL approved for very high currents with no time limit.
 
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Sonik Wiz

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OhBabyOhBabyOhBaby! Success!
After doing what I did in my most previous post I re-hooked my add on ground wire inside the TT. And connecting to either the pre-amp ground screw or earth ground I get silence. Like a black hole. It's so quiet I had to check a couple of times to make sure I had the right buttons pushed & amps turned on.

Ya hear that @par4ken ? Back in action.
 

Sonik Wiz

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Ever notice how ya find things , the last place ya look???? :LOL: :LOL: :rolleyes:
Many yearz ago in the halcyon days of MCS Review, a few people suggested I start my own quad repair/upgrade "company", a la Quad Bob or QRX Rerstore (that wasn't even a thing back then).. I was flattered but decided not to. One of the reasons is I like DIY much more than repair. I mean, ya got a bunch of components in front of you just in from Mouser or DigiKey. You can probably assume they work as intended. And a schematic for a project if followed will probably work as intended. But something that is broken or problematic? It's a mystery, an unknown. Set up shop in the Scoobey Doo Mystery Machine.
 
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