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Looking for audio power supply expertise

ronnewman
Sat, 09 Jul 2016 16:44:27 GMT

Sorry, I didn't get the name of the fellow at Thursday night's meeting who has experience in audio gear, but this is also for everyone: does anyone have experience in noise-proofing a power supply? I have a rack-mount Kurzweil K2500RS synthesizer on eBay and just discovered it has a noisy output, and looking for someone to help me replace capacitors in the power supply or whatever is needed. Willing to pay. Symptoms: some hum, but not much, but a high whine in the outputs that have effects applied to them, and the whine increases whenever a front panel button is pressed.

Michael Schippling
Wed, 20 Jul 2016 18:19:33 GMT

Since no one has opined yet... Hum could be a power supply issue, or ground loop behavior in the connection to external equipment. Do you get it using just headphones attached to the instrument? The whine is curious, what front panel buttons effect it? If West Cooper shows up at the KIN Group, he has experience with rebuilding way old electronics and might take a stab at your way new one. Or I can poke at the thing sometime.

ronnewman
Wed, 20 Jul 2016 19:10:28 GMT

Hum was minimal, and with unbalanced cords out, so not worried there. But whine appeared in both headphones and effects output (not the dry outputs), and increased with every button pushed (which led to the hypothesis that it's power related, assuming a button increases power drain). Though no whine in dry outputs would indicate otherwise. All that being said, I sold the unit as-is, shipped it out Monday. Tnx anyway.