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Repair diagnosis for cdp with humming tranny

I have an older Raysonic CDP which has a humming transformer once the unit has heated up for an hour or so. I pulled the tubes, hooked it up to a a DAC, and it works perfectly (never hums) if you like the sound, :-(

I've had it into a local repair shop twice - they tried but didn't fix. Any techies out there who might have a thought?
newbee
Post removed 
nonoise's avatar
nonoise
11,226 posts
 
Just teach him the lyrics.
erik_squires
16,922 posts
 
Try it in another home. 

If it goes away, you have DC on your line. 

The cure for this is to eliminate the source (often digital power supplies, and dimmers) or to get a balanced power supply. 

Best,

E
imhififan's avatar
imhififan
2,238 posts
 
Over time, the transformer core adhesive starts to break apart, maybe some large heavy duty hose clamps could help.
https://www.qsl.net/kf8od/ccore11.jpg
https://www.qsl.net/kf8od/ccore7.jpg
newbee OP
4,824 posts
 
Thanks for the advice. Unfortunately nothing works, really. 

Elizabeth, FYI as you like using spinners and DAC's. I tried using the digital output of the Raysonic into the Marantz (SA11s3) input - didn't care for the sound at all. But, I acquired two other cheap DACs, the Cambridge and the Peachtree. The Cambridge was OK but it really worked better with some cheap spinners I have. The Peachtree was an improvement over the built in DAC in the Raysonic. Clear, clean, linear, and tonally spot on. Great synergy with my system. FWIW.
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