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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
imhififan's avatar
imhififan
2,191 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
4,767 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.
mcintech
128 posts
 
Newbee,

I would lift the PC boards the transformer is attached to (INPUT and OUTPUT) and check ALL solder joints, but especially under capacitors and rectifiers and under wire connections. Chinese made gear often exhibits poor solder, especially in higher current areas like power supplies and power amp outputs.
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