Dual Yamaha C-80 with Loudness Hum
- Thread starter Kane4040
- Start date
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Is there a dimmer switch in the same room ? Noise on both channels ?
Thanks for the recommendation. I was certain there was no ground loop because I had gone through all the typical culprits. However, I found one. The metal roof in the house was connected to a ground rod. Once disconnected the ground loop disappeared in one of the C-80s. Unfortunately it remains in the other unit. They have both journeyed to multiple locations now to confirm it is not a ground loop. Let me summarize the status of the two units to give you all the information I have.
1- both units were fully recapped, however, different brands were used.
2- multiple cold solder joints were touched up
3- on the unit with remains trouble the rca jacks were all replaced
4- all pots and switches were thoroughly cleaned (the volume/loudness in particular)
5- TR149 and 150 were removed, tested, new thermal paste and bolted to the board
- When testing the hum occurs both on the headphones or connected amp.
- The hum is lower when selecting the phono stage (100 ohms) as opposed to the other inputs
- Touching the volume/loudness control reduces the hum
I can provide a photo if it would help.
Photos of the installation and soldered connections.
Thank you. I will work on both.
I removed both screws and added solder to the pads underneath. No change.
Today I went ahead and removed the center strap underneath the boards and touched up the solder pads you mentioned. However, it made the sound worse which makes me believe you are on the right path. Where would you point me next?