Yamaha YP-D71: hum when motor kicks in

[wgbeatty]

Hello-
I have a YP-D71 table with a Denon DL-301II cart installed. Sounds great, although I'd love to assistance figuring out the source of the hum. No hum when table motor is not running, as soon as I select Play, the hum kicks in. Hum does not increase nor decrease if I touch the head shell or tone arm. I have it grounded to my phono pre (Pro-ject Phono Box S) and have also tried grounding to the earth ground wire I wired to copper plumbing in our home as well as directly to the Yamaha integrated I use. The hum does not get louder as the tone arm/cart moves toward the center either.

I'm using new wiring in the head shell and have also cleaned the gold contacts on the head shell and inside the tone arm where the shell plugs in.

I've read there is a at least one ground wire to the motor inside. Perhaps worth looking inside at the wiring?

Warren

 

[avionic]

Did you try flipping your AC plug on the TT 180 degrees.

 

[wgbeatty]

Yes, tried that as well - although I did not mention it.

 

[dksp]

Strange.
Before opening the turntable, do you have another turntable to try out? Or another cartridge?
Are the leads installed correctly? Maybe you could try cleaning the SME headshell connectors.

I have the same turntable with the DL-103 cart and no hum at all.

 

[dksp]

There is a grounding wire:

 

[wgbeatty]

Ended up looking inside and didn't see anything out of the ordinary. Ground wires all there and connected. The hum is still there with all I've tried.

 

[Electone]

I have a YP-66 which has the same issue. It's not audible during playback, but it's definitely there before the needle hits the vinyl.

 

[Balifly]

Ended up looking inside and didn't see anything out of the ordinary. Ground wires all there and connected. The hum is still there with all I've tried.

There is a micro switch mentioned in the service manual, check and make sure it is fully functional.

Also check the tone am muting switch ( if there is one used).