Hum issue with U-Turn Orbit

[62sunbeam]

My brother bought a new Orbit with acrylic platter and OM-5 cart. He says that after listening for a while a hum builds to the point of becoming annoying. He says unplugging the RCA plugs from the phono input of his Yamaha HTR and plugs them back in the hum is gone.

U-Turn says it's something with his equipment but I figure it's a grounding issue.

Ideas?

Thanks

Eric

 

[stereofisher]

RCA cables? Long shot as its new. Have seen it though. Had two yesterday

Eric

 

[NoTransistors]

Eric,

I tried to reach you concerning tomorrow. Maybe you will get back to AK tonight, and see this. I left a note in 'Conversations', or just call me.

 

[beatcomber]

The first thing I would do is replace the cables.

 

[Dave3009]

I know this is an old thread but for the record. Just received my Orbit Custom (acrylic platter, Ortofon Blue, Walnut Plinth). I have never had turntable hum before even with a Sumiko MC cartridge with a NAD receiver. Plugged in the the Orbit and WOW - hum and buzz. Cable changing made no difference. Orbit's have no dedicated ground wire, but the table components are connected to the left output RCA shield. The NAD has a 2 prong power cord and is therefor not grounded. I've never had an issue with that. My first experiment was to touch Orbit's tone arm with a grounded wire. Hum and buzz gone!. Not a practical solution, so I connected the wire to the unused ground post on the NAD. Same effect - hum gone. A quick conversation with Ben at U-turn confirmed the left shield grounding. Since the Orbit, and many other tables today are powered by un-grounded wall warts, there was no actual ground in the system.
Evidently the Orbit is sensitive to what the Ham community calls a good earth ground. They can provide adaptor for the table output that provides a pig tale to either an outlet ground slot or the ground post of a preamp or receiver if that is grounded.

BTW so far very happy with the orbit. Quiet, speed right on and no audible flutter. More importantly so far i like the musicality, enjoying some albums I was unimpressed with in the past. In the long run, that's the goal. Suddenly there are a lot of choices in the $400-$600 range.

 

[Lavane]

I know this is an old thread but for the record. Just received my Orbit Custom (acrylic platter, Ortofon Blue, Walnut Plinth). I have never had turntable hum before even with a Sumiko MC cartridge with a NAD receiver. Plugged in the the Orbit and WOW - hum and buzz. Cable changing made no difference. Orbit's have no dedicated ground wire, but the table components are connected to the left output RCA shield. The NAD has a 2 prong power cord and is therefor not grounded. I've never had an issue with that. My first experiment was to touch Orbit's tone arm with a grounded wire. Hum and buzz gone!. Not a practical solution, so I connected the wire to the unused ground post on the NAD. Same effect - hum gone. A quick conversation with Ben at U-turn confirmed the left shield grounding. Since the Orbit, and many other tables today are powered by un-grounded wall warts, there was no actual ground in the system.
Evidently the Orbit is sensitive to what the Ham community calls a good earth ground. They can provide adaptor for the table output that provides a pig tale to either an outlet ground slot or the ground post of a preamp or receiver if that is grounded.

BTW so far very happy with the orbit. Quiet, speed right on and no audible flutter. More importantly so far i like the musicality, enjoying some albums I was unimpressed with in the past. In the long run, that's the goal. Suddenly there are a lot of choices in the $400-$600 range.

I use one as a second table. I didn't run into this issue, but I did see a mod done that grounds the base of the tone arm from the underside. Also there is a jumper on the small circuit board that was bridged to help eliminate hum. I lost the link though. It's good they offer the adapter now. Obviously they had enough complaints to warrant it.

 

[cadillacmike]

Interesting. I wonder if I should run a wire from my Harman Karden's ground post to the ground screw of the wall outlet, since neither the receiver or the TT has a 3 prong plug.

 

[Dave3009]

It won't hurt, but unless you have a hum problem its not strictly needed. In equipment with two prong plugs, on conductor is the hot and the other the neutral. The neutral is connected in your fuse/circuit breaker panel to ground. The difference is that current flows in the neutral, but current is not supposed to flow in the ground unless there is some kind of failure, hence the purpose of "GFI's" ground fault interuptors. Most two prong plugged equipment is "floating" relative to the chassis. That's because is you managed to plug the plug in the wrong way and the neutral was connected to chassis, you would get a nasty shock when you touched it. Used to happen all the time in the "old" days.

So, in almost all equipment with 2 prong plugs (including my NAD receiver) unless you intentionally connect your chassis ground screw to the center screw of the wall outlet or the ground prong hole, your chassis is floating. Connecting other equipment to the chassis ground screw will simply connect the two chassis' together electrically. I'm an electrical engineer and I missed this originally connecting the Orbit.

 

[cadillacmike]

Most of my stuff is old enough to not even have polarized plugs (one tab wider than the other), let alone grounded plugs. The Dual has the polarized plug but I filed the wider tab so it would fit into the HK receiver's outlets in the back. I can still tell which one TT plug tab was wider. The HK does not have a polarized plug. Neither does the old Pioneer reverb amp nor the JVC tape deck. I never thought it made a big deal.
I could plug the Dual into an outlet where I can make sure it's correctly polarized and also ground the receiver to the wall outlet. But I never had a real problem with hum before with the TT plugged into the receiver.