Turntable grounding mystery

I'm not dead, but I haven't tried anything yet, as life has been too busy. Should I not try that?

 

Just avoid this

 

CAUTION: Do not earth ground the 2230 chassis. It could cause more harm than good.

Do you have any other front end sources connected to any line inputs of the Marantz? If so disconnects the ICs of those from the Marantz and then check for the hum. Make sure the ground wire from the TT is connected to the ground terminal on the Marantz 2230.

Does the TT have a 2 wire power plug or a 2wire with equipment ground plug? If it uses a 3 wire plug, for a test try a ground cheater on the plug to lift the equipment ground from the TT.

Do you have a multimeter? If so set it to ac volts auto or on a scale above 120V.

*Disconnect all ICs from the RCA line inputs as well as the TT RCA phono input jacks. Also disconnect the TT ground wire from the Marantz.

*turn on the Marantz 2230.

*Touch one test lead probe of the volt meter to the chassis of the Marantz 2230.
Insert the other test probe into the U shaped equipment ground hole of the wall power receptacle. Make sure the probes are making good contact. You will read an AC voltage. Note, and write down the voltage measurement.

*Next reverse the 2 wire plug in the wall outlet and repeat the above test procedure again. Note the voltage reading. The lower voltage reading of the two is the correct AC polarity orientation for the power feeding the primary winding of the power transformer of the 2230.

* Connect the RCA IC plugs and TT ground wire back to the phono jacks on the Marantz, check for hum.

Post back your results.

 

I'd take jea48's advice. The only thing I'd add is: if it was me, and I didn't have any other equipment connected to the amp, I'd be curious to see what happened if I connected a piece of equipment that had a functioning three-pin mains plug. That would give your system a ground connection that it might not otherwise be getting, without doing anything weird or risky with the mains.

Good luck!

 

I found this doing a search on the Net. It may be of help/interest.

http://www.jmargolin.com/marantz/marantz.htm

 

Hi jea48 checked out the link very interesting. The Marantz was built before houses were required to have equipment safety grounds it appears so there is no chassis ground to the mains from the amp. The ground stud is for the chassis to be grounded externally (maybe thru one of the pair of ICs, the phono inputs are are tsken to gnd thru the .01uf caps, (very low capacitance for the TT cart, but I see the 47k ohms for the correct resistance) any one using these amps found a need to up the capacitance fo some carts?
It appears that for a safety ground it would go from the amp to a ground rod? or some way to a separate ground at the outlet box? Using the TT ground wire makes the TT and amp ground have continunity but still floating unless carried thru the CD or tape players by the RCA's?

 

I still bet that it is to do with other electrics in the house

 

Hi alfajim,

Yes it was built back in the 1970s. As for an earthed equipment ground it doesn't need one. And like I said before connecting the chassis of the Marantz 2230 to the equipment ground of the main electrical service could do more harm than good.

The grounding/shielding for the DC electronics of the Marantz receiver is the metal chassis of the unit where B- is connected. In the world of the Marantz 2230 receiver that is ground.
The ground the tone arm, tone arm wiring, and what ever else of the TT that needs to be connected to the chassis ground of the Marantz 2230 receiver.
Not to be confused with Mother Earth ground.

I am not sure what the OPs problem is with his Marantz 2230. I have owned three Marantz receivers from the 1970s, a new 2265B, a used 2252B, and a used 2270. I never experience the hum problem the OP is having. I should also mention I never connected any associated equipment that used the electrical system safety equipment ground either.

Something else to consider, is the OP actually hearing a hum or could it be a low lever buzz?

Jim

 

Lots of stuff to digest here!
As electronics are not my forte I have had to read some of these posts multiple times just to make sense of them.

Anyway...
I certainly could be hearing a low level buzz vs a hum. Would that change things?

It's actually not that much of a nuisance as when the music is on I can't even hear it. It just seems WRONG to me that when I touch the tonearm I can very clearly hear the electricity. It will buzz when I touch it, and if I tap the tonearm again in a different spot sometimes the hum gets lower.

What really brought this to a head for me was when I switched out the amp and the table became dead quiet with no electrical issues at all.

And of course all other inputs except the phono are dead quiet as well.

I will certainly not be trying to use a wire to ground the receiver and I honestly won't be buying a multimeter etc either as the issue is more of a nuisance than a major headache - and I don't trust myself enough to go too deep into this issue.

I will however, be going through some of the other suggestions posted here and reporting back. I was really hoping this was something simple!

Thanks to all

 

If the Marantz's power cord plug is not polarized (one metal blade wider than the other), did you try reversing the power cord plug when you plug it into the AC outlet? Older equipment without polarized plugs sometimes have different amounts of hum depending on which way the plug is connected.

 

So amazingly after all of this time I finally solved the mystery today. What a relief!

Over the past 6 months I tried many of the suggestions in this thread, each time with no success. I decided to once again work on it again today and read through this thread for the millionth time.

The answer was annoyingly simple and contained in Charlie's thought.... The plug for the TURNTABLE was reversed. I never realized that it could be switched, only that the Marantz could be. Apparently when I switched out the receiver that time I must have plugged it in correctly.

Anyway, I wanted to post here to thank you all for your help and also to possibly help anyone with the same issue who stumbles upon this while searching the net!

Finally silent listening for me! Whew!!!

 

Hi Scott,

You don't have the problem anymore ?
Even when you touch the tonearm ?

I recently bought a Thorens TD 203 and got the same problem
I tried lot of things but finally sent it back to the seller as it was under warranty
The technician of the shop called me this morning and told me that he had a Thorens technician on phone who explained him that they were aware of this problem at Thorens
They have this problem on different models with metallic tonearm
In fact, the tonearm is not linked to the ground loop … Big conception mistake !
So I'm interested to know which model exactly you have and if you had made something else than reversing the plug to erase this problem

Thanks in advance,
Best regards,
John

 

Hi John,

No I don't really have an issue with it any more. As it was, if you touched the tonearm it was a very loud buzzing and there was always a buzz present. After reversing the plug the only buzz I get, and it is very slight is when touching the end of the tonearm closer to the counterweight - however this is minor and doesn't impact my listening.

I have a 166 mk II, but it has a fair amount of customization.

Good luck!

Scott