ground issue

[GAbRT]

Hello,

Here is a new headache...

I am using a Marantz 2270 plugged into a Thorens TD 160.

As soon as I connect the ground into the Amp. the turntable slows down...

Any ideas?

Thanks

GAb

 

[Lux Man]

Wow! If I were sarcastic I would say, congratulations! That one deserves some kind of award.
I'm sure someone else will chime in with something more intelligent but the only thing that comes to mind is that the TT has developed some serious leakage so when the ground is grounded it is producing a minor short thru the motor. If you have a meter able to read current I would put it series with the ground wire and then connect the meter to ground and see what your leakage is.

I'll be interested to see the resolution of this one.

 

[REDone]

What mark on the TT ?

The TD160 Mk1 didn't have a ground

 

[JonL]

I'd take a wild ass guess based on my TD125. (I have no idea if the 160 has a remotely similar motor control circuit). On the 125 the motor speed is controlled by a circuit board that synthesizes different frequencies/voltages for the three speeds. With a two prong power cord, the circuit board ground would be floating and not tied to the mains ground. When you use the ground wire to the receiver the circuit board ground may now reference mains ground. Perhaps one of the electrolytic capacitors in the motor speed control is leaking. When the ground was isolated the leakage didn't matter. With the ground connected it's dropping voltage to the mains ground.

Plausible? I don't know!

 

[GAbRT]

Correction

Here is the follow up...

Actually the Thorens is not giving me any problems. The problem is when I plug in my Pioneer PL 61 turntable. (Sorry for the confusion.)

I just came back from my electronic store. They check for any leakage and couldn't find any. They said that Marantz and the Pioneer are probably not compatible as far as ground is concerned.

Is that possible?

 

[Lux Man]

Are you saying the Pioneer slows down?

 

[GAbRT]

Yes,

the rotation becomes unstable. it sounds like it's drunk.

I guess it slows down and speeds up.

 

[JonL]

Does it hum if you leave the ground wire off? There's no law that it has to be hooked up. If it doesn't hum, leave it off.

Did you try reversing the polarity of the AC power plug? If it's a non-polarized two-prong plug, try flipping it in the outlet.

 

[GAbRT]

it hums a lot...

i've tried to flip the plug and also tried to ground the tt everywhere but no success...

 

[JonL]

I'm out of ideas. Hopefully someone with more expertise than myself will chime in with suggestions.

Good luck....

 

[GAbRT]

really appreciated your help!

 

[Lux Man]

I am curious- how did the store check for leakage? As far as I know that ground should only be connected to the chassis and or the signal grounds, if it has and effect on the motor speed, there is obviously more going on here.

 

[GAbRT]

no idea,

unfortunately i have no knowledge in that field...

he mentioned something about some high-end equipment not being compatible with lower-end ones (is pioneer pl 61 lower-end?).

tomorrow i'll call somebody else and see what they have to say...