Phono circuit of Rotel RA931

[ALPUY]

Hi. I have built many phono preamp kits. All very good.
But none presents the ground connection of the rca with capacitor to ground of the circuit.
What benefit does this way of doing ?.
Greetings.

 

[rayma]

But none presents the ground connection of the rca with capacitor to ground of the circuit.
What benefit does this way of doing ?

A capacitor connected from the phono ground shell to chassis ground helps to suppress
radio frequency interference by shunting to chassis ground any RF picked up by the
phono cable's shield. It should have very short leads to be effective.

 

[ALPUY]

I do not handle English very well. But what I see the ground connection of the RCA is to the circuit ground.
The turntable land is directly on the ground of the circuit.
From what I interpret, the ground of the phono wire is not in continuity with the turntable land nor with the earth of the circuit. The capacitor is 0.1 uF.

 

[rayma]

From what I interpret, the ground of the phono wire is not in continuity with the
turntable land nor with the earth of the circuit. The capacitor is 0.1 uF.

In this case the filter is not so well implemented, but that is the purpose.

 

[ALPUY]

Okay. I will do the test with my Phono DIY circuits.
Thank you.

 

[rayma]

Okay. I will do the test with my Phono DIY circuits.

Use a small ceramic capacitor of around 0.01uF, and a solder lug attached to the chassis
right next to the jack. Trim the leads so the capacitor just reaches between the RCA shell
and the ground lug.

 

[ALPUY]

Thanks Rayma