RCA Grounding help

tazzo

Member
2012-03-22 1:13 am
Having some problems grounding my RCA connectors.

I have grounded it as follows;

4 RCA connectors with insulating washers and 4 grounding tabs.

The thick red wire in the picture passes through all four tabs and is connected finally to the RCA connector on the far right as a chassis ground. (has no insulating washer).

The two thinner red wires are connected to this thick red wire between each input and output red and black RCA connectors and then finally to each of the two grounds on the PCB.

Problem - very garbled sound from right channel at high volume and none from the left. I'm sure this is the right way to ground the RCA connectors.

Funnily enough, if I dismantle the grounds connections, and leave one ground wire attached to the PCB ground and let it touch the red RCA input connector hot wire, I get good sound, but it is not how it is supposed to sound.

Earth ground is just below the RCA ground on the far right hand side RCA connector.

Need help;

Thanks
 

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The SIGNAL from ONE RCA is a two wire connection.
Those TWO wires must remain close coupled from RCA to the TWO signal pads on the receiver.
They should not have taken ONE signal wire to chassis along a different route and then taken that along another different route to eventually complete the Signal Circuit.

Every one of those RCA sockets NEEDS a two wire connection to the next stage. None of those two wire connections should be broken.
You can use coax for the two wire connection, where the core of the coax is the RCA pin to receiver hot pad and the shield/screen is the RCA barrel to Receiver signal ground pad.
or
you can use a twisted pair to carry the two signal halves from RCA to receiver.

Before you modify this you need to find WHY they connected all the signal return wires to the chassis.
Is this the sole chassis to main audio ground connection?
If it is then this is there to comply with:
all exposed conductive parts should be connected to the PE protected chassis.

You will have to comply with this after you modify the input wiring.
 
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As a general rule phono connectors (what the rest of the world calls RCA) should be isolated from chassis. There is no point using isolated sockets and then connecting them straight to the chassis nearby! An isolated socket (plus the associated plug) is electrically simply a connection in the middle of the incoming signal cable, while being mechanically held in place by the chassis.

There usually should be a connection somewhere from signal ground to the chassis. The chassis must be connected to the incoming mains ground. The connection from signal ground to chassis could be from the circuit board or from the output - that is a design issue. You could use isolated input phono sockets and non isolated output phono sockets, but then you would not put a connection at the sockets from the input ground to the output ground as that would create a ground loop.
 

tazzo

Member
2012-03-22 1:13 am
I have used the two wire connection in every stage. Below is where I copied the grounding technique from where it shows it in more detail, but it still wont work.

Bozure.com - Rotary DJ-Mixers and DJ-Gear

The only difference from my technique and the one on the page above is, I ground straight to the chassis from the RCA ground tabs, however on the page above, it grounds to the PCB from the RCA tabs then to the chassis.

Still confused as it should be working with this basic configuration.
 
Yes, follow Andrew's advice and keep the return conductor near the signal conductor. Coax or twisting are options, although I prefer coax. Connect the case/chassis to the incoming mains earth - this is safety ground. In most cases it is helpful to have a connection between signal ground and safety ground, but the best place to do this varies with the circuit; it is a design issue, not a 'recipe' issue.