Hi All!
I have an audio main board, and an external potentiometer attached to the chassis front panel, regarding the wiring, i want to shield both the input and the output wires, but also want to avoid crosstalk, so i use single shielded cable for the wiring.( one for the input and another for the output.
The shield of the input signal is connected to the board gnd. But the shield of the output is not connected to board gnd. I want to make sure this is right or ok. Any comment is wellcome!!
attached is the picture/schematic of the wiring.
Thank you for your help!
JayX
I have an audio main board, and an external potentiometer attached to the chassis front panel, regarding the wiring, i want to shield both the input and the output wires, but also want to avoid crosstalk, so i use single shielded cable for the wiring.( one for the input and another for the output.
The shield of the input signal is connected to the board gnd. But the shield of the output is not connected to board gnd. I want to make sure this is right or ok. Any comment is wellcome!!
attached is the picture/schematic of the wiring.
Thank you for your help!
JayX
Attachments
Hi Rayma!
Yes, the fader amplifier is on the main board. The potentiometer is external to the main board. And everything is inside a metal box. There are wires from the pot to the main board. ( a 3 pin molex connector)
jay x
Yes, the fader amplifier is on the main board. The potentiometer is external to the main board. And everything is inside a metal box. There are wires from the pot to the main board. ( a 3 pin molex connector)
jay x
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This should be ok, although sometimes you have to experiment with the grounding, when adding parts
to an existing board. Maybe a close photo would be helpful.
I don't like breaking the two wire circuits between modules.
You have a two wire connection from input molex to vol pot.
You have only one wire and a very separated return route from the vol pot back to the PCB. This creates a BIG LOOP in the vol pot output.
That is bad.
Have a good look at the molex and it's connections. Is there a way to get the vol pot output to maintain a two wire connection into the next stage without using that grounding point?
Back to the input.
You show one wire as the input from the previous stage. That should be a two wire connection. Where is the other half of the two wire connection.
Don't say it doesn't exist.
It does, or the connection will not work !
You have a two wire connection from input molex to vol pot.
You have only one wire and a very separated return route from the vol pot back to the PCB. This creates a BIG LOOP in the vol pot output.
That is bad.
Have a good look at the molex and it's connections. Is there a way to get the vol pot output to maintain a two wire connection into the next stage without using that grounding point?
Back to the input.
You show one wire as the input from the previous stage. That should be a two wire connection. Where is the other half of the two wire connection.
Don't say it doesn't exist.
It does, or the connection will not work !
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There isn't a perfect way to wire an off-board pot to a board with one ground at that point in the circuit. You have to choose between a ground loop, or separating signal and return for one of the legs.
You can make the ground loop as small as possible by keeping the cables closely together (and maybe even twisting them) though. The 3-pin Molex may have been intended to be used with something as simple as a 3-conductor ribbon cable, and that's what you want to emulate.
Hi Andrew!,everybody!
I appreciate your comments, and will take a look to improve this!!
Andrew, the one wire as the input from the previous stage is a trace on the main pcb. I use ground plane on bottom layer, gnd fill on top.
hmmm, as a fast thinking...maybe extending an isolated trace from the gnd of the opamp output...without thermal pad... i could connect this gnd to the wire... hmmm... have to mash/cook these ideas....🙂.....
jay x
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