Shielded Ground Question

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surfsup
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Shielded Ground Question

Post by surfsup »

In the first picture in the series here:

http://chicagocadcam.com/ChrisHahn/amp.html

There is a shielded ground from the master volume pot (all the way top right pot), that the ground line I have coming from the front of the shrink. I am wondering, is this okay? Or should the ground line go the other way like the other shielded grounds?

I'm wondering if the ground line is too close to the soldered turret and causes interference.

Also, should the shielding cover as much of the line as possible? Or should I cut the shielding back from the inner wire quite a bit?
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jjman
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Re: Shielded Ground Question

Post by jjman »

It looks like the shields are connected to the ground buss which has pulsating current on it. The buss appears to be handling all the PS filter and cathode grounds. I would prefer to attached shield to grounds that don't have current pulsing thru them. If the pots are contacting the chassis (not isolated) their bodies would be grounds that don't have current on them. The body of the pot is the "shield" for the signal going thru the pot's internal circuitry.
If it says "Vintage" on it, -it isn't.
surfsup
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Re: Shielded Ground Question

Post by surfsup »

Yes the pots contact the chassis, so to be clear, you're saying it would be better to attach the shield to the pot body? What about a separate ground on a terminal ring with the other to terminal rings?
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Structo
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Re: Shielded Ground Question

Post by Structo »

I don't like to solder to the pot body for obvious reasons.

But generally in audio, you ground the shield of a signal cable at the source only.
If you ground both ends you are sure to cause a loop and hum.

Trim the braid back on the termination end and put a piece of heat shrink over the end to neaten it up.
Tom

Don't let that smoke out!
surfsup
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Re: Shielded Ground Question

Post by surfsup »

okay, only one side is grounded and I shrunk it, there's about 3/8 inch distance between the shielding and end of the wire. My question was this, though, in the two photos, I have one coming from the front, the other coming back along the lead. On the first one, is it okay to have the ground line come out the front like that which is near the turret for the live wire?

[img:496:372]http://chicagocadcam.com/ChrisHahn/shield1.jpg[/img]
[img:620:465]http://chicagocadcam.com/ChrisHahn/shield2.jpg[/img]
passfan
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Re: Shielded Ground Question

Post by passfan »

That red wire in that ground buss eye looks like a cold solder joint. You may want to wet that again.
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