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Author Topic: Grounding techniques  (Read 32239 times)

joecool85

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Re: Grounding techniques
« Reply #15 on: October 10, 2012, 12:25:27 PM »

Should we worry about star grounding in some line-level audio equipment that doesn't produce high output currents?  Like some equalizer box or preamp or whatever.  Say it's made up half a dozen dual op-amp chips, all dual-supply, which are mostly at unity gain or very modest gain.  It's convenient to just run a single ground trace reaching all the places on the board which need a ground.

If you build it and there isn't any problems you are good and if it's noisy, then you'll want to try star grounding.  Unfortunately that is the only real answer.
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henry909

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Re: Grounding techniques
« Reply #16 on: October 12, 2012, 01:21:09 AM »

I came to this forum looking for info to help solve a grounding problem with an old amp. And here the first thread I find is about grounding. But I am not sure whether I understand enough of the discussion above to figure out how to solve my problem.

Problem: I have an old Kay Model 780 SS amp. It has an old style two prong power cable, i.e., it doesn't have the third ground prong. The amp produces a lot of static and when you touch metal on the guitar , eg., the whammy bar or the bridge, you can hear static clicking through the amp. I suspect that the problem is the lack of ground on the power cable which goes through a grommetted hole in the chassis.

Can anyone give me an explanation of of how to add a ground to the power cable to see if that eliminates or reduces the static? Can I remove the chassis disconnect the old power cable. Then connect the two non-ground wires where the original power cable was connected and then simply screw the ground wire to the chassis?  Thanks.
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DrGonz78

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Re: Grounding techniques
« Reply #17 on: October 12, 2012, 08:59:00 AM »

Take out your DMM and make sure what color wire is hot and neutral through the power cable. Then remove the cable and get a 3 prong type power cable. (Assuming you are in the US) Basically, you have answered the solution all ready in your post. Drill a hole in the chassis and attach a ground wire. It is really easy as you said in your post. Sometimes I find Black hot and other times white is hot...? Look at the function of the power cord in relation to your DMM. Adding a ground wire should solve your problem.

P.S. - Star grounding is something totally more advanced in my thinking in relation to just adding a simple ground wire.
« Last Edit: October 12, 2012, 09:02:46 AM by DrGonz78 »
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joecool85

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Re: Grounding techniques
« Reply #18 on: October 12, 2012, 12:54:43 PM »

P.S. - Star grounding is something totally more advanced in my thinking in relation to just adding a simple ground wire.

Star grounding is normally used for audio signals, not power chain.
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