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Decware Grounding Scheme (Read 545 times)
hifitubes
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Decware Grounding Scheme
10/26/13 at 20:31:31
 
I've been troubleshooting why my dishwasher creates a buzz that comes up either AC + or the Ground into my Rachel amp.

It appears that all (4) speaker terminals and the - RCA short to the IEC ground, but not chassis. I have noticed if I tie the transformer to the chassis of my DAC, hum drops a bit. I probably also have DC on the line as both units chassis/tranny buzz and vibrate.

Is this normal? Or part of the Decware design e.g. floating transformer ground.

i've read this from a well-respected designer; not saying this is good or bad just curious as to design.

Quote:
You can sort out easily enough if the equipment is properly grounded by using a DVM. Connect one lead to the chassis and one to the center pin of the IEC connection or power cord. You should measure a short.

Then connect to the ground of the input and output connectors. You should not see a short- but some nominal resistance. I've seen a lot of power amps where input ground and chassis ground are the same thing. Such a unit will be sensitive to the earth ground. I've seen others where the chassis seems to float relative to the inputs. Again, there will be troubles with ground.
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« Last Edit: 10/26/13 at 20:33:12 by hifitubes »  
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hifitubes
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Re: Decware Grounding Scheme
Reply #1 - 10/27/13 at 17:44:07
 
So today I put a cheater plug on the Rachel, hooked it up to an AC regenerator, and turned on the dishwasher.

A loud buzz comes out of the speakers when dishwasher is running.

I measured 20V AC across chassis of DAC to + Rachel binding post, 30V AC across AC Regenerator chassis to + Rachel binding post, and 3v from chassis of Rachel to + Rachel binding post.

I wonder if neutral and ground are tied at dishwasher?
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hifitubes
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Re: Decware Grounding Scheme
Reply #2 - 10/27/13 at 18:35:08
 
Should the + and - speaker terminals short? Input jacks - shorts to both + and - binding posts.

I guess it must be by design, floating bridge...
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Mark
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Re: Decware Grounding Scheme
Reply #3 - 10/27/13 at 21:57:18
 
Question: Are you powering up your audio system from a sub-panel?...

Many sub-panels are wired wrong...  They should have the neutral floating, and not bonded to ground...  Bonding the neutral to ground should only happen at the main dist. panel...

Added: Note: If you do have a sub-panel, when you look at the neutral buss-bar, only white wires should go to it... And the bonding screw should be taken out...  All the bare copper grounding wires should go to a separate accessory bar that manufacturers sell for this purpose... (m.)
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« Last Edit: 10/27/13 at 22:08:04 by Mark »  

If a rabbit defined intelligence the way man does, then the most intelligent animal would be a rabbit, followed by the animal most willing to obey the commands of a rabbit. -Robert Brault, writer (b. 1938)
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hifitubes
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Re: Decware Grounding Scheme
Reply #4 - 10/28/13 at 05:45:03
 
Firstly, Steve said my amp checks out. I meant continuity, and since I'm a layman, a short was the wrong choice of word.

Mark, thanks for post. I will check today when electrician gets here. Something is not right.

My buddy has a studio on camp and says he has 3-phase, and a sub-panel. I don't think I do.
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