Bonsai shows his recommended wiring of a two channel amplifier. He has not shown a DC zero ohms connection between audio and enclosure.
I have been tinkering with a Sony CDP-591, it is class II, so no PE.
The 4 RCA barrels are made from a single piece of metal and bolted directly to the chassis. The circuit 0V/output ground has a very short connection from the edge of the board to the RCA's. What they have done is place small 100nF capacitors throughout the circuit connecting 0V/GND to the chassis.
The 4 RCA barrels are made from a single piece of metal and bolted directly to the chassis. The circuit 0V/output ground has a very short connection from the edge of the board to the RCA's. What they have done is place small 100nF capacitors throughout the circuit connecting 0V/GND to the chassis.
Then their ClassII (double insulated) construction is relying on the double insulation between all mains connected components never failing by sending Mains voltage to any isolated component/chassis.
That gives a clue to how onerous the Design, Manufacture, Test, and Guarantee is for a ClassII product. And how much more difficult that is to achieve in a metal chassis that is exposed to touch.
That gives a clue to how onerous the Design, Manufacture, Test, and Guarantee is for a ClassII product. And how much more difficult that is to achieve in a metal chassis that is exposed to touch.
Doesn't look too difficult to me. The transformer sits on the PCB and the mains fuse is hidden in the transformer. The mains cable is connected to the PCB with no switch.
Where DIY goes wrong is the long internal wiring. Connect the output to the chassis and design a short path to the power GND.
Where DIY goes wrong is the long internal wiring. Connect the output to the chassis and design a short path to the power GND.
1] AC power Protective Earth/Safety Ground should be permanently attached to the chassis near the AC power inlet.
2] All audio signal interconnect shields should be attached to the chassis at the connector.
3] Main Audio Ground (Audio Circuit Common) should be attached to the chassis near the input signal connectors.
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XLR balanced interconnects have no ground pin, pin#1 is the shield.
2] All audio signal interconnect shields should be attached to the chassis at the connector.
3] Main Audio Ground (Audio Circuit Common) should be attached to the chassis near the input signal connectors.
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XLR balanced interconnects have no ground pin, pin#1 is the shield.
Under those circumstances the Sony's chassis would only be coupled to Earth through the interconnects if the receiving equipment was DC coupled to Earth at signal return. Would it be better to directly couple the Sony's chassis to Earth if the signal returns were AC coupled to the chassis at the receiver?
I've just checked my Marantz CD6004, I have DC continuity between RCA ground and chassis
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I don't know! Isn't just to do with RF screening?
Besides the safety element of course
Besides the safety element of course
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Back to post 56. Rule 1 does not require an Earth connection, only that the shield must be connected to 0V/GND of the circuit. The shielding and 0V can be floating relative to planet Earth.
This I understand. What I'm having a problem with now is the following
When the chassis is used as shield for RF it needs to be connected to the Earth?
When the chassis is used as shield for RF it needs to be connected to the Earth?
My statement stand, many think of earth as the ultimate sink, hense these grounding boxes. Explain how we cater for RF interference on aircraft as I am doing now!!!
No earth is there for the PE connection that is really all it is for it is a safety feature, double insulated designs have no earth connection. As tsated in my last post aircraft have NO connection to earth, managed to get 18GHz RF immunity on some stuff for a trainer jet, vehicles have no earth connection in fact they are well isolated, get RF immunity for all the stuff we do to go in there, despite GPS and mobile phones everywhere.
Some reading matter...
One of my favorites...
http://sites.ieee.org/ctx-emcs/files/2010/09/Archambeault-Ground-Myth.pdf
some good links at the end of the article...
Planet Analog - Bruce Archambeault - The Ground Myth
One of my favorites...
http://sites.ieee.org/ctx-emcs/files/2010/09/Archambeault-Ground-Myth.pdf
some good links at the end of the article...
Planet Analog - Bruce Archambeault - The Ground Myth
As above, the Planet Earth has little to do with RF Interference.
Jim Brown the go-to EMI/RFI expert has done field experiments using portable power near a powerful radio transmitter. In some tests, a connection to Earth increased the interference.
Note that at some frequencies radio antennas do involve Earth.
Jim Brown the go-to EMI/RFI expert has done field experiments using portable power near a powerful radio transmitter. In some tests, a connection to Earth increased the interference.
Note that at some frequencies radio antennas do involve Earth.
This is a very clear article. Grounding and Shielding Audio Devices.
It also states that RF immunity can be increased by a low impedance connection to planet Earth. I get the impression though that this is easier said than done
It also states that RF immunity can be increased by a low impedance connection to planet Earth. I get the impression though that this is easier said than done
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