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bikerhifinut · 20th Oct 2020, 3:27 pm

Quick question. I'm returning these 405 monoblocs back to stereo whilst the boards of one amp are in drydock.
So when I reinstall a new input socket, I am assuming that because I will be fitting a pair of Phono RCA sockets that I need to take a ground return from these to the star earth by the Bridge rectifier. The 4pin din socket soldered on the original mono input board has its chassis earth connected across signal earth and as far as I can see this one tiny nut and bolt is the only earth return for the whole amp board. i.e down the input screens. I wouldn't have thought this was very good practice, not least because it relies on a mechanical return to chassis for all the circuitry.
So on that basis would I be better keeping the input sockets isolated from earth and making an extra earth return with a decent gauge wire at the board input tags? or just fit a tag to chassis near the plugs using a serrated washer etc and rely on that for the ground return. This also looks very much like the only return path for the mains safety earth.

Regards.

Andy.

20th Oct 2020, 3:27 pm	#1
bikerhifinut Octode Join Date: Nov 2013 Location: Penrith, Cumbria, UK Posts: 1,993	Quad405 earth returns Quick question. I'm returning these 405 monoblocs back to stereo whilst the boards of one amp are in drydock. So when I reinstall a new input socket, I am assuming that because I will be fitting a pair of Phono RCA sockets that I need to take a ground return from these to the star earth by the Bridge rectifier. The 4pin din socket soldered on the original mono input board has its chassis earth connected across signal earth and as far as I can see this one tiny nut and bolt is the only earth return for the whole amp board. i.e down the input screens. I wouldn't have thought this was very good practice, not least because it relies on a mechanical return to chassis for all the circuitry. So on that basis would I be better keeping the input sockets isolated from earth and making an extra earth return with a decent gauge wire at the board input tags? or just fit a tag to chassis near the plugs using a serrated washer etc and rely on that for the ground return. This also looks very much like the only return path for the mains safety earth. Regards. Andy.