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Old 20th Oct 2020, 5:14 pm   #2
Trigon.
Hexode
 
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Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 382
Default Re: Quad405 earth returns

The boards are each effectively split into two ground sections. One section is connected to the heatsink at the 'extra' screw, and therefore to the mass of metalwork. The other section is connected via the screen braid to the input socket and back panel.

R2 on each board connects the sections together but only comes into play when the board is tested in isolation, and is effectively shorted out when the boards are installed, with both grounds connected to case.

The original wiring is as follows:-

Star point at rectifier screw (3 green wires):-
1-> PSU cap(-) -> PSU cap(+)
2-> Left speaker output socket
3-> Right speaker output socket

Panel screw connection at input DIN:-
-> connector shell tag -> input gnd connection

Connector shell:-
1-> Left signal screen -> left board input gnd tag
2-> Right signal screen -> right board input gnd tag

If you look closely at the circuit diagrams, the two grounding sections are indicated by the use of rectangular and triangular grounding symbols.

Cheers

Last edited by Trigon.; 20th Oct 2020 at 5:24 pm.
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