Amplifier Power Switch


Just trying to work out how the power switch works in this amplifier circuit. Does it switch the mains or does it operate the relays in the Psu?


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Joined 2003
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There's several models. All have a small always-on transformer for control, and one or two heavy relays to switch power to the rest of the box.


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The relay contacts see full mains voltage and current of the amplifier plus any current from the switched power outlets. The relay is controlled from some auxiliary circuit (powered from T4 in that second schematic I presume, as thats the only transformer primary that's from unswitched mains (don't be confused by the 120/240V DPDT voltage selector switch).