Main On/Off Power Switch for various NAD Amp Models

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tiefbassuebertr

tiefbassuebertr

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Joined 2005
tiefbassuebertragung.de
#1
I need follow power switch (double switch) for replace by NAD integrated amp model 3130; one half for mains switch ON (active = Power ON, passive = Power-Off) and the other half for switch off the connection between R516 (390R) and neg pole of C520, 47uF at the same time (Active = off, Passive = on).
In my NAD model 3130 this "ON" function after performed "switch-off" serves to avoid buzzing-, bump and noise effects (through switch off the mute jFETs Q303/304, type J111) by the preamplifier output signal at the pre-out female rear cynch plugs so as the power amp input.

Where I can order such kind of doubleswitch - the NAD order code (mentioned in the service manual of 3130) are follow:
L432Y034H01 and L432Y035H01

By a wide range of other NAD models so as other brands this kind of switch is also in use. Thus it must be an universal device and not a custom made device - so I think. But I am not absolutely sure

Thank you very much for appropriate hints about brands and delivery sources so as the the popular name in colloquial english for this kind of "Power-ON" main switch.
 

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#7
Even later but worth adding info here.
The mains switches on the early NADs used a separate part of the switch to operate the on/off muting circuit. This wouldn't be allowed these days as it's not a good idea to have the signal circuitry so close to the mains. It is certainly a no-no to use one pole of a DP switch, as someone suggested.

One option is to replace the muting part of the switch with a relay, as veryheavymetals suggests. It doesn't need to be a big one as it's not switching much current, hardly any. The 3130 hasn't got a tuner and it's not a good idea to use the DC supply anyway. OK for the switch on delay but it has to be immediate to mute the preamp at switch off. Use a suitable voltage AC relay, probably with a current limit resistor, direct from the secondary winding of the transformer. I haven't tried this because I was worried about hum pickup but it's worth a try first. I used a DC relay fed through a diode and with a small smoothing capacitor, small enough to ensure quick switch off. The relay needs to have normally closed NC contacts.

The other alternative is to adapt the later circuit used in the 3020i which does not use the mains switch.

The other other alternative is to remove all the mute circuitry and install a modern protection chip which provides delay and DC offset protection for the speakers. These can be bought in kit form quite cheap. The hardest part is finding a place to fix it.
 
#9
 
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