The Ebay one I think is for the US/Canada 110 Volt AC. I am familiar with Mouser but not with that Konig stuff. They ship from Ireland I think and have a minimum order of 30 pounds or euros. It looks similar to the one in the amp.
If it helps - the switch I referred to, at Dönberg and Mouser (both of those links refer to the identical switch by the way, whatever the photos look like), is, as I said, almost a drop-in replacement. The only mechanical work needed is to transfer the NAD mounting plate, nothing has to be cut and/or glued together.
The dimension referred to above is identical to the original NAD (Alps) switch, well, it is to within 1 or 2 tenths of a millimeter, which I wouldn't worry about on a ca. 40 yrs old amp.
The dimension referred to above is identical to the original NAD (Alps) switch, well, it is to within 1 or 2 tenths of a millimeter, which I wouldn't worry about on a ca. 40 yrs old amp.
Konig was well known in the TV repair trade, generally OK quality as a lot of it is just rebadged stuff sold under that name.
Mains switches were often supplied along with about six different brackets as a 'universal' fitment across many makes and models.
It seems a lot of money just for a switch though.
Hope this makes some sense. The two diagrams show the control voltage to the FET's.
The first has the switch disconnected and the second has the switch action in circuit (simulated with a transistor) The green trace is the AC from the transformer feeding the negative rail generator, the blue trace is amplifier positive rail voltage and the red is the control voltage to the FET's.
At 30 seconds into the run the power is removed. The supply voltage for amp the slowly collapses and the control voltage in the case of no switch also collapses slowly (so no mute). With the switch and the control voltage is instantly pulled negative thus muting the audio.
The first has the switch disconnected and the second has the switch action in circuit (simulated with a transistor) The green trace is the AC from the transformer feeding the negative rail generator, the blue trace is amplifier positive rail voltage and the red is the control voltage to the FET's.
At 30 seconds into the run the power is removed. The supply voltage for amp the slowly collapses and the control voltage in the case of no switch also collapses slowly (so no mute). With the switch and the control voltage is instantly pulled negative thus muting the audio.
Attachments
thats why i repair them, they are a bit fiddly,but very doable.
its only realy dirt or where over the years they get oxidised.
the worst ones is the impedence switches as they dont very often get used,if at all.
The small signal type switches (like the front part of this one) can clean up quite well and yes, if they can be opened up then even more can be done. All things are possible 
The switches (like these) when used in TV's used to fail catastrophically with the mains part of the switch melting or one side of the switch going open circuit either permanently or intermittently and arcing.
The switches (like these) when used in TV's used to fail catastrophically with the mains part of the switch melting or one side of the switch going open circuit either permanently or intermittently and arcing.
i like the older equipment, they each have thier own personality somehow, and yes you do find some very dodgy looking workmanship, but given most were assembled by hand, and in countries that had a poorly skilled, or even unskilled work force,there has to be some credit,as the ones still going today are testimate to that.
Thanks all of you for the suggestions and help. I took the front panel off and removed the little lamp so that the switch would be more accessible. Cleaned it and sprayed inside with a 3 in 1 spray which penetrates but evaporates fast unlike Deoxit. I used the paper towel trick as Mooly suggested. Soldered the wires back on reconnected it and lo and behold the sound came right back on after the 5 second muting process. You were 100% right it was the switch. I'll probably have to change it eventually if it acts up again but as you mentioned it 30 bucks is quite a lot for a switch. Pounds, excuse me. Poundy sent this Ebay link for an original NAD switch from Germany but with shipping that was quite pricey too. But they said it was original. Anyway, right now it functions very well, thanks again
Peter
Peter
Yes, a good result - and a lot easier & cheaper than having to change the switch.
Mooly - thanks also for the additional LTSpice examples - I'd been wondering how the switch function could be easily incorporated into the simulation... turning ON was straightforward, turning OFF less so (I haven't used the PULSE option before)
Mooly - thanks also for the additional LTSpice examples - I'd been wondering how the switch function could be easily incorporated into the simulation... turning ON was straightforward, turning OFF less so (I haven't used the PULSE option before)
