Up for sale here is this new Alps SDU3P power switch. This is an extra-fancy switch and is the correct replacement for a number of switches on some vintage NAD, Realistic, Marantz, Concept, Sanyo, Luxman, and other receivers from the 1970s and 1980s. It will replace the power switch in the NAD 3130, NAD 3150, NAD 7155, Sansui A-5, A-7, A-9, A-60, A-80, AU-X1, 3900Z, 4900Z, 5900Z, Sanyo 2050, Sanyo Plus 75, Sanyo JCX-2600K, and Sanyo JCX-2900K.
If the rear section of your old power switch attaches to a circuit board, then this is the correct power switch for you. The cheaper green switch that I have available will work fine if you have wires that attach to the rear section of the power switch, but if the rear section goes into a circuit board then the green switch will not work properly.
This is identical to the old Alps SDU3P power switches, except that it has no metal mounting bracket. You will need to carefully remove the metal mounting bracket from your old switch, install it on this switch, and then install this switch. It's actually really easy.
You will most likely need to install a snubber capacitor for this in order to protect it. I have those available here, if you don't already have one.
Installing this is simple--just wire it up exactly like the old one, using the new snubber capacitor to replace the old one. If you don't see a snubber capacitor attached to your power switch, just wire it across the AC terminals.