Power Distribution and thermal shut off for S12

I got tired of the million AC cables coming out of my S12 racks and across my floor and audio snakes in the machine room and decided to make a stand!!!

I had been switching my console on by individually switching each power supply “on” which was getting vary annoying as well. And then I’d have to go to a sub breaker box and turn it on and off to stop Harrison’s “fans on forever” mode from happening. That is, even when the power supplies are switched off…. the fans keep running.

So ….I made a power distribution box with solid state relays which have “zero switching” AC. that is, they switch on when the AC is in its zero position of the alternating wave after it receives a little DC control voltage (3-32 volts DC) . So no spark or surge when switching on.


You can use a little flip switch, or any kind of switch to control sending the dc current to the SSR (solid state relay+ I have the + side of the dc control voltage ( I used a 12 volt supply i had lying around) going to a thermal switch, which is just a fancy thermostat (got it for $25 bucks on ebay) which is set to be a normally closed connection or “NC”  in normal operation. When the temperature rises above whatever temperature I set as a threshold (I have it set to 82 degrees F for now) then the connection becomes normally open or “NO” in “alarm mode”.


You can literally have an alarm go off as well if the the temperature is exceeded.

Basically now I have thermal protection, and one large AC cable instead of 7-8 AC cables (cut down about 40ft of AC cables!!).  I have routed the single large AC cable forward away from all the audio connections to the floor in front of the racks. A safe way of turning on everything related to the console with no sparking, arching and having to turn on individual racks. Zero crossing ac switching that is basically impossible with a regular relay or by switching everything with all the amperage present on a large mechanical switch. I also wired up a AC feed to a switched outlet for the Mac IIVX computer and Geffen extender box (sends video and ADB/keyboard/mouse of the Mac IIvx up to 500 ft over CAT5 cable)  so it also gets switch power via the SSR.

Thats it!

All this was done for about $145 U.S.D. worth of parts. Which just for the thermal control alone would’ve been worth it. Relays are $25 each … i could’ve used only one but opted to use a separate phase for the control surface and computer related things and kept all audio related stuff on its own phase.



  1. November 30, 2012  2:22 pm by maikol

    Great Stuff Shawn, well done! I should do something like that...

  2. November 30, 2012  2:23 pm by Shawn Sullivan

    Thanks, you can do it! And your switch can be wherever you like since it only carries a little dc current. I can and have touched my fingers across the 12v terminals of the dc control voltage switch and cant even feel any current flow. I did this to show my Intern that it is completely safe even in a human to ground fault condition. You can remote the switch in your control room if you like as well. Since the switch is 12 volts DC (it can be 3-32 volts range) you can hookup a little indicator 12 volt lamp or LED for a couple dollars and you are Golden!

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