Great moments in Electrical Engineering

Right after the new year, the St. Isidore sound system wouldn’t power on. I was able to run an extension cord from the sacristy and replug the power strips inside the equipment cabinet so that we could turn it on and off by plugging or unplugging the extension cord. I suspected this impulse relay that allowed the 3 push buttons around the church to control the system. It had been flaky the last two summers when it was very humid. So I spent the last few months trying to track down a replacement; with no luck. I contacted a parishioner who works with sound systems and the sound person over at St. Elizabeth’s to see if they knew anyone who could fix the system or get a replacement part; no luck. About 2 weeks ago I started measuring voltage at the first power strip (which was hardwired into what I thought was the power wire coming into the box.
stis-soundsystem2
I was getting strange readings. So I decided to replace the power strips. Got some new ones, cut the wire on one, wired it into the power feed and initially it seemed to work but then it just faded out. Tried a number of other things until I finally moved the boxes with the Christmas trees that the Art & Environment team had stored under the equipment box, and this is basically what I saw:
stis-soundsystem
In my defense, I really saw the plug half hanging out so one prong was in the plug, which explains why I was getting any power at all. So mustering all the knowledge and skill I acquired earning my MSEE from Columbia Engineering, I pushed the plug all the way in. Voila! Everything works perfectly.

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