After looking inside an unreliable power supply, I moved on to another piece of retired electrical equipment. This motion-sensing light (Aurum Electronics model number AEC-326KA2-AC14W) overlooked my back yard for several years, installed under eaves facing west. The roof shielded it from direct sunlight from morning to noon, but it would be under punishing Southern California sunshine in the afternoon until sunset.

Sun damage eventually cracked the motion sensor window, letting rain into the sensor pod. The damaged unit would illuminate when nothing is in the yard, or stay dark when there actually is something moving. (Usually me, frantically waving.) I've installed a new unit so this one is getting the teardown treatment.

First step is to clean up years of outdoor exposure. More than just dust, there are also carcasses of dead insects and streaks of bird poop.

Inside the base is fairly straightforward. Mechanically, we can see two identical metal nuts attaching each light pod. The third smaller plastic nut holds the sensor pod. The two light pods are made of metal, the sensor pod plastic.

Electrically, green ground wire is screwed to the base, then a green ground wire enters each of two light pods. Curiously no ground wire enters the sensor pod. 120V AC power wires neutral (white) and live (black) wires go into the sensor pod. Two other wires (white and red) come back out, which are crimped to wires going into each light pod.

I can think of two ways to implement this:

  1. 120V AC power enters the sensor pod and is converted to DC power. The white and red wires coming out are DC power to run LEDs in each light pod.

  2. 120V AC power enters the sensor pod and is switched there. The white and red wires coming out are still 120V AC. Conversion to DC to run LEDs are done inside each light pod.

Which of these two guesses was correct, or perhaps it was yet another way I hadn't thought of? I know of one way to find out.

Since each attachment point is fastened by a large hex nut, turning them counterclockwise was enough to disassemble this motion sensing light into its component modules: two light pods, one sensor pod, and the base which is now just an empty metal shell. I'll look at the sensor pod first.