A couple of years ago, I made a light for our porch. I wanted to ‘back-light’ the area under the porch with a subtle glow, when coming back home in the dark, handy when trying to find the front door keys. I used a clear section of hose pipe, several clips and a strip of LED tape, commonly available from lighting suppliers. I used a standard 12V power supply unit (PSU) from an electrical wholesalers’ and controlled the whole thing with a neat little PIR motion/ day-night detector. It all worked quite well until the other day.
Whilst walking past the PIR detector the light came on in the usual way, but there was a strange ‘arcing’ noise, coming from the inspection panel, behind which I’d mounted the PSU. The PSU seemed a sensible place to begin investigation.
It’s really irritating when manufacturers’ chose to make it so that a casing for something does not come apart, without breaking in to it. This PSU was made this way and to gain access, I had to carefully lever the two halves of the glued casing apart with a screwdriver, breaking the glue holding it together. It wasn’t working anyway, so what did it matter.
Looking at the printed circuit board (PCB) within the plastic casing revealed that the mains feed, presented as an IEC Kettle type connector in this case, had a ‘dry-joint’ and had begun arcing (small sparks) which left unchecked, would have caused permanent damage to the PSU.
With a small clean-up of the affected joint and a little soldering, the PSU was as good as new. Sadly, the casing won’t be the same again, but as it’s hidden out of sight, I decided that a good wrapping of electrical tape around the two halves of the PSU casing was all that was needed.
Cost of a replacement PSU: Circa £15. Cost of repair: A bit of solder and my time.