Dusty power supply experiment
Here’s where the fun starts. I will now take a power supply which was destined for the scrap heap, pack it with dust and lint, and load it up to 350W. The aim of this experiment is to see whether a flaring transistor can really ignite dust. The power supply used for this experiment is a Thermal Master TM-420-PMSR – a popular unit for budget PC builds, as well as for repairs on older PCs. I have found that, under normal circumstances, this power supply is capable of up to 350W, but will explode when loaded to the labelled 420W.
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As you can see, I used a lot of dust. Believe it or not, I have come across power supplies which were this bad just from four or five years of heavy use in a PC which was sitting on carpet. In one case, this did cause the power supply to explode. Fortunately for the user, they lived on the coast, and so the air and the dust inside the PC were moist – too moist to sustain a fire, and so the dust only burned slightly near the failed transistor. We will see now, though, if the result would have been the same if things were drier. I will load the unit to 350W. Although safe under normal circumstances, I have my doubts as to whether it will be able to sustain this load when it is this badly packed with dust.
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The power supply lasted about two minutes at 350W load, before one of the switching transistors exploded. The explosion ignited the lint and the fire took hold. I stepped in and put the fire out after just over a minute. The exterior of the power supply was visibly burned from that, and there were bits of melted plastic left on the load tester – possibly from the fan.
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Internally, the back of the fan was badly damaged, as was the AC wiring. Had I not put the fire out, it would have spread to other parts of the power supply, and the damage would have been much, much worse – and it would probably have been completely destroyed. Admittedly, lint is more flammable than some types of dust, but it wouldn’t surprise us if a similar result could be achieved using other types of dust, such as carpet fluff and hair. This experiment was intended to represent a worst case scenario. Below is a video of the experiment. Unlike most power supply explosion videos, I did not edit this one – it shows everything from first power up to just a few seconds before I put the fire out.
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