RIFA X2 Capacitor Explosion

Bad Capacitor
Bad Capacitor

Well, this came as a little surprise. This is the PSU from a Microchip PICMASTER Universal Development System from 1993, intended for the old UV-erasable devices. On being plugged in, the PSU ran for about 10 minutes before a small explosion occurred, accompanied by an indescribable acrid smell. The photo above shows one of the X2 capacitors, across the AC input line has violently exploded, blowing the fuse (literally!) from it’s clips, and showering the inside of the PSU with bits of foil & paper. There’s another two of these on the other side of the common-mode choke, which are also showing signs of failure, however the fuse link disconnection has saved the others from the same fate.
All of these capacitors would need to be replaced with modern versions, but the PSU should still function fine afterwards. If I actually do the repair on this ancient system, I’ll do a further post.

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