KEF PSW2000/2010 Active Sub Woofers

UPDATE

Because of the number of issues I have seen with KEF PSU2000 sub-woofers, I am no longer accepting repair jobs on them. The mechanical construction makes them awkward to work on, and they seem to have just too many almost insoluble problems.

However, I leave this page up as it may be of interest or useful to some.

SUMMARY

These boxes, made by British manufacturer KEF, are floor standing cubes that are about 35 cm square. They contain a single bass speaker, some preamp electronics and a power amplifier.

In this article I describe some modifications which makes them run cooler. This should help their long term reliability. Two are described : one is a redesign of the low voltage power supply. The other is a simple mechanical change which allows air to flow in and out of the enclosure that houses the electronics. I also give some measurements I made of the internal air temperature, with and without the mods.

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Rebuild Of A Soundcraft CPS150 Power Supply

Soundcraft CPS150 PSU

This PSU belongs to a Soundcraft Delta 200 desk which I restored. It is pretty old. On first inspection the output voltages were correct, the only problem was that the mains transformer made an annoying buzzing sound. Looking more closely, it had other issues.

This post shows the kind of things I pay attention to when restoring or rebuilding old equipment. The devil really is in the details with this kind of work.

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