Compact Fluorescent Failures

Matthew Smith · 2005-04-05T02:44:52+00:00

Greetings Over the last couple of months, I have had a spate of failures of compact fluorescent lamps (electronic ballasts). (All of the lamps in our house, barring the ones that aren't kept on for any time, are CFLs.) Whilst a couple have been generic Far-Eastern ones, I've had a couple of failures of Philips units as well. (Back in England, one of the first Philips electronic CFLs was still running well after seven years.) One failure was within a week of installing a replacement - that went straight back to the shop for replacement. (I've taken to writing the installation date on the base.) In another, the electrolytic capacitor had failed (end blown out); I replaced it and it runs fine, although I have yet to replace the thermal fuse. Of the others, it's a bit of a mystery; I've performed the following tests: * Check appropriate DC voltage exists after bridge rectifier. * Check electrolytic capacitor out of circuit. * Check switching transistors out of circuit. I'm now painstakingly tracing the circuits of two of the Philips units so that I can mark up some voltage readings against "healthy" units. I was rather surprised to find that even the latest units are constructed with through-hole, discrete components. (What, no integrated switcher?) None of the fittings are enclosed that the units would be getting particularly hot. We are on a single-wire (19kV SWER - read "highly unreliable power supply") HV system - I don't know if this might have any bearing on the problem (spikes, etc). Some questions: 1) Does anyone have any figures for commonest causes of failure? (In other words, where do I look first?) 2) Are the thermal fuses essential? Not all units seem to have them - at least that I can identify. Whilst I'm not one to go removing safety devices willy-nilly, more recent units do seem to have slightly lower component counts, fuses included in some. Should I fit thermal fuses to ones that don't have them? 3) Are these devices...

Apr 05, 2005 20 Replies

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James Sweet 21 years ago

Those are electrolytic cap failures for sure, there's no epoxy holding them together but when a capacitor really goes it can blow it's top and knock things out of the way. Never had that happen but it sounds exciting.

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