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EEVblog 1481 - Dodgy Dangerous Heater REPAIR

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A heater that doesn't heat up should be an easy and quick repair, right? RIGHT?
This Arlec space heater also has a rather dodgy and dangerous construction!

This is a classic fault in capacitive droppers. And since I'm the family's repair shop I keep a good stock of class X and Y caps.

D'arlec >>> EXTERMINATE - EXTERMINATE!  :scared:

In this application using a usual 630V (DC) film cap is fine. Actually in most of the cases non safety rated capacitors are used for such droppers. Most likely X2 capacitor was used with no safety requirements in mind. Probably it was even a cheaper and more common part since produced in larger numbers. Not that many 220n 630V usual caps are needed these days but X class will be in most of the mains powered equipment. Even if this cap went short, 47R resistor would blow and open the circuit.

A failing cap in a capacitive dropper supply is very common. It is not just cheap Chinease ones, but also the top brands. I may be less of an issue in the US or other 110 V countries.  If the capacitor is not class X the series resistor should be a fusible one. As 220 nF is quite common for X class caps it absolutely makes sense to use one there. It still makes sense to have a resistor that fails gracefully.


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