Yesterday SWMBO turned on a light switch and there was a loud bang. Today I discovered that an electrolitic capacitor in a GU10 lamp had exploded forcing the front diffuser and the LED pcb out of the glass. Diffuser was only plastic so it didn't break on hitting the floor; the rest was held in place by the wiring.
I've never heard of this particular fault before.
LED lamp?
had exploded
Ah. yes.
Diffuser was
shouldn't be using electrolytics really..or was it an LV one?
the lamp was run off mains voltage. 4 diodes (as a bridge) straight on the mains followed by 3 resistors with the electrolitic across the supply to the LED board.
what a bad way to do it
Of course if one of the LEDS go, so does that cap..
A closer look shows the 24 LEDs in series.
I've had a couple do it - in the early days of mains LEDs. Quite put me off them, given they weren't cheap.
Of course if one of the LEDS go, so does that cap..
Well, capacitors that go bang are not a new phenomenon. I had an old b/Q compact tube with bc base used in a shed do this some years ago, I suspected the temperatures anddampness had somewhat knackered it. It was only tiny but it made a mess, nonetheless. The LED psus are somewhat more complex so probably more of these little critters inside. I'm still not sure what the thing did in the compact, anas removing it and plugging it in produced light! Brian
Very crude and inefficient it sounds like. Brian
Another one to watch out for are those ever so cheap usb chargers. Seems in amny cases fuses are not only not included, but the whole lot runss directly on the mains with a teeny weeny transformer and a small bridge rectifier and regulator with naff looking eelectolytics inside all held together by two cassette sized screws. One mains spike and it frazzles. Brian
Resistors are often fitted as fuses.
PSU cases that get so warm that their fixings snap or halves become unglued, guts lie open, and offer a fright for enquiring fingers in the dark.
Since almost being electrocuted thanks to such a PSU supplied with a Maplin USB Hub, I've changed habits and employ the use of a torch to visually find things plugged in - not fingers...
Brian, be carefull!
We had a Halogen bulb do that. It's on a timer, in a desklamp, and SWMBO asked why it hadn't come on when she sat down in the evening. Investigation showed that there were lots of tiny bits of glass scattered all over the table top and carpet, and just the BC base and some wire left in the lampholder. This bulb probably came from CPC, although I can't prove it. I'm glad it did it when nobody was switching it on at the lampholder.
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