I've had two Philips LED lamps of the same type fail for the same reason. Arcing switch contacts. The contacts in these switches were so black that I thought they were burnt and pitted, which would be odd for a relatively low load. It turned out that they were coated in what I presume is an oxide film that wiped off easily, but was insulating enough to cause quite ferocious arcing when used.
I did a teardown on the first failed Philips lamp a while ago:-
https://www.youtube.com/watch?v=N1v0x0pG4q8
Same problem on a different switch of the same brand and era.
Arcing contacts are really bad news for capacitive dropper based LED lamps as the dropper capacitors do their best to suppress the electrical noise and in doing so pass much higher current than normal. This stresses the rest of the circuitry and can kill LEDs and inrush/fusible resistors as has happened here.
This is actually a good demonstration of a typical class X capacitor or a snubber network doing its job.
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I did a teardown on the first failed Philips lamp a while ago:-
https://www.youtube.com/watch?v=N1v0x0pG4q8
Same problem on a different switch of the same brand and era.
Arcing contacts are really bad news for capacitive dropper based LED lamps as the dropper capacitors do their best to suppress the electrical noise and in doing so pass much higher current than normal. This stresses the rest of the circuitry and can kill LEDs and inrush/fusible resistors as has happened here.
This is actually a good demonstration of a typical class X capacitor or a snubber network doing its job.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
Everything should be serviceable, why can't we get the manufacturers to cooperate?
Now it will be -10 Ohms… 😝
Um, Clive, if you still have these 1960/70s style of switches in your house I would stick my neck on the block and say your wiring is quite ancient and needs a rewire. 🙄
try using a standard dimmer on led lights and listen to the circuit breaker hum!
All the places I've lived (three of them), have had the first option you drew, for the twin switching lights.
To be fair, just how old is that switch lol
Those old switches were designed to be slow-make and break, because back in the day they were only switching small tungsten lamps, and it worked fine. I’ve got those switches and fluorescent lights (old circular ones are cool!) and you have to operate them fast & decisively, or they do arc, especially if the fitting has a power-factor capacitor across the mains. Modern switches are fast-make and break using a snap-action mechanism, and don’t suffer from arcing. You do see a brief flash sometimes as they open though!
So where do you live/stay Clive
Can I fit something to my 50 year old MK's to minimise arcing and keep the old style in service ? One has already had the removable contacts ( double sided ) reversed but is now starting to fizz a little
places a fuse to protect lamp;
makes it hard to replace the fuse without breaking everything.
nice design, Philips 👍
Yep, experienced the same thing with Osram LED lights where my bedside lamp had arc'ed at an insulation melted exposed that corroded over time.
I think you’re being a bit hard on that switch. Those MK switches date back to the 1970s!
One old sparky once told me that LED bulbs are the scourge of older switch gear. These switches were designed around 250mA to 2A, typically around 500mA in general use. He reckoned that LEDs don't draw enough current to keep the switch contacts clean. Apparently, these switches are inherently self cleaning, if enough load is applied, but LED bulbs don't draw enough current, so the contacts become oxidised and fouled over time. His solution was simple "Just use a 'real' bulb for a week or so, once in a while, to clean the contacts". I have no idea if that's wholly true, but I did try it once or twice, and for a short time there was an improvement, but then the arcing begins again. Simpler to replace with modern switches. Of course, this problem doesn't arise with a good old 'Crabtree' switch with the sliding blade contacts. Funny how proper old gear is better than the later stuff that replaced it.
we had similar problems with the same switches, they arc a lot 'cause they're rather slow make and break compared to newer switches, they just push the moving arm open slowly, not 'snap' like the new ones, our flashed horrendously on a fluorescent lamp!