Flicker from middle set of 3 plinth LED lights Ask questions and find answers to many subjects relating to electrics and electrical work

[Willbill]

HI, I have some small round LED lights in a plinth around part of the kitchen, there are 3 sets of these lights, the Middle set has three lights and those on either side are sets of two. They were all working fine till two days ago, when the middle set of three started flashing, the sets on either side are working fine.
I have lowered the wiring from above the plinth, there appears to be a mains cable going into a Down Voltage Converter with a 240v input and a 12VDC output. a wire comes out of the 12VDC end to what looks like a junction box, which the wires feeding the three lights are plugged into it. However this junction box has a circuit board inside ? My thoughts only, I was wondering if this was some sort of starter motor (like the used to have on the old fluorescent lights) if it is and its gone wrong, I have no idea whats its called and where to get one from.
Your guidance and advice on this matter would be greatly appreciated .
Yours.
William Scott

[ericmark]

My thoughts is an electrolytic capacitor has failed, however where the failed capacitor is I don't know.

[Willbill]

Many thanks, I will try to look into that

[ericmark]

I had a G9 LED lamp fail, ordered new one, but thought I would have a look inside. [attachment=1]G9-big.jpg[/attachment] When I got the shell open I found a clear dry joint so re-soldered and back into service, however there was a large electrolytic capacitor after the full wave rectifier which would have been simply too big to fit inside the other G9 lamps I have [attachment=0]G9-small.jpg[/attachment] the whole lamp is about the size of the smoothing capacitor in the larger one.

What seems odd is use one large G9 LED or a G9 quartz with the smaller lamps and they don't flicker, they are powered from an electronic switch which does not require a neutral and I would assume flicker due to some interaction between switch and lamps.

Also had it with dimmer switches with quartz lamps, it seems the coil in the lamp was a critical frequency for the electronic transformer.

Fact you are using DC there should be in theory no problem, so looking at what can change, and the electrolytic capacitor has a limited life, so that is the most likely component to fail.

The electronic power supply is full of electrolytic capacitors, the AC in is turned to DC and charges a electrolytic capacitor then the DC is turned back to AC in kHz range then transformed down, in kHz range the transformer can be much smaller, it then is turned back into DC again an electrolytic capacitor and the output voltage is sampled and the mark/space ratio of the devices generating the AC are adjusted to correct the voltage.

Because the control goes around in a circle it is near impossible to repair, it is simply a fit a new one job.

[Mr White]

Obviously it has something to do with this "Junction box" but unless you can identify what is wrong and have the ability to change the troublesome part I can only suggest you change all the lights to something more suitable, most kitchens use "What ever light is in vogue" at the time of installation, so it is possible that the lights you have are no longer made.

[ericmark]

[quote="Mr White"]"What ever light is in vogue"[/quote] Oh that brings back memories, Dad had a Singer Vogue Estate and I believe it means to carry or transport in style, and it did have small twin head lights, but I am sure that is not what you mean.

There has been a problem which copying ideas found in magazines and show rooms, as often the rooms shown have high ceilings, and [attachment=0]98361719_10158572386853420_1054327038518755328_o.jpg[/attachment]this may work in my sons kitchen, although not so sure about the bike, but most kitchens as simply not high enough ceilings, even so I suggested he set them to emulate the great bear, may as well go whole hog and make room like a planetarium.

OK his is quite new, but the problem is often no earth wires for the extra low voltage, and so can't be swapped to low voltage, and cables over 1 meter long so many switch mode power supplies can be used due to becoming a transmitter with longer cables.

Added to that although some LED lights have smoothing capacitors many don't and cause medical issues due to the flashing. And although toroidal transformers last for decades, the same is not true with any volt dropper that uses an electrolyte capacitor. And I have found where they must have been fitted from above, and will not fit through the holes.