Roland Perry wrote:
In message , at 06:41:12 on Sun, 14 Feb 2021,
Roland Perry remarked:
In message , at 14:29:18 on Sat, 13 Feb
2021, Martin Brown remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on
for a few hours? That almost invariably will explain the shortened life.

When I changed the 4th one the other day, the main part was OK but the
base stub was almost too hot to hold.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics
and heat do not get on. It might be worth your while taking it apart
to check how it has failed (as I recall you are an electronics
engineer).

I'll do that (although it's more like mechanical engineering ;-)

Remarkably few components. Yes, there's an old-fashioned electrolytic
capacitor (4.7uF), plus the two-legged "red blob", four surface mount
resistors and one surface-mount ?transistor.

http://www.perry.co.uk/images/gu10.jpg

That might be a capacitor dropper. Capacitor droppers are
a potential solution on low wattage bulbs.

https://bobparadiso.files.wordpress....p_dropper2.png

More sophisticated ones are protected a bit against overvoltage.

But regular designs like that, they do not take kindly to
transients on AC supply. A brief transient can cause the
light to "flash" brightly in sympathy, and excess currents
in the LEDs, lead to their demise. I'm not sure what would
cause a "flickering fault" in such a setup - the main dropper
cap (polypropylene?) has most of the drop across it.

Paul