Fixing flickering led lights

[tsvi]

Hi there,

A quick intro, I studied electronics about 15 years ago and fixed a faulty capacitor here and there. So I do have some knowledge, but since my main expertise is RTL simulation my hands on knowledge is quite limited.

Lately two led lights on my house started having some weird behavior so I wondered maybe I could fix them easily (like the faulty capacitors I replaced on a motherboard and another one in a LCD screen a few years ago).

One light started flickering when turning on, after about 7-8 flickers it stays on constantly.
The other one also flickers when turning on. It then stays on for a few minutes after which it goes off, and then starts again: flickering, on, off, flickering, on, off, ...

All of this behavior reminds me of my studies when we studied capacitors.

So now to my questions:
1. How do I figure out what's happening?
2. What should I measure and where?
3. What's the easiest fix (except for obviously buying new lamps)?

I hope this is the right place for such a question.

Thanks in advance,

Tsvi
 

[SteveThackery]

In my experience this is quite common with cheap Chinese LED lamps.  They usually have tens of LEDs, and one or more might flicker.

I've read somewhere that it is usually a bonding wire lifting off the chip when it gets hot. It then cools down and makes contact again, and thus the cycle repeats.  I don't know for a fact if this explanation is true.  I've found that if you wait long enough the faulty LED will usually stay off permanently, so the flickering disappears.

Other than that, the only thing you can do is buy a new one.

I am no expert - hopefully one will be along soon. 

[Poroit]

G'day tvsi,

What type and brand are your LED Lamps?

https://mm.mmem.com.au/lamps-lighting/lighting/downlights-spotlights?p=1

[jpanhalt]

LED household lights are nice, but the 5 to 7 year life expectancy on the boxes is deceptive.  It's really 2 to3 years of relatively steady  light and 3 to 4 years of flicker.  Maybe the flicker is designed to save energy and reduce carbon emissions.

[inse]

The bond wire topic is also what I know.
Time ago I poked around at a dead LED array with a chop stick and momentarily made one LED go on again.
But repeatability was low afair

[Gyro]

LED household lights are nice, but the 5 to 7 year life expectancy on the boxes is deceptive.  It's really 2 to3 years of relatively steady  light and 3 to 4 years of flicker.  Maybe the flicker is designed to save energy and reduce carbon emissions.

The best bet these days is to buy the highest wattage ones you can get and do a 'Big Clive' on them to reduce the light output and operating temperature by snipping out one of the current sense resistors. That only works from new of course.

eg. (He has several on the subject)... https://www.youtube.com/@bigclivedotcom/search?query=hacking+led

[RJSV]

   Sometimes you can suspect the original house and lamp having minor corrosion on contacts.  But that's the case if a whole set of LEDs flickers,  not if just a couple flicker.

   In fact,  the 120 volt or 240 volt ac type aren't really serviceable,  but they get into flickering due to not drawing much current;  so the fixture contacts can corrode.

(You didn't say what type, or post a picture,  but sounds like you have access to the individual LEDs ?)

[kmm]

I've read somewhere that it is usually a bonding wire lifting off the chip when it gets hot. It then cools down and makes contact again, and thus the cycle repeats.  I don't know for a fact if this explanation is true.  I've found that if you wait long enough the faulty LED will usually stay off permanently, so the flickering disappears.

This is what I suspect the failure mode of one of the backlight strips on my Samsung LCD monitor was, it was not only sensitive to thermal conditions (one side flickered on cold start, went away after ~10 min warming up) but also could be coaxed into reviving faster for a good few months with a solid thwack on the side of the monitor. Problem resolved when I replaced the affected backlight strip after it died completely and it's still my daily driver monitor a year+ later, so the problem does seem to be something physical in the LEDs themselves.

The other common failure mode in general lighting LEDs is apparently the bootstrap capacitor (iirc that's the name, I believe it couples a small amount of mains current into the LED driver chip to get it going) getting cooked by the heat of the lamp, which leads to a similar-looking but more stark (flash rather than flicker) ~1hz failure mode that's common in things like street and other outdoor lighting fixtures. I haven't done much with repairing mains LED drivers though, I'll repair a $200 monitor but a $5 bulb just gets tossed (very "green"), most of that I've just gleaned from watching Big Clive.

[bostonman]

In my area the power company pushes for free home efficiency inspections. The company hires a 3rd party company who evaluates your house for free, replaces incandescent bulbs with LEDs, etc...

I was reluctant, but had them come. They replaced all my bulbs and left the old incandescent ones with me should I need them. They also installed a different filter on my sink faucet that allows less water to come out (I found this silly as it just means I need to waste more personal time waiting for more water)

Within a day I noticed one bulb didn't turn on and about five or six in different rooms blinked.

Upon calling them, their solution was to swap back the incandescent bulbs. My argument was: the state (or federal government) is funding them money to perform these "upgrades". They in turn are getting paid, installing cheap LEDs that fail, and telling the customer to revert to their old bulbs.

I spent several weeks complaining until they finally returned and handed me a full set of bulbs for my entire house.

My personal opinion are many LED bulbs are junk because I see street lights blinking, mine blink, and I've heard/read many stories about them failing in no time.

Unfortunately I think we are all a victim of being forced to go "green" but at the cost of companies alluding the government into thinking they have the solution to reducing emissions so they get funded more money, however, the home owner pays the price by having to replace stuff that doesn't last as long.