40W LED lamp autopsy

Why should Big Clive get all the dud LEDs to play with? :D
Three "40 watt" (yeah, right) LED lamps purchased from eBay. A few months on and two are already dead. Let's see what's failed.
PDF schematic: drive.google.com/file/d/12FQZ...
INDEX
0:00 Index
0:10 Introduction: Cheap "40 watt" LED lamps from eBay
0:47 Schematic
1:06 Fault found: five blown LEDs
2:46 Trying to make one good one out of the two
3:57 It works, but HOW MANY dead LEDs?!?
6:26 Driving one of the LED strips at the seller's claimed power
9:06 Conclusions?

[@vegisaynom]

Greetings from Shropshire! Just found your channel through the eevblog, love the content! Looking forward to seeing more videos in the new year.

[@GuTejada]

5:19 to 5:20 you can see another led failing, as old friends would say: "well, there is your problem" (another one that is)

[@AintBigAintClever]

There are a couple of flickerers on there (another one on the top cap is on its way out).

[@teravolt1195]

Bought a whole house worth of bayonets to retrofit the lighting circuit with 12V DC for a solar project. LEDs have been really resilient in mine. I desoldered the strip boards and flipped every second one so all positived were at the bottom and negatives at the top. Tooka piece of solid copper and linked them all together. I desoldered all the capacitive dropper rubbish and had hole sawn a 25mm hole in the top to drop a CC buck into I set for 1.1A. Overall they've been pretty good, but the bucks do suffer in the heat. Some fixtures hide the lamps behind a diffuser so I could hang the buck out the side. Mine were "100W" apparently but in the fine print oh they're 100W incandescent equivelant.

[@RODALCO2007]

Those led lamps are crap. I bought some E14's from ebay for the rangehood which lasted less then 3 months. I ended up replacing them with two x twelve volts led strips which I drive via a small transformer and rectifier. My set up has now worked for well over two years with no problems at all. The LED's used to be 5050 type with 3 led chips per square. Good video.

[@goamarty]

to desolder the LEDs you have to preheat the metal PCBs to something like 120 to 150 °C.

[@AintBigAintClever]

I hadn't thought of that. If I ever want to scavenge the individual LEDs for something I'll dig out my reflow station and shift them with that. Cheers! :D

[@jusb1066]

change your channel name to 'AintBigAintClive' lol

[@AintBigAintClever]

Hehe, that made me laugh out loud :D

[@pdrg]

A right pair of Celts.

[@mattmoreira210]

The LEDs can also die because of a lack of heatsinking.

[@templebrown7179]

Came here because you're on BigClive's list of recommended channels. I like your schematics a lot. Do you have Patreon or a Paypal for donations?

[@AintBigAintClever]

No I don't. I don't feel I put out enough decent content to warrant Patreon so I just use AdSense and pick up the revenue from that.

[@templebrown7179]

Ok. If you need encouragement or inspiration, I'm happy to contribute either. As for this video - your ultimate conclusion was that the LEDs in it were poor quality AND they overstated the output, right?

[@AintBigAintClever]

The LEDs weren't closely matched so some require slightly less voltage than others (and therefore get more stress when bunched with them). The strips can be driven harder than they are in this design, but that exacerbates the mismatched-LED issue and causes them to fail even quicker (although I'm testing a partially-failed strip in this video). They're definitely overstating the output power of these lamps by a significant margin.

[@kyoudaiken]

The main problem is bad thermal design as well as the capacitor dropper. Capacitor dropper circuits should be banned by law, because they are pseudo constant current sources. As long as the RMS voltage of your mains doesn't contain any peaks and kinks, it works fine. But when you have spikes they come through and fry your LEDs instantly. To get black dots you need an insufficient high voltage on the LED's die. But since their thermal design is really bad, you won't prolong the life of these bulbs much even by installing a mains filter before them. These LED bulbs are worth 3 cents in manufacturing and they are a scam, full stop. If you want decent LED bulbs, take a look at the manufacturer TIWIN, they do cold white and warm white high power bulbs.

[@Xenon777_]

One of my fluorescent starters melted.

[@wickedxe]

Are the LED's being driven too hard?

[@AintBigAintClever]

I think it may be more down to inadequate (non-existent) heatsinking. These lamps are supposed to be 40W which if you look at some of the datasheets the LEDs should be able to handle, but when you use a power meter the lamp only draws about a third of that so they should be well within spec.

[@rocketman221projects]

The LEDs are driven in parallel with no current balancing. They are probably badly matched causing some to draw more current than the others. Those ones will then run hotter and draw even more current because the forward voltage decreases as the temperature increases.

[@AintBigAintClever]

On the datasheet I found there are voltage rankings which would presumably alleviate this issue, if that is the LED manufacturer offered one and the lamp manufacturer specified one to keep them matched. greyghost.mooo.com/usb3led/BL-LS5730A.PDF page 2. This is the only 5730 datasheet I've looked at mind, I was surprised to see they could be driven at 150mA as I seem to be still stuck in the 80s where LEDs were red, 5mm wide and pulled 30mA tops :D

[@madbstard1]

Dammit - wish I'd seen this video a week or so ago cos I ordered a pack of these bulbs from ebay.

[@AintBigAintClever]

The third one appears to be in perfect working order, no dead LEDs yet.

[@madbstard1]

i ordered a pack of 5 so should have plenty of spare parts lol

[@thedavesofourlives1]

pf?

[@zx8401ztv]

Woffle is good, it gets your thoughts out in the open, i agree with having a propper heatsink on them. But (and there allways is one) it won't stop them from going poof, led's are a crap technology that are only reliable for short term use. Flourescent tubes are much longer lasting for lighting, even the cheap folded striplamp bulbs last a decent time. Only my opinion, it's what i've noticed :-)

[@jusb1066]

well there are bad leds and there were bad CFL's too, i had a few cfls that lasted a matter of about 100 hours or so, and got very hot, i think its a combination of cheap knock off leds and no heatsinking, just a cheap way of making it work 'for now'

[@zx8401ztv]

Jusb1066 Dam that was short for a cfl light, i remember when we bought an early version, it was a massive solid glass jar with the standard bayonet fitting on it, it was made by phillips and really heavy. I think it cost £20, that lasted one hell of a long time, more than 10 years before it began to play up.

[@jusb1066]

yes my early heavy philips lasted about 15 years, the ones that failed were among the last sold when they were £1 or under or given away by the gas/electric suppliers) sold by the major places when led was coming in, i guess they were badly made to reach the price point

[@zx8401ztv]

Im glad that you know about the old versions, non of my frends remember them. They were like a bomb lol, and the cord from the celing rose was oh so straight with the weight :-D

[@jusb1066]

yes i think it was about 1995, they were about 25 quid i think it was tall, a large glass covered it all, but it was for a lamp that is on all evening in the corner and the savings over 100w bulbs was what clinched the deal

[@gazyounglive]

Brighter light output by overvolting the LED's... resulting in a quick failure... easy money for the Chinese if anyone goes back for more.

[@vasvas59]

ничего не понимаю что говоришь!