Help w/ flickering LEDs using unknown IC - drop-in replacement?
Capacitor is your friend.
Yes, that is the classic symptoms of a cheap electrolytic capacitor drying out and raising its equivalent series resistance.
Now the ones that really matter are (in order of relevance) the one across the rectified output of the switcher. This has to charge enough during a short power pulse to keep the voltage high enough until the next one. With a high esr - that doesn’t happen. Followed by the capacitor on the controller chip’s power supply. At power on, the chip is typically powered via a high value resistor going to full wave rectified mains. That charges a capacitor fairly slowly. When the capacitor voltage is high enough, the controller starts - drawing more current from that capacitor than is flowing in via the resistor. Not to worry - a winding on the transformer produces pulses of power through a diode, to keep that capacitor topped up. Unless the latter has a high esr.
Which means buying LOW ESR capacitors of the same value and voltage from a REPUTABLE supplier - else you are likely to get some with an even higher esr.
You can cheat a tad - parallel or swap out that resistor going to the rectified mains rail. hammers efficiency - but supplements the pulse power and thus can keep the controller going - if it is just marginal.
That’s the typical situation. It is possible to get ring pcbs with magnetic standoffs and a driver module. So, either remove the existing LED board plus driver - or disconnect them. Then fit the aforementioned as a replacement. If the lamp base is steel - the magnets hold the rings in place - no screws needed.
When I buy ceiling lights, I add a spare. Which can be put in place whilst I get around to repairing the faulty one.
The lights run fine for the first few minutes, it seems to be heat-related once the board gets nice and toasty. Which cap(s) would you suspect? Just do both?
I drew a schematic at the end of the album - there’s no resistor on the rectified mains. There isn’t even a fuse on the AC input despite the board having a provision for one…
So, just swap out both caps, or replace the entire driver PCB? I’m of a mind to just start from scratch and make a 40W driver board myself for the learnings.
do you the schematics of it or maybe the picture of the board? i can’t see imgur pic in imgur website, I don’t know why, using VPN doesn’t resolve the issue
Indo_ismycountry is referring to the three blue–purple-ish barrel looking things in your 3rd image. Replace them and the flicker will vanish.
Could you have missed a “dot” off possibly? And R1, R2 and R3 are connected to HV ? In which case, the 18k is the start resistor and R2 +R3 set the output level. I also suspect that C2 is connected to the other terminal of L1. I wouldn’t have expected HV1 to go to the top of the LED chain, either. C1 is charged at twice mains frequency - so plenty of time to charge. C2 is going to be stressed rather more.
You can buy (or indeed make) an ESR tester for not a lot. Comes in handy when working with smpsu - which most psu are these days.
Making driver boards isn’t difficult. Making high efficiency ones is. That’s why the manufacturers of the chips used with them give reference board designs as well are reference circuits.
This design is live at mains, of course. Strange that there isn’t a high value resistor across C1 - that could certainly give someone touching the mains plug pins, just after it had been unplugged, a shock.
So, I would test the caps for ESR and, if you are replacing them - test the replacements. It’s not unusual to find that the replacements are worse…
It could be worth considering changing the 2.2 for a 6.8.
Here is the direct link to the schematic I drew: https://i.imgur.com/HXNFmPq.png
u/Indo_ismycountry: Are you using any adblock?
Update: I bought a cheap ESR tester and replaced the caps (upgraded 2.2uF to 4.7uF), and also added a fuse. The measured ESR on each cap improved. The flicker is still there 
I didn’t build this btw, it’s a cheap garage light off Amazon that I can no longer return.
New caps: https://imgur.com/ZOE3A7d.jpg
Flicker: https://imgur.com/gwztwKl.mp4
Measurements:
Old:
10.94uF ESR=2.0Ω Vloss=0.5%
9.636uF ESR=3.1Ω Vloss=0.6%
9.666uF ESR=2.4Ω Vloss=0.4%
2.183uF ESR=12.8Ω
2.031uF ESR=12.7Ω
2.058uF ESR=10.5Ω
New:
9.387uF ESR=1.7Ω Vloss=0.3%
8.917uF ESR=1.8Ω Vloss=0.4%
9.322uF ESR=1.9Ω Vloss=0.4%
4.149uF ESR=3.5Ω
4.147uF ESR=3.4Ω
4.395uF ESR=3.4Ω
You’re right! I’ve corrected the C2 connections. I was confused by the L1 connections since it is a transformer, but only one winding is being used.
Here: https://i.imgur.com/HXNFmPq.png
R1/2/3 go to HV2 for sure. As for the top of the LED chain going to HV1, it seems like a similar configuration to the low-side buck topology found here: https://www.power.com/downloads/documents/an67.pdf
Just with less filtering…
Update: I bought a cheap ESR tester and replaced the caps (upgraded 2.2uF to 4.7uF), and also added a fuse. The measured ESR on each cap improved. The flicker is still there
New caps: https://imgur.com/ZOE3A7d.jpg
Flicker: https://imgur.com/gwztwKl.mp4
Measurements:
Old:
10.94uF ESR=2.0Ω Vloss=0.5%
9.636uF ESR=3.1Ω Vloss=0.6%
9.666uF ESR=2.4Ω Vloss=0.4%
2.183uF ESR=12.8Ω
2.031uF ESR=12.7Ω
2.058uF ESR=10.5Ω
New:
9.387uF ESR=1.7Ω Vloss=0.3%
8.917uF ESR=1.8Ω Vloss=0.4%
9.322uF ESR=1.9Ω Vloss=0.4%
4.149uF ESR=3.5Ω
4.147uF ESR=3.4Ω
4.395uF ESR=3.4Ω
Since I don’t know how you build this and i don’t know the datasheet of you IC, i will blind guess it:
usually the culprit is C1. use better cap. at least 400V rated (if you are living in 220-240V grid). or use bigger capacitance in C2 and high rated temperature as 105C cap
if C2 is ceramic smd cap that soldered on same board with the LED esp in aluminum board, use X7 spec.
Changing the cap from 2.2uf to 4.7uf is great but it will be better if you parallel 2.2uF with same 2.2uF, so their total ESR value will be much further down and it will greatly help the life of the cap.
I’m using android phone. both my phone the older and newest one still cant display the imgur… but both using same ISP. i guess my ISP is fck me up
, it’s a cheap garage light off Amazon
How cheap… like, not worth-my-time to diagnose cheap? Garbage-quality cheap? Inexpensive-to-replace cheap?
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have you tried this light in different sockets in your home? Do we know for sure that the fault is with the light and not something symptomatic of your house wiring?
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What about this cap and that BP2863 IC? Did you replace that cap? That IC is a fast switching jfet and might be where the flickering is coming from.
If you use a VPN, ISP generally would not be a problem though.
Check their policies and stuff, there have been a lot of changes in it. Or try posting your issues in some android forum, they might be able to help you out.
Yeah like $30 USD, mostly doing it for the satisfaction.
Yep, tried multiple sockets and in an entirely different house to boot.
The cap and IC you mention are only for the center circle section, which is separate and does not flicker. It’s only the 7 rectangular panels (driven by the green PCB) which flicker.
are only for the center circle section, which is separate and does not flicker. It’s only the 7 rectangular panels (driven by the green PCB) which flicker
that is really interesting. With only a brief look at the chip, it seems like both chips do the same thing. Is this your take on it also?
I must admit, the obvious paths turned up nada and I’m not so familliar with the circuit that I could provide anything more than some experimental fault finding. My Guess is now that the satellite chips arenn’t happy about something. maybe hitting them with freeze spray, or getting them really cold might supply some evidence that there is a heat-stress, as you mentioned earlier. Otherwise, perhaps you could disconnect one or two of the satellite lights, see if the flicker stop from having less load. That might be a long shot.
The centre light, and the satelite lights, are they wired in parallel to the mains, or do the satellites get their power feed from a diode rectifier on that centre board?
Yep same functions with different implementations, I guess. I have not been able to find any data on the YT2260DE.
The centre light is wired in parallel, straight to the AC mains without rectification. It seems the BP2863 accepts direct AC input.
I’m finding it hard to find an appropriate driver to design a replacement around. There’s 26 LEDs per panel with 7 panels, and I measured ~80V per panel (each LED drops 3V = 78V needed) with each YT2260DE outputting around 320mA (times three = 960mA, divided by 7 = 137mA per panel).
80V * .96A = 77W total power. Even if I lower the current/brightness a bit, 80 * .7A = 56W. It’s hard to find an IC that can do all that at once, or even a third of it like they’ve hacked together.
I was thinking of using 7x TPS92411 - seems well-suited for this application.
EDIT: Nevermind, TI recommends some weird stacking thing with 80/40/20V per stack…