I have dedomed several xm-l2 with no issue but for some reason I have done a few lately that have a slight flicker but only at lower amperage. at 3 amps I cant detect an issue. Anyone with an idea of whats going on? Thanks
No ideas?
Different driver?
I tried that it will also do it using a simple resistor. It is only happening at around 2 amps or less. I have dedomed probably 400 to 500 of them and I just started seeing this. Around 5 or 6 of them have done it.
What did you do with 400 - 500 dedomed leds?
P.S. No idea about flickering under 2A, use them for one mode 3A+ lights…
I build and sell lights.
Where can we see your builds?
I build coon hunting lights. They are not traditional flash light builds, they are helmet mounted. You can see them at sunspothuntinglights.com . Totally different look from what most on this forum are used to but the same working principle.
This is very strange.
Do you know if the emitters that do that do that even before you dedome them, or only afterwards?
Also, were the emitters also from the same lot/cut tape? Or did you get them different times?
I’m wondering if maybe there bond connection is not good, maybe giving your a higher than normal resistance, i.e., there’s a voltage drop across the bond connection, so you have to get the voltage above a certain level before the emitter will light.
If the emitters are all good before dedoming but some are bad afterwards, maybe the dedoming process is causing something like that?
How are you dedoming?
I have seen that happen with a batch of emitters. Exactly same symptoms.. I only noticed flickering after dedoming, but that must have been there already before dedoming. Some of them didn't even turn on with lowest modes (0.001-0.01A or so).
The batch was reflown to copper stars by a shop, maybe doing "not-so-good" job. Reflowing them again properly helped in that case.
They are from the same tape and are not doing it before the dedoming process. I know that I am doing something to them to cause it ,but I cant figure out why they would work at above 2 amps and not below? I cant see anything wrong with the bond wires under magnification but I’m sure there is something I’m missing. I use heat and a razor to dedome.
The bond wires are probably way too small to probe with normal equipment, but what you could try is use an ohm meter across the pads on the bottom of one of the bad emitters and compare that vs. one of the good emitters. The resistance you measure will include the emitter drop, but if my “theory” above is correct, I think that you might see a larger resistance across the bad emitter vs. the a good emitter.
I will check that. I reflow them on copper myself. So if that is the problem guess who’s fault. 