My lights are usually shelf queens so i dont use them often. Just once in a while.
There aren’t any bubbles and the dome is in perfect condition. It’s just that a diagonal half of the LED is yellow when current passes through the LED, thus giving it a yellow tint.
I have seen XML2 turn yellow from too much heat, too. The old XML didnt have that problem. Can be really annoying if you notice a tint shift after reflowing..
Those are good pictures for a camera phone! It looks like the silicone of the dome detached partly from the die, which results in the same effect as dedoming: tint shift and some output loss. Interesting that it happens easier on the xml2, this will also be the reason that the dedoming is easier with those newer leds.
Anyway, that is very annoying if it happens in such an expensive flashlight, I hope they come up with a proper solution for you.
I hope that they can fix it, and esp., I hope that this is not a latent defect in the XM-L2 emitters, because I have several lights incoming that have XM-L2 emitters in them, and I’ll be ticked off if they all start doing that (dome de-laminating partially) :(!!
If it’s only happening in TN30s then it probably has something to do with the way Thrunite reflows the XML2s on. They might be using temperatures way too high. Perhaps a worker slipped and pushed a knob?
I don’t think it’s a problem with the XML2, but rather the manufacturing process of the TN30. Otherwise we’d be seeing other XML2s having this effect.
I was just checking, and one of the Amazon reviews was from Nov 2012, and the listing was under XM-L U2, vs. XM-L2, so it seems like it’s not just with the XM-L2 emitter versions, so maybe (hopefully) you’re right, that it is just a TN30 problem, rather than a generic XM-L2 problem, since the XM-L U2s have been out for awhile already?
If it happened with the original model of the TN30 with the XML, then it’s definitely not Cree at fault here but Thrunite. XML U2 came out when XML came out in 11 Dec 2012 Source
I took apart my TN31 (xml2 version) this weekend and was surprized to find just a small dap of thermal paste under the emitter base. Less then 30% of the base had thermal grease contacting it. The bigger problem though was that there was a big bump in the center of the pill. This lifted the led base off the pill so that only 3 small spots were touching the pill. The center bump and the points were the 2 screws hold the base down. Furthermore, the led itself was not fully seated. It was tilted up and has a partial gap between the base’s thermal pad and the led. I bet if I would have got the yellow led too if I kept using the light like this. Maybe, there is a similar QC issue with the TN30.