Dead/flickering XM-L

It all started with Uniquefire 108S bought from wallbuys almost a year ago. As usual stock driver was promptly ditched and Nanjg 101 with two additional 7135 (with bend leads method) was mounted. Stock XM-L diode was transferred to 20mm sinkpad. Everything seemed fine but soon I started to notice flickering on low mode. After standard checks (switch, contact…) I thought that flickering was caused by damaged 7135 ic’s that were stacked to the driver. After few months I finally found time to change previously mounted 7135 and soldered new ones without bending their leads. Unfortunately that didn’t solve the problem so i finally concluded that driver must be faulty. Well today I finally decided to sort out that pesky little driver by replacing it with new Nanjg 101 (6x7135) with my “standard” firmware file already flashed. Guess what, that bloody XM-L was still flickering |( That was it ! I removed led from flashlight and hooked it up to LM2596 based CC/CV driver to sort things out, sure thing led was flickering as hell and would not even light up at very low currents. I even tried to reflow xm-l to another star but no luck. This is officially first “dead” XM-L in my collection…
As i have no xm-l’s available at the moment I used old xp-e to verify that driver is indeed working fine. I must say that xp-e at 2.2A is quite nice and with pretty tight hot spot with stock 108s reflector :bigsmile:

Interesting . Maybe a hairline crack in a bond wire ?

Hope it all works out .

Is it already flow current (at low drive current) but doesnt light up?
may be shorted ESD/reverse protection diode

those things are near bulletproof, i wonder if it was damaged during assembly somehow (but how)?
it could be defective, that seems to be unusually rare but it would be naive to think it can’t happen

you could get one on noctigon from intl outdoor or fasttech has bare emitters available

All I know that it wasn’t stressed out mechanically or thermally by me. I did some measurements few moments ago and it seems like esd diode could be the culprit as LED is conductive in both ways. Replacement is already on the way from FT…