I modded a lightmalls XML2-U2 and replaced with a XML2-T5 on a 16 mm pure copper pad from illumination supply and a 8 chipped 350 mAH 16 mm driver also from illumination supply I also braided bot + & - springs with 2mm copper braid.i checked tail voltage on high and got 3.25 amps I thought everything was great untill today I noticed a black spot in the center of the beam then I looked at the emitter and there is a black spot on the center of the dome,any suggestions could I try gasoline de dome method,would that help?
Curious to what has caused the black spot to appear.
Post a picture if you can…
I would think that something (maybe heatsink compound) got on the dome during the mod. This has then burned to black with the heat when the light is on. If that is the case then it should be possible to carefully clean off.
I Also have a dark spot in the center my XM-L2 mounted on copper(5A). There is no visible spot on the emitter itself.
I thought I saw a thread somewhere on BLF that this is common. I can’t remember if it was for XM-L, or XM-L2. It doesn’t affect the beam, and is only noticeable on a white wall.
Has anyone else noticed this?
You mean the typical dark spot when you shine the light at a wall from 50cm away on larger reflectors?
On larger reflector, especially one that is shallow that is normal. On a AA light with a small reflector that hole can't really be seen unless you try a 2cm away.
Take a XM-L thrower and put your finger in a way you try to cover the LED shine it at 1-2meters, you still have a hotspot. If you want put a sticker in the middle of the glass lens and you still have a hot spot.
The black spot may be from flux splatter getting on the dome when you were soldering the emitter wires to the base. Do you recall if you cleaned the emitter with alcohol and q-tip after soldering the wires to the base?.
Dedoming will get rid of the dome. So if the black spot is on the dome, you will fix the problem. Just be sure to clean the emitter real good after soldering on the wires. I squirt alcohol on the the emitter and base to rinse it off. Then I use a alcohol drenched q-tip to gently "scrub" the emitter then the base. I said scrub, but for dedomed emitters I don't scrub. More like dab the top of the dedomed emitter.
Yes, it’s a large diameter single LED thrower Reflector. The hot spot is very intense with a spot in the center on a wall in a room. More than 50cm away though.
I wouldn't de-dome a T5 - I assume it's a neutral to warm emitter. Get a really close-up look under a strong magnifier and see what's going on, if it's something on the surface of the dome or somehow marked in the dome itself. Probably something got on it and burnt.
I use a cheap 20x lighted loop from FastTech - works great! It's listed as 30x, but really 20x...
On larger reflectors like 60mm wide, the depth influences that a bit, for example JM26 has a wide shallow reflector and the black spot can be seen at 50cm while my Crelant 7G5 (first one) has deep reflector and that black spot can't be seen unless the flashlight is at 10-5cm away from the wall.
can I still try scrubbing the dome on the emitter?if I gained some thrown should I soak the emitter in gas to de dome it ?
Yes, you can try to clean it off the dome like Tom E advises. He is very talented and knows a lot more than me. Alcohol and a cotton-tipped (Q-tip). You can actually scrub the dome. Just don't put so much pressure you tear it off.
Tom E may have a point about dedoming the T5 and it getting too warm tint as a result. Most lights with T5's in my experience are on the cool side of neutral though. If you dedome, the gasoline method is generally thought of as the best way. Tom E may have been the person that thought of it first. Here is a real good thread on the topic.
I’ve got that same emitter, it’s a T5 XML2 5C1, right? That’s a nice warm LED and dedoming wouldn’t be a good idea IMO. Just try to clean it the best you can.
Also, if you’ve got an 8-350mA chip driver, it only puts out 2.8A at most. Are you using that T-Mart DMM to measure with?
OH, I'm an idiot. You said XM-L2. I've been thinking it was one of those once common place XML T5's you were talking about. So sorry about the confusion. I totally agree with Tom E and Tallboybass. Unless you want a ican like tint.
yes I am using the T-mart dmm and I scrubbed the emitter dome with alcohol and q-ti and it turns out their is a tiny hole in the dome.
Uh oh, ‘tiny hole in the dome’ can’t be good. I haven’t heard of that, hopefully someone with experience will chime in here! You might let Calvin at I.S. know, their customer service is usually really good.
Ouch, a hole, oh boy... Well? Does it still have the dark spot or did the alcohol remove it? The hole may be cosmetic, unless it's the cause of the dark spot... There's an outer hard silicone shell, then a softer inner material, so the hole may not go all the way to the emitter phosphor.
Oh - Thanx for the kind words! I didn't originate the gas de-doming, just helped make it popular by publishing details on it with my experiences from using the technique.
It sounds like something (e.g., flux or maybe a small piece of solder) hot landed on the dome and melted/embedded itself into the dome, then when that was dislodged, you now have a hole. You can either dedome it, as others have suggested, or replace the emittter.
If it were I, at this point, I’d try de-doming it, and see how it is after that, tint-wise, etc. If you like it, then keep it like that. If you don’t like it, then replace the emitter.
What do you have to lose at this point?
+1 there w/ohaya, if the beam is not tolerable as is...