Black spot in center of modded C12 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? :wink:

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...

Hey! That’s my line!

Did get rid of the black spot and it shows up in the beam a a tiny ring iam curious what could have caused that to happen?the light of seems to work fine but should I buy a new emitter and pad?

Try my hand at de doming and see how I do and if I can pull that ill go with with a XML2-U2 OR U3 im just a little bummed because it was my 1st attempt at a mod .

Since you already apparently have a hole in the dome, just soak the board+emitter in some gasoline (put some gasoline in a glass jar, enough to cover the emitter+board, and then gently drop the emitter+board into bottle, cover it up and let it sit maybe overnight. Check later and the dome should’ve floated off. The main thing is that the emitter itself get clear. If there’s gunk left around the edge after that or, ESPECIALLY around the tiny wires, DO NOT remove that. Just leave it be, as those wires are really easy to break, and it’ll be fine. After that rinse off with isopropyl (rubbing alcohol) to clean off the gasoline residue/odor, and then let it dry. Then try the emitter again (don’t be looking at it when you power it on!!).

I have run across this a few times now and in fact I just got a Lustefire triple in today with an emitter with a burnt spot on the top of it. I don’t know if it’s that something gets on them or if they are simply defective from the factory. I have de-domed them and twice I have just taken a razor blade and partially de-domed them. It seems that if you cut off the offending part of it that the burnt spot stops growing but if you leave it on and run it then it gets worse. I’m guessing that something either on the dome or actually in the dome itself is focusing heat and the dome simply burns. If you are sure you didn’t get anything on the dome then my guess is it’s a factory defect and you could ask for a replacement from whoever you bought it from. What is strange is that I have gotten several lights that had Fugic stuck on them and they don’t burn. So I’m almost thinking that it’s more likely that some impurity in the dome itself causes this to happen.

If the dedome makes it into too warm a tint, you can still use the emitter to adjust the tint of a multi-emitter light in the future. If that happens, check out some of the work done by RaceR86. It's some pretty cool stuff.

Good advice. Mixing emitters works great.