Lens fell off Cree XR-E !

I have a mini-mag I converted to run Cree XR-E, but I think the light got smacked around and the reflector hit the lens or something, because the lens fell off!

Now the LED die is pretty much exposed with no protection, but it seems to be working fine.

Any reason it can't continue to work that way without a lens? I think the beam actually looks nicer without it.

By the way, it wasn't just the lens that fell off, it was the entire metal ring including the lens which is on top of it.

Oops I just noticed one of the bond wires is broken

how does the light work if the wire is broken? and dont you mean dome, not lens

rockz4532 said:

how does the light work if the wire is broken? and dont you mean dome, not lens

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It's not just a shell, it's a solid hemisphere of plastic, isn't that a lens?

As for the wire, there are 2 bond wires on each side so it still works if 1 is broken.

IIRC it is a glass dome with a metal ring around it. You can probably call it a lens because it also focuses the light but it also protects the LED from direct impact.

The LED should work fine but the loss of the dome might have affected the output and tint of the light.

I remember in one of the newbie's old posts he did it intentionally to change emission pattern to 180° (this was before SSC P4 released), and the phosphor degraded overtime so it became more or less a blue LED. The glass dome and filling probably protect the phosphors from oxidation or something.

I still think calling it a dome sounds wierd, when I think of dome, I think of a hollow shell, don't you? It's just a solid hemisphere. There is a bit of silicone that goes under the flat bottom of it, not inside it. Just my 2 cents if anyone cares lol...

Here's an illustration:



The blue part is solid glass or plastic or whatever it is, while the yellow part is silicone and the grey part of course is the metal ring. The scale isn't correct in the picture I'm sure but you get the idea.

I used to think it was like this next pic but it isn't:

i didnt think the dome focusses the beam, you can see the die from almost every angle. on the other hand, 5mm leds actually focus

A reflector hitting the emitter is a big risk of failure for lights, especially when they are dropped on their head. I see too many lights with the reflector go right up against the emitter. I try not to drop my flashlights! :candle:

It has happened to me too and there is not a lot that you can do to regain the original beam qualities of the light.
Sadly a new emitter is on the cards for you I think.

Oh well this one was old!

rockz4532 said:

you can see the die from almost every angle

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That has to do with the index of refraction, not the shape

Hellbore said:

There is a bit of silicone that goes under the flat bottom of it, not inside it.

Click to expand...

Is this some special kind of optically-clear silicone? it's odd in that it doesn't appear to cure like a silone-based adhesive, but stays gelatinous and soft, almost like a grease.

Curious, because I too have one that fell off, the metal ring/base. I had disassembled a cheap China 5 x Cree Q5 unit (http://www.meritline.com/aluminum-s...-flashlight-torch-with-lanyard---p-68226.aspx) to reflow the solder joints and properly apply heat sink compound in an effort to try and increase the efficiency of it when I knocked one off. Trying to re-affix it, the silicone grease got on the reflector and was quite stubborn to get off.

Has anyone tried sourcing this silicone compound before? I would imagine this happens fairly often? Or did we just get bad ones with silicone that didn't fully cure?

Barring any experience with fixing these lenses, I may attempt using optically clear silicone adhesive and see how it goes. My biggest concern is the heat; optically clear Si adhesive isn't categorized as "high temp", but this one for instance says it is optically clear and good for 400 deg F : http://www.masterbond.com/tds/mastersil-705

I would appreciate anyone's thoughts.

Thanks

Welcome.
Old thread, but my advice is to buy a new (and brighter) led, and swap it. A xr-e r2 led prob cost less than ultra clear silicon and its slightly brighter than the xr-e Q5 that you just messed up.

tungsten2k said:

Is this some special kind of optically-clear silicone? it's odd in that it doesn't appear to cure like a silone-based adhesive, but stays gelatinous and soft, almost like a grease.

Curious, because I too have one that fell off, the metal ring/base. I had disassembled a cheap China 5 x Cree Q5 unit (http://www.meritline.com/aluminum-s...-flashlight-torch-with-lanyard---p-68226.aspx) to reflow the solder joints and properly apply heat sink compound in an effort to try and increase the efficiency of it when I knocked one off. Trying to re-affix it, the silicone grease got on the reflector and was quite stubborn to get off.

Has anyone tried sourcing this silicone compound before? I would imagine this happens fairly often? Or did we just get bad ones with silicone that didn't fully cure?

Barring any experience with fixing these lenses, I may attempt using optically clear silicone adhesive and see how it goes. My biggest concern is the heat; optically clear Si adhesive isn't categorized as "high temp", but this one for instance says it is optically clear and good for 400 deg F : http://www.masterbond.com/tds/mastersil-705

I would appreciate anyone's thoughts.

Thanks

Click to expand...

The silicone inside the XR-E is a gel by design. Two benefits. Higher refractive index and lower stress on bond wires. No sense in trying to repair it. Just buy a new LED and swap them out.