A Perfect Dedome?

For “wires” i meant those hair-thin copper wires on the led die. Mine is also disconnected. The problem was that a silicone chunk that remained on the die with the copper wires in it were loose, so i thought it released the wores, i could simply push it away from the led.

My first XML dedoming in progress (XPG was a fail :frowning: ), will see how it turn out…

I burned up an XM-L (& driver) while bench testing a driver recently (thanks to RaceR86! - just kidding man) and so I was about to toss it in the trash when I had this idea to try and dedome it by soaking it in gas. I had not brushed up on the technical details on what to do and didn't have time to so I just threw it in a plastic cap with some gas and set it aside (cap was about 1 inch wide and 1 inch tall and I only put about 1/4 to 1/2 inch of gas in it). I checked on it every now and then and finally plucked it out about 2 hours later. The dome just fell off and it looked fairly clean. I then doused it with some rubbing alcohol to rinse it. I did try applying power to it to see if the gasoline brought it back to life, but no such luck . I'm sure if this LED had been a working one I would have failed.

Here's a pic (best I could get with my phone):

-Garry

Mine ended up kinda OK-ish, but tint shifted to more-green :Sp which I don’t like too much…

Do we have a guide as to how far tint shifts based on the tint you start with before dedoming? I know generally speaking that dedoming will move you to a warmer tint, but how far? What is the "best" cool white tint to start with so as to end up near a nice neutral white tint (i.e. 4C tint)? Start with a 1C? 1A? Or is it not this simple?

-Garry

I saw a nice post of maybe 3 different tints, and their resulting de-domed tints - not sure where this was. I like the 0D and 1A's de-domed - 1A turns neutral but not too much yellow - much like a 3C or little less. 1C's definite more yellow, I'd say more so than a 3C. I accidentally de-domed a 3C and wow - ton of yellow but looked nothing like the T3 6A1 and T4 warms I've seen - the de-domed 3C was much more yellow than the warm tints, in fact the warm tints seem to me to be more of a true pale white while the 3C is more yellow.

Well thanks to RaceR86 i know that de doming of cold white emitter(6500) upper neutral white color appears(around 4800) which has little greenish tint visible in aspheric and not so visible in reflector. This de-domed tint looks much better to me than cool white but don’t ask me; you decide.

Guys if you are not familiar with tint colors it looks something like this:

I would say its beneficial to start with 1A/1D instead of 1B/C.

On the tint chart, most emitters seem to end up 1300-2100K to the left, and then some up (towards the green/yellow spectrum) You will not end up with anything as nice as a 4C no matter where you start in the CW range.. A 2A would probably get you "close" to a 4C in terms of temperature. But it could still not compete in color rendition or color tone IMO. I have not measured this stuff, so I dont have hard factual numbers. I have seen texaspyro show some stuff on temperature change, but I have never seen any numbers on color tone.


Luminarium, your are learning. :) Although the pictures you are showing are for describing temperature (kelvin), not hue.

I’ve found through trial and ONE error (XR-E) that dedoming an XP-G2 R5 2B (CW) on a noctigon:

http://intl-outdoor.com/noctigon-xp20-mcpcb-cree-xpg2-r5-2b-led-p-723.html

:and put in a DD zoomie gave me a really sharp die image, and it retained a great amount of ‘cool whiteness’…

But, when I dedomed another XP-G2 R5 2B (CW), this time on a alu star:

http://intl-outdoor.com/cree-xpg2-r5-2b-led-20mm-mcpcb-p-705.html

:and again mounted in an identical DD zoomie, I got the green tint… everso slight on zoomed in mode (again a nice sharp die image), but quite visible on flood!

Clearly the Noctigon copper base helps immensely.

Cheers all

Rob

RaceR86 - that's what I was thinking - de-doming would take you 3-4 cells over to the right, and maybe 1 up on this chart: http://flashlightwiki.com/images/c/cb/Ansi-white.jpg. Don't think your link is working, not sure if the ANSI white chart is what you meant.

Link works for me.

-Garry

Yesterday tried my first gasoline dedome, in EU unleaded 95 gas (here called "benzina", if anybody cares).

Worked like a dream, both emitters came out of the overnight bath clean like the dome was never been there, wires area too! GREAT!

But clearly I underestimated the color shift: on noctigon XML2 T6 C3 became so yellow it looks like those french car headlights from the early eighties...

And on octigon XPG2 R5 B2 went slightly better but has a definite green hue.

Now ordered XML2 U2 A1, hope the tint remain better...

Did my first dedoming for a TR-J19 build. Soaked the emitters in gasoline overnight and cleaned them up this morning. Tested them and they all work. :)

did the gasoline affect the gold coating on the back?

Not that I noticed. They look perfect. I was worried about the phosphor layer before dunking them but it is solid on all of them.

Isopropyl alcohol should be used to clean em up - I squirt it directly on the phosphor giving the whole star a god shower, then perfect. Btw, I sand down the nickel/gold on the backside using 2000 or 2500 grit - they come stock pretty smooth but just to be sure to remove small burrs on the edges... Soo much easier/better than SinkPAD's.

My second attempt went quite well. The dome didn’t fall ott, but it has small cracks in the silicone, so i thought it is ready to rock.

Then i easily popped off the dome with a toothpick, and let it dry. There is some silicone near the bond wires, but the wires are embeddeded, and didn’t dare to remove.
IMHO it will affect the beam pattern in a reflector light, but i won’t try to remove that goo. Maybe with an xm-l2 which has fewer bond wires it could be done.

EDIT: 118 kCD throw, not bad :smiley: Could be better with xm-l2 :confused:

Good job!

Why do I believe the LED seal is actually a repurposed can of high temp silicon based clearcoat?

http://www.autozone.com/autozone/accessories/VHT-Paints-Gloss-clear-high-temperature-engine-enamel/\_/N-25gw?itemIdentifier=465393_0_0\_

Just marked up 2x?

Chemicals safe to use on Cree emitters without discoloring them
http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/XLamp%20Application%20Notes/XLamp_Chemical_Comp.pdf

Because you're hopelessly jaded, probably don't believe in the Great Pumpkin, either.