Accidental MTG2 dedoming.

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InfinitusEquitas
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Accidental MTG2 dedoming.
Accidental MTG2 dedoming.
 
I accidently de-domed the MTG2 led inside the light Old Lumens made in this thread: http://budgetlightforum.com/node/20832
 
The light was shorting out, with the reflector making contact with the leads to the led board.  The driver worked well, and just prevented it from turning on.  To address this, small amount of non conductive paste was applied to the bottom of the reflector, and a bit of loctite added back to the threads, to prevent the head turning again by accident.
 
I was away this past weekend, and the light stopped working.  I was actually just trying to get the head off, but couldn't quite get through the small amount of loctite, despite warming it up, just by hand I couldn't get the head off, but did end up taking off the bezel.  Since I could get through that way I decided to leave the head alone.
 
While the head was still rather hot, I took out the reflector, and doing so, it of slid/pushed on the LED.  The dome just came off.
 
I thought all was lost... but surprisingly the LED still works! Big Smile
 
What's more surprising is the size of the actual emitters.  The surface area appears only slightly larger than a regular xml.  A few of the emitting surfaces did come off with the dome, but most stayed on.
 
The result is, the light is now quite a good thrower, and still puts out way more light than an XML.  Only major downside is it has a not so pretty hotspot, if you're white wall hunting, and the tint is different, much cooler, and I would guess with a much lower CRI.
 
I think the MTG2's if you're willing to dedome them, can be the best in terms of throw.
 
So question... are there are any other threads on dedomed MTG2 leds?
 
I'm curious if anyone else had the same experience or results.
JohnnyMac
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I would imagine a gasoline soaking would work justwell with the MT-G2 as it does with the XM-L emitters.

InfinitusEquitas
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I'm not sure it's really needed.  Just some heat did the trick just fine.  If I had done it on purpose, and pulled off the dome, slowly up, I think all of the emitter surfaces would have survived.

What really surprised me though, is the size of the surface... the dome makes it appear at least twice as large as it is.

ohaya
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infinitusequitas wrote:

I’m not sure it’s really needed.  Just some heat did the trick just fine.  If I had done it on purpose, and pulled off the dome, slowly up, I think all of the emitter surfaces would have survived.

What really surprised me though, is the size of the surface… the dome makes it appear at least twice as large as it is.

Hi,

Was there any clear stuff left on the emitter?

Also, are you able to do a lux measurement?

18sixfifty
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From what I have read a few people tried and failed. I don’t know what methods they have tried though. I’m almost willing to give gasoline a shot. I have five on the way but they are all kinda counted for already. Gas is the only method I have had any consistent luck with.

If anyone has tried gas please let me know. I don’t mind being a guinea pig but I don’t care to blow $20 repeating someone else’s mistake.

I’m a junky, I mod lights so I can sell lights so I can buy more light to mod so I can sell lights to buy more lights to mod.

comfychair
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I had one with a scuffed dome (stupid diamond file slipped, fumble fingers is me), scored the dome all over lightly with a razor, dropped in the gas, and... all the phosphor came off. ALL of it. In the same gas in the same jar where I left a XML for almost a month as a test and had no damaged phosphor.

ImA4Wheelr
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I did an emergency domectomy in the wee hours of the night when mod’ing my Defiant Spotlight. Used heat and kept the phosphor layer. Became warmer and threw much better. CRI seemed higher too. I had some scraps of dome left. I think if I would have used the heat of the led, the dedome would have been more thorough.

There are no bonding wires to break. It’s a tough puppy. I have reflowed the above emitter atleast 5 times. The one in the pic had wires soldered to the top around a half dozen times that night.

There are some pics in this thread:

http://budgetlightforum.com/node/20909#node-20909

InfinitusEquitas
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Hmm, might be worth a shot with just some heat, and pliers to remove the dome.  For me it came off with rather extreme ease, kind of just slid off to the side.

I'll post pictures for you guys tonight after work.

ohaya wrote:
Hi, Was there any clear stuff left on the emitter? Also, are you able to do a lux measurement?

Hi,

No clear layer left on the LED, just the phosphor dots.

Unfortunately no, I don't have any means to measure the output objectively.  Subjectively, it is significantly brighter than the xml version, but I haven't tried them side by side outside yet.  I expect the MTG2 one will outthrow the xml version.  Indoors, the light now produces the same exact kind of hotspot as the tk75.  But that's indoors, at a relatively small distance of 20-30 feet.

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If the tint has become cooler instead of warmer, you'd think that a significant amount of the phosfor has come off. can you see any phosfor on the separated dome? I'm looking forward to the pictures, can you make one of the dome as well?

ImA4Wheelr
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I didn’t mean to imply that successful dedomming with heat is easy. I think I was very lucky. The phosphor layer is not well bonded to the die. When hot, the phosphor is almost like paste. You can probably smooth it back on if any came off. I got the impression it might self level with enough heat.

InfinitusEquitas
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djozz wrote:

If the tint has become cooler instead of warmer, you'd think that a significant amount of the phosfor has come off. can you see any phosfor on the separated dome? I'm looking forward to the pictures, can you make one of the dome as well?

A layer of phosphor did come off, no question about that, but enough remained to still produce a lot of light.

I'll take pictures of the dome as well.  Just tried with my cell phone, and it didn't really come out... the dome for lack of a better place to store it, has been spending time in my wallet.

ImA4Wheelr wrote:
I didn't mean to imply that successful dedomming with heat is easy. I think I was very lucky. The phosphor layer is not well bonded to the die. When hot, the phosphor is almost like paste. You can probably smooth it back on if any came off. I got the impression it might self level with enough heat.

I know I was extremely lucky, that's a definite given... I was VERY surprised when I didn't just end up with a dead LED.  Not sure I'm willing to do anything else to the LED just yet.  I might after getting a replacement LED to put in there.

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Did it go ‘royal blue’ on ya?

“In many things in order to truly understand the small picture you have to understand the big picture first.”

True Color Rendition (TCR)/Simplified Definition: “On a scale of 1 to 10, with 10 being the highest rating, a TCR will equate to what true colors you see in sunlight vs the same object’s colors you see when illuminated with a flashlight. The closer the two are, the higher the TCR rating will be.”

The TCR Reference Standard is the Walmart Ozark Trail OT 50L , Model No. 6103.
It has a TCR rating of ‘10’. $1.00 including batteries.

InfinitusEquitas
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No, but it did shift a lot further to the side of blue.  More of a cool white, but still a far cry from XMLU2.

ohaya
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Hi,

I saw the OP late last night, and before waiting, decided to try this on an MT-G2 that was in my shorty DST (DD w/0.5ohm resistor, and 2×16340s).

I used one point of a pair of tweezers to carefully poke some holes into the dome, then I started this about 01:30 this morning, and took it out initially at about 07:30. When I took it out of the gas, there was a fairly large chunk of dome still on it, but when I just “gingerly” touched it with a small pointed stick (kind of like a longish toothpick, it popped off.

This is what it looked like at that time:

You can see the piece of the dome remnant above the star in that pic. It’s got yellowish stuff around the edges, but I think that was melted on there from when I was using the light (I think I posted somewhere about that earlier), but the main bottom part of the dome remnant was clear.

And, here’s a closer up view of the emitter with stuff still attached after that dome piece popped off:

I noticed that there seemed to be some “stuff” on one of the tiny segments, so I put it back into the gasoline for another 30 minutes. I didn’t want to leave it in there a long time, but I had an appointment, so I pulled it out. Then, when I got back, I let it soak another hour, and here’s what it looks like now:

I haven’t tested it yet, cuz I have to put it back into the light first, but anyway, how does that look? I think there’s still a bit of “stuff” on that one segment, but I don’t know if I want to either soak it more, for fear of losing the phosphors, or go poking around it, because those segments are really tiny :(. Hopefully that one piece won’t mess up the beam.

I’ll post back after I’ve had a chance to get it re-installed into the DST… hopefully it still works.

ImA4Wheelr
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ohaya, got to give you credit for not being afraid to charge into things. Nice pictures. I hate to say it, but don’t think you have any but some trace amounts of phosphor left. Should be interesting to see what the end result is. You may want to wear eye protection.

You could still use the emitter in a remote phosphor setup.

InfinitusEquitas
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Wow, nice pictures there, and nice de-doming!

Mike is nowhere as neat, and took more off the top.  I would be very surprised if that LED doesn't still work perfectly.

I see from the first picture, it looks like the dome on the bottom is completely clear.  On mine, unfortunately that (for lack of a better term) lattice, that is left on your LED, was left on the dome in my case.

ohaya
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ImA4Wheelr wrote:
ohaya, got to give you credit for not being afraid to charge into things. Nice pictures. I hate to say it, but don’t think you have any but some trace amounts of phosphor left. Should be interesting to see what the end result is. You may want to wear eye protection.

You could still use the emitter in a remote phosphor setup.

“Ignorance is bliss” :).

As I said, I saw the OP, but then didn’t wait for the subsequent posts, mentioning about dedoming with gasoline not working. By that time, I had already punctured the dome and the emitter was in the gasoline, so I didn’t have much choice except to keep going, and hope for the best :).

As far as the phosphors, I don’t know. I’m not a tint expert, but the beam color doesn’t look terrible to me.

I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one… The beam from the dedomed MT-G2 looks more like a normal CW.

I’ll try to get a picture side-by-side, but I’m not sure my camera will render the colors correctly, but isn’t that backwards from expected?

ohaya
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ohaya wrote:
ImA4Wheelr wrote:
ohaya, got to give you credit for not being afraid to charge into things. Nice pictures. I hate to say it, but don’t think you have any but some trace amounts of phosphor left. Should be interesting to see what the end result is. You may want to wear eye protection.

You could still use the emitter in a remote phosphor setup.

“Ignorance is bliss” :).

As I said, I saw the OP, but then didn’t wait for the subsequent posts, mentioning about dedoming with gasoline not working. By that time, I had already punctured the dome and the emitter was in the gasoline, so I didn’t have much choice except to keep going, and hope for the best :).

As far as the phosphors, I don’t know. I’m not a tint expert, but the beam color doesn’t look terrible to me.

I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one… The beam from the dedomed MT-G2 looks more like a normal CW.

I’ll try to get a picture side-by-side, but I’m not sure my camera will render the colors correctly, but isn’t that backwards from expected?

Hi,

For comparison (camera check), here’s a normal stock el-cheapo XM-L T6 light:

and here’s a comparison of the non-de-domed MT-G2 light (on the left, bought from CPF) vs. the newly dedomed MT-G2 light (on the right, Shorty DST):

The only way I could take this was by standing both MT-G2 lights on a table and shooting at the ceiling. Plus, I couldn’t really get them much further apart. Sorry :(…

Also, FYI, I was able to get a lux measurement of the shorty DST with the dedomed MT-G2:

After dedome MT-G2: 36880 lux (36.88 Klux)

Before dedome MT-G2: 26851 lux (26.85 Klux)

Also, correcting something I said earlier, batteries were 2×18500 Sibeile IMRs. They are not fully-charged.

InfinitusEquitas
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ohaya wrote:
As far as the phosphors, I don't know. I'm not a tint expert, but the beam color doesn't look terrible to me. I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one... The beam from the dedomed MT-G2 looks more like a normal CW.

This is my experience as well, except that if you turn on an XMLU2 light next to it you'll probably notice it's a lot warmer, just cooler compared to the regular non dedomed MTG2.

ohaya
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infinitusequitas wrote:

ohaya wrote:
As far as the phosphors, I don’t know. I’m not a tint expert, but the beam color doesn’t look terrible to me. I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one… The beam from the dedomed MT-G2 looks more like a normal CW.

This is my experience as well, except that if you turn on an XMLU2 light next to it you’ll probably notice it’s a lot warmer, just cooler compared to the regular non dedomed MTG2.

I was just re-reading your earlier post, and saw that you had said that. Isn’t that weird? All of the stuff I had read was that dedoming caused the tint to get “warmer”, whereas with my dedomed MT-G2 and with yours, it got “colder”!

Edit: I’m still a little disappointed in the dedome though. I was hoping for much higher lux than I reported above, but it was not even close to 100% increase… more like less than 50% increase in lux.

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ohaya wrote:
infinitusequitas wrote:

ohaya wrote:
As far as the phosphors, I don't know. I'm not a tint expert, but the beam color doesn't look terrible to me. I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one... The beam from the dedomed MT-G2 looks more like a normal CW.

This is my experience as well, except that if you turn on an XMLU2 light next to it you'll probably notice it's a lot warmer, just cooler compared to the regular non dedomed MTG2.

I was just re-reading your earlier post, and saw that you had said that. Isn't that weird? All of the stuff I had read was that dedoming caused the tint to get "warmer", whereas with my dedomed MT-G2 and with yours, it got "colder"!

Yup, I'm also surprised by this Big Smile  Personally I actually prefered the normal "warm" tint of the original.

ohaya
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infinitusequitas wrote:

ohaya wrote:
infinitusequitas wrote:

ohaya wrote:
As far as the phosphors, I don’t know. I’m not a tint expert, but the beam color doesn’t look terrible to me. I have another MT-G2 light that still has its dome, and I compared them side-by-side, and the dedomed one looks less yellowish than the domed one… The beam from the dedomed MT-G2 looks more like a normal CW.

This is my experience as well, except that if you turn on an XMLU2 light next to it you’ll probably notice it’s a lot warmer, just cooler compared to the regular non dedomed MTG2.

I was just re-reading your earlier post, and saw that you had said that. Isn’t that weird? All of the stuff I had read was that dedoming caused the tint to get “warmer”, whereas with my dedomed MT-G2 and with yours, it got “colder”!

Yup, I’m also surprised by this Big Smile  Personally I actually prefered the normal “warm” tint of the original.

Well, I’m topping up the 2 × 18500 Siebeles. They were only at 3.97V and 3.98V Also, tailcap current on the DST was only about 2.02 amps.

I’ve also move the DST pill “up” further towards the reflector, and I’ll test lux like that, after the batteries are fully-charged.

Also, remember, I have a 0.5 ohm resistor in the direct drive. I did that originally because I was worried about over-driving the MT-G2 :)!

I might think about trying to put another 0.5 ohm resistor in parallel, if I have the time, as there’s plenty of room in the DST’s pill, but I won’t be able to do that today/tonight, I think.

Edit:

With fully charged 2 x Siebele 18500 IMRs and moving the pill further towards the reflector, I got:

Tailcap current: 2.20 amps

Lux: 38010 (38 Klux)

So, current increased slightly, and lux went from 36.8 Klux to ~38 Klux. Not much improvement :(…

ImA4Wheelr
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That’s much better tint than I expected. I expected royal blue, but that really doesn’t have too much purple in it. I’m impressed that that much phosphor can be removed and still have a useful tint.

I wonder how much the phosphor contributes to output. We need someone that knows more about this stuff to chime in.

ohaya
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ImA4Wheelr wrote:
That’s much better tint than I expected. I expected royal blue, but that really doesn’t have too much purple in it. I’m impressed that that much phosphor can be removed and still have a useful tint.

I wonder how much the phosphor contributes to output. We need someone that knows more about this stuff to chime in.

I don’t know for sure, but I think that, maybe, one thing I did different was what, as I said, I was really concerned about leaving the emitter soaking for a really, really long time, based on some comments about the phosphor being “like paste”. I was really worried that if I just left it like that, all the phosphor would “drift off” (my mental picture).

That was why, when I got to the point of trying to get the larger clump of stuff off of the emitter, I didn’t just leave it in there, but pulled it out before I went off to my appointment, and also why I hesitate soaking it again now, to get that last tiny piece of stuff of off that one segment.

Again, I don’t know. I know others, including comfy, have said that they left XM-Ls in gasoline for weeks, but maybe the chemical composition of either the phosphor or the dome are different for the MT-G2s than for the older emitters like the XM-L?

All I know is what I did, which seemed to work “ok”, and hope what I documented helps others…

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Yeah, I would call it a success. Many people prefer the tint you achieved. Especially, for throwers. I applaud your efforts and reporting. Good stuff. I hope you get that baby to 100% more throw.

ohaya
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ImA4Wheelr wrote:
Yeah, I would call it a success. Many people prefer the tint you achieved. Especially, for throwers. I applaud your efforts and reporting. Good stuff. I hope you get that baby to 100% more throw.

Thanks.

I don’t know about that last thing though. I just was outside, comparing it to my STL-V6 with dedomed XM-L, and, even with the spill effect masking the throw, it was pretty clear that the STL-V6 spanked the DST :).

My last hope is adding the parallel 0.5 ohm resistor, but I kind of seriously doubt that’ll make up the difference. Would definitely be nice, but I’m kind of doubtful.

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Based on djozz’s test results on severly overdriving the MT-G2 (It survived 16A), I think you can probably get rid of the resistor all together. Do it at your own risk, but I would try it if I had that setup. I think it will not go over 5A, maybe 6A and only for a short time as the cells drain.

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relic38 wrote:
Based on djozz’s test results on severly overdriving the MT-G2 (It survived 16A), I think you can probably get rid of the resistor all together. Do it at your own risk, but I would try it if I had that setup. I think it will not go over 5A, maybe 6A and only for a short time as the cells drain.

Will do, but, not purposely being a “doubting Thomas”, but I think “lumens <> lux”.

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ohaya wrote:
I’m still a little disappointed in the dedome though. I was hoping for much higher lux than I reported above, but it was not even close to 100% increase… more like less than 50% increase in lux.

Perhaps if you get a bigger reflector?

Slewflash 

ohaya
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I just was thinking (it happens :)!): If the MT-G2 tint gets cooler when it’s dedomed, does that mean that lumens would increase, rather than decrease with a dedomed MT-G2?

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If lumens increased, then why would the dome be on in the first place? Shocked

Slewflash 

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