Luminus SST-40, a N4 BA bin tested

What driver can I use for this diode to achieve 6V Vf?

Hmm… You might be right…

This could also be because of different C8 hosts. I couldn’t completely screw the bezel down on the Toluene one. So it might just be different focus.

Edit: I’ll swap the mcpcb in both host and check if it makes a difference on the hotspot.

I use only nitro paint thinner and tint shift is nearly invisible . I don’t know why he got such a warm tint , seems really weird …

Yeah, that is weird. But as far as I know everyone else who uses nitro thinner gets the green tint shift. Do you boil the liquid? Does yours contain acetone?

What do you mean by tint shift is nearly invisible? Does it still turn slightly green?

Just nitro paint thinner , no boiling . No , it’s not getting green …

I don’t know what it contains . Will try to post beamshot soon

Wish you show us and explain your procedure little better. Can you Show result of your hot/cold nitro de doming vs toulene ( photo of both de domed emitters).

It seems that you discover something new and good and community will be grateful if you reveal your method. If you can show us photo of your method. I really looking forward to it.

IME when you take the dome to the bare phosphor no matter which method tint shift will happen…
I had similar results with hot dedome(2 methods of this hot de doming, there are 90% chance of leaving silicone residue on emitter after that methods and yes that will lead to less tint shift(tint shift still happens) cause there are still some silicone remains sticked to emitter phosphor surface). Solvent methods take all that silicone to the bare phosphor and they maybe even recycle micro particles of phoshor so yes there is probably a chance for even greater tint shift.

So your toulene method takes all the silicone to the bare phosphor but tint shift almost did not happened? Hmm… Well It could be…

My guess that toulene leaves some silicone residues on phosphor. Or how to say it can’t dissolve the part of the silicone that is merged with emitter phosphor surface. And if that happens it is good… Real good… Can you please show us results with photo?

I’m about to do that, just haven’t had the time to do it today… But I don’t have a specific procedure yet as I’ve only done it once with toluene. It could just be a fluke, even though I don’t think so.

And as you said, if it leaves a tiny bit of the silicone over the phosphorus I don’t mind. I happily sacrifice a bit of throw for a tint without green.

Hey Sledgestone,

do you rinse the dedomed led with something or just leave it to dry?

Good question! I didn’t clean it at all, just let it dry. After every other dedome I rinsed with isopropyl alcohol and they’ve turned out bad. So I’ve been a little suspicious that this could be part of the green shift.

Even the LEDs that I didn’t dedome but cleaned with isopropyl seem to have worse tint than the ones that I’ve never cleaned.

I was thinking that if you just pull it out of the solvent and let it dry, it’ll still have a microscopically thin coat of silicone once the remaining solvent dries. By rinsing it with IPA, you’re making sure to rinse off everything.

Yeah, that could be it. But I’m counting that as a good thing!

Sst-40 dedomed in Toluene

Sst-40 dedomed in Nitro thinner

To me it seems like the one done in Toluene has less silicone left on the phosphorus.

Hmm… I swapped the LEDs between the two hosts because I had a better driver in the one that has green tint. Guess what happened? The perfect white sst-40 is now green and the other one now has no green in it…

I don’t understand a thing… Could it be the driver that causes the tint shift? That’s the only explanation I have now.

One of the driver is a FET only with PWM and that one is the one that don’t have the tint shift.

LEDs ran on PWM will always display their tint at their maximum current IIRC, because of how the PWM works… My SST-40 gives me a brilliant cool white with little green at max output, but at lower outputs on a non PWM driver, it gets rather green.

Just thinking out loud. I know that Mitko and 18sixfifty uses FET only drivers and coincidentally they are two of the members that have reported that they dedome without tint shift. Could it be that easy?

I wonder what kind of drivers giorgoskok uses?

Fet only drivers , but i don’t think that it is important .

Check your hosts , does the one that shows green tint has an AR coated lens ? What has the other ?

No, everything is the same, two identical hosts. Both have AR-lens and to be perfectly sure I tried them without reflector and lens. It made no difference. I’m quite positive that it is because of the FET only.

I’m using triple channel drivers and the tint is purply cool white. Your results are interesting. I’m watching to see what you determine…

I wonder if the type of PWM (phase-correct PWM -vs- fast PWM) matters. I seem to remember CC and TK mentioning it impacted moonlight. Maybe it impacts higher modes too?