Violet LEDs turning brown

[H@rry]

I took a couple of mu DIY panels down yesterday for cleaning and noticed that the Violet LEDs were brown. It's like it scorched the outer surface or "lens". They still light up but I can't imagine they're doing any good lilke that. I got them from LEDGroupBuy and I just sent them a message to see what they will say.

I thought about trying to get the Dremel and grind the brown layer off but didn't

Anybody else had this happen?

 

[GHill762]

seems to be pretty common with the violets (from anywhere, not just ledgroupbuy).. there's been talk about newer ones not doing it, I'm sure Milad from ledgroupbuy will get you some better info..

 

[Eric B]

Yep they pretty much all do it some worse than others. I just popped off the lens cover and ran them like that until I got new ones to replace them with.

 

[H@rry]

Yep they pretty much all do it some worse than others. I just popped off the lens cover and ran them like that until I got new ones to replace them with.

How do you get the lens cover off? Twist off with needle nose plliers? Small screwdriver?

 

[jedimasterben]

The PMMA plastic lens that's used on the Chinese diodes is the cause of the issue. The LEDs still work, you've just gotta scrape off the primary lens, being very careful not to damage the diode itself. You'll also need to use a secondary lens to protect it. Pretty much every place that sells them (besides ebay/straight from China) realized that this is a problem and are now using silicone lenses that will not degrade, and some have switch to the 3535 package for significantly better thermal transfer so they'll last longer.

 

[H@rry]

you've just gotta scrape off the primary lens,

What do you use to scape it off?

 

[jedimasterben]

I have used needle nose pliers and then a razor blade to try and scrap what was left off. The LEDs still had less output bare, but with a secondary lens the difference was within margin of error.

 

[H@rry]

Good news, I emailed Milad about them and he replaced them free of charge! That's what I call customer service. Now, I hope these don't do the same thing.

 

[Reefing Madness]

But aren't the Purple LEDs the UV light? And thats what burns the lenses?

 

[GHill762]

But aren't the Purple LEDs the UV light? And thats what burns the lenses?

newer ones have a different type of lens on them that is less prone to the browning

 

[Reefing Madness]

Less prone, but its the UV that turns them brown, yes? Just like it does pvc out in the sun. Right?

 

[GHill762]

Less prone, but its the UV that turns them brown, yes? Just like it does pvc out in the sun. Right?

well for starters, LEDs we use in the hobby aren't UV, they are violet..

this is a quote from NR member "evilc66":
"This is a common problem with the generic LEDs under 430nm. The material that is used for the lens isn't rated for such a short wavelength, and as a result, discolors. I've seen this on 400nm, 410nm, and 420nm LEDs. That's not to say that all generic LEDs are built with the same defect, but it's more common than not. On the newer violet LEDs (XP style) that LEDGroupBuy and RapidLED sells (not sure about Steves at the moment), the silicone material that is used is very high grade, and shouldn't discolor over time. The lower the wavelength, the greater the chance for problems. All LEDs under 400nm will have glass lenses."

 

[Reefing Madness]

The Hydra unit uses violet, which they refer to as UV light. But mine arent old enough yet to find out if this happensm

 

[GHill762]

The Hydra unit uses violet, which they refer to as UV light. But mine arent old enough yet to find out if this happensm

I know, there are several companies that call their LEDs UV, but in reality they are above UV wavelengths. It's just another thing people are doing in this hobby that creates confusion..

 

[Reefing Madness]

Aight, that clears a few things up. ..?? I think??
So we'd actually have to find out which LEDs they are using, to classify them correctly. Would they let that info out?? If they aren't actually UV, then that would be misleading. Wouldn't it?
Mine have UV, and do not have glass lenses.

Here is what they've got:
The Widest Spectrum

The Hydra fills the visible light spectrum with light to spare. We set the standard in LEDs, and have taken our years of experience and customer feedback to provide an even wider spectral output with the AI Hydra by adding 415nm Violet and 400nm UV LEDs to the mix.

Looks like UV to me. What do you think?
http://www.aquaillumination.com/lighting/hydra/

 

[GHill762]

400nm is what they're calling "UV", which is actually the peak of that LED and above ultra violet. UV starts at roughly 380nm..

It's not AI, it's several suppliers, manufactures, etc.. They're just labeling the LED as it was supplied to them I'm sure..

 

[Reefing Madness]

Ok, but shouldn't they be using the glass lenses for the 400nm leds, as it appears its damaging them?
And in that link I gave last post, it says the purple go under 400nm. Did you take a peak at the link?
By the way, go info being thrown around here.

 

[GHill762]

Ok, but shouldn't they be using the glass lenses for the 400nm leds, as it appears its damaging them?
And in that link I gave last post, it says the purple go under 400nm. Did you take a peak at the link?
By the way, go info being thrown around here.

The "UV" says it peaks at 400nm from what I read. .

As far as I know there isn't any manufacturer in the hobby using true ultra violet, it's considered harmful not beneficial..

Idk about glass lenses, but evil is a bit of an led guru. I know a little but I'm no expert.

 

[Reefing Madness]

This all just brought us back to the original question at hand. If they had glass lenses on them, just the purple ones, then that would alliviate the problem with the plasitc lenses browning up over time.

 

[Ron Reefman]

This all just brought us back to the original question at hand. If they had glass lenses on them, just the purple ones, then that would alliviate the problem with the plasitc lenses browning up over time.

As far as I know, all the reputable led fixture manufacturers have resolved this problem about a year ago (even the inexpensive Chinese that make 'quality' products like EverGrow). They had the problem up until late 2012 and then their Bridgelux supplier solved the problem. I have 15 month old EverGrow fixtures with 420nm moonlights which are on 24/7 and the lenses are still crystal clear.