Why does a Seoul turn blue

Why does a Seoul turn blue, is it over heated, over current or over voltage?

Anyone also experience a seoul blinks in sequence for no reason?

I'm no expert, but I think it is because of heating due to overcurrent

AlexGT

It's the heat.

http://www.lrc.rpi.edu/programs/solidstate/completedProjects.asp?ID=90

Maybe its just sad

current over 1 amp will cause it to turn blue and reduce output. never seen it blink tho.

TOOCOOL said:

Maybe its just sad

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I dunno about its feeling but it surely making me sad!

Overheating. Don't let it turn blue or it'll be fried.

so is it over heating or over current? I'm lost.

I ran the same 3 SCC on parallel before and they were all fine, i took them off and remount them as quard SCC parallel and now 1 of them blinks like it's programmed to, the other one is running blue mad. the new one working just fine, I need some help before I eat them alive!

My turn mad blue when I push it at 1.2 amp, it turn back white when I return it to 700mah.

its over heating due to over current (due to over voltage)

My MTE SSCP4 turned blue on a runtime test (bad heatsinking on the emitter i found out later). After it overheated, the flashlight turned useless,it started to blink,when it was running on high for 20sec or more and after a few sec. of blinking it got dimm.

(still waiting for the replacement i orderd :candle: )

Marco

Newbie has some information about this on his Web page. It's a long single page log style page on the Seoul LED. He finds problems and questions at the top of the page, as you scroll down you see where he has found solutions and answers over time. From what you describe and Newbie's experiments it sounds like the Seoul that turns blue might have a small spot where the epoxy does not bond the die to the slug. When the Seoul heats up because of the current the spot that is not bonded to the slug heats up more than you would expect. The heat turns makes the tint turn blue much earlier than a Seoul who's die is completely bonded to the slug. The research is Newbie's. Any mistakes in my interpretation of his research are mine.

Here is the link. You will have to scroll more than halfway down the page to find the relevant information. It's worth it. He has lots of big color photos and color video on the page.
http://www.molalla.net/~leeper/seoulmy.htm

The VF of the battery is too high. I experience this with my orb raw that runs direct drive from a rechargeable cell. When the cell is fresh off the charger it's about 4.1V and after 10 sec the led gets way to hot and starts running blue.

if the voltage or current is too high that would be an easy fix since I haven't install my 4th LED yet; if it's over heated that would be a headache as I really don't wanna take the LED off again as I might kill another one by doing so. Damn, this hobby is expensive :laughing:

there seems to be the blue one having a lower vf and thus get too much current (with that parallel setup). no clue on the blinking one.

personaly, I would never run multiple Leds in parallel (and the series multiemitter run perfect)

Maybe its something with a shorting problem, even with stars used (slug on SSC is positive, You know?)

I have noticed the same, I prefer to run them at around 600 ma

Thanx for all the suggestion guys, the more I think about it, it is more likely the LEDs have different level of VF, they were all USW0I though, and the are currently out of stock from Litemania, maybe I should get some USV0I into the mix? I believe running 4 scc (currently running tri) will draw enough current from the cell and pull both the voltage and current down to acceptable level, any thought?

Senses said:

so is it over heating or over current? I'm lost.

I ran the same 3 SCC on parallel before and they were all fine, i took them off and remount them as quard SCC parallel and now 1 of them blinks like it's programmed to, the other one is running blue mad. the new one working just fine, I need some help before I eat them alive!

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I'm not sure I understand. This is what I thought you were saying. They were working in parallel, then you took them off and remounted them in parallel. After you did that, one of them had a very blue tint and one of them blinks. Is that what you said? Did you make any changes in how you wired them?

Senses said:

Thanx for all the suggestion guys, the more I think about it, it is more likely the LEDs have different level of VF, they were all USW0I though, and the are currently out of stock from Litemania, maybe I should get some USV0I into the mix? I believe running 4 scc (currently running tri) will draw enough current from the cell and pull both the voltage and current down to acceptable level, any thought?

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The only difference between the LED codes above is the tint. WO being pure white, VO being a little warmer white...vanilla colored. The I at the end signifies the Vf of the LED. Maybe the ones you have weren't consistent regarding Vf's. I get mine from PhotonFanatic (in the the dealer section here). I've ordered over 50 so far and they've been very consistent as far as binning and tint goes.

It's pretty much the heat, (due to current) so for the most part the limiting factor in how much current the LED can handle before shifting tint is how well it's heatsinked. How much metal (and surface area) the flashlight has comes into play here. In small lights, a Seoul driven really hard can turn blue in a few minutes, if not a few seconds. The same current level may be fine for a Seoul mounted in a larger light. The light in my signature line has a hefty aluminium pill that the LED mounts to. This pill threads into the body of the light, providing a great heatsinking path. Combine this with the large surface area of the light, and the LED can take 1500 mA without turning blue. I only drive the LED at 1000 mA, and it stays very cool and pure white.

Have had problems with the SSC P4 turning blue, but found out that it was overheating, bad epoxy was used to mount the emitter to the heat sink, used some artic silver thermal adhensive and now it stays white ...