Bad Seouls?

[mitaccio]

I ordered 6 Seoul Z-power leds from Deal Extreme. I set them up in series on a Zitanium 350mA driver. I turned it on and got a small glow from the emitter on the middle led, nothing from the others. I tried each of them individually and nothing happened. I tried the driver on a spare Lux I had and it worked fine. I took a picture as well as I could to see if anyone can help. The first thing you will notice is the emitter is burned. The other things I want to point out are a pinsized burn mark on the negative side next to the emitter but under the dome, and the tab with the notch coming off of the emitter. I don't have a clue why this happened and would like some help. I think it is because the emitter was put on the star with the wrong polarity? DX says some were sent out with the wrong polarity. Can anyone help me figure out what I did so I don't burn out $35 in leds again? http://img31.picoodle.com/img/img31/4/6/7/f_seoulm_bbc4678.jpg

 

[LukeA]

That emitter isn't backwards on the star. The cathode notch matches up with the negative on the star.

The pinsized mark in the slug is the positive bond wire.

Bad things apparently happened to the other bond wires. Start a ticket with DX, this wasn't your fault.

 

[greenLED]

That emitter isn't backwards on the star. The cathode notch matches up with the negative on the star.

You sure you didn't wire the stars backwards?

 

[mitaccio]

I double checked before I turned them on to ensure the polarity was wired right. I had one by itself that also went/

 

[tebore]

With the way DX ships things I'm not too surprised you got damaged seouls.

They don't provide enough protection for the LEDs. With the seouls it's very easy to damage the bond wires and in the case of Crees to crack the glass dome.

 

[AvPD]

I tried connecting two LEDs to a Kennan driver in series and one got fried when the driver was fully powered up. I did some Googling and it turns out they need to be connected in parallel as this maintains the voltage but halves the current. In series the voltage is halved I guess but the current remains high, which must result in heat but little or no light.

 

[LukeA]

I tried connecting two LEDs to a Kennan driver in series and one got fried when the driver was fully powered up. I did some Googling and it turns out they need to be connected in parallel as this maintains the voltage but halves the current. In series the voltage is halved I guess but the current remains high, which must result in heat but little or no light.

The Kennan wants multiple LEDs to be in series (on the IC's datasheet), as do practically all other drivers, including the Xitanium series. Multiple LEDs in parallel will all eventually die due to thermal runaway, one at a time.

My vote is that the LEDs were damaged before the OP got them.

 

[AvPD]

The Kennan wants multiple LEDs to be in series (on the IC's datasheet), as do practically all other drivers

I just learned that the Kennan driver puts out a few volts less than the source, but I am certain that the OP got something wrong with configuration or current/voltage being delivered by the driver. Think of the probability of having six dead (did they come pre-burned?) LEDs in a row where the failure rate in a reel of LEDs from the Seoul factory might be say 1 in 100 at most (to pull a figure out of thin air).

 

[Black Rose]

With the way DX ships things I'm not too surprised you got damaged seouls.

They don't provide enough protection for the LEDs. With the seouls it's very easy to damage the bond wires and in the case of Crees to crack the glass dome.

I really didn't need to read that. I have four SSC P4 emitters on the way from them.

 

[Black Rose]

I think it is because the emitter was put on the star with the wrong polarity? DX says some were sent out with the wrong polarity.

Are these SKU 1445?

There is a note attached to that SKU talking about the polarity problem.

 

[SemiMan]

There is only one thing to do when you have bad Seouls, change your shoes..... ok, been waiting a while to use that one.

;-)

 

[Illum]

I've bought a couple Seoul stars from DX, none of them work

Instead of coming in packaged the way luxeons come in rolls, these were STAPLED in bubble wrap bags and tossed in zip-loc bags
as far as I know they were good to begin with but crushed to death ontheir way over.

 

[LukeA]

I've bought a couple Seoul stars from DX, none of them work

Instead of coming in packaged the way luxeons come in rolls, these were STAPLED in bubble wrap bags and tossed in zip-loc bags
as far as I know they were good to begin with but crushed to death ontheir way over.

*Note to Self: stick with PhotonFanatic for SSC stars*