My brand new SSC P4 U-bin DIED :(

I don't know if this should go in the LED or modded forums, but since it's an LED question, I'm posting here. If this isn't kosher, mods please move it.

I just received my SSC P4 U-bin on Friday for swapping out the stock 3W Lux in my LiteFlux LF1. I made the swap last night. Soldered the leads this morning after the AA set overnight. Of course, I had to play with my newly modded light. It worked great. I turned it off and on probably 20 or 30 times in the span of a couple of hours, both on high and low using a 14500 and it worked great- super bright high and fairly bright low. I then tried to turn it on another time and nothing- not even a glimmer or flash or anything.

I thought maybe the protection circuit in the 14500 had kicked in, so I tried a NiMH AA with no luck. I shorted from the body to the battery, with no luck either. So then I decided to jumper the Lux 3 removed into the circuit (parallel with the SSC) to see if it was the pill that was bad or the new SSC. The Lux 3 lit up. The SSC is dead. I removed the SSC and no matter what I do, it won't light up.

Any idea as to why this would happen? I'm at a total loss as to why a brand new SSC would only last for intermittent use in a 2 hour period. I just AAed the old Lux 3 back in place and will just have to do without a brighter light, I guess. Dang, I'm bummed!!

What is the Vf of the Luxeon and what is the Vf of the SSC P4?

Did the slug short out? If the AA wasn't thick enough it could of expanded and eventually made contact...

A slug short would have killed the driver, not the emitter.

srvctec: Which light did you mod?

Did you measure the current going through the LUXIII?


Heinz

If the positive bond wire goes to the slug of the P4, it could fuse open if the circuit goes to DD with 14500. The circuit will introduce a little resistance, but if the slug was shorted out, it would rapidly jump in current.

The light I modded is the LiteFlux LF1 as stated in my oroginal post.

The LED I swapped for the original Lux 3 is the Seoul Semiconductor P4 U bin (W42180-USV0I), color bin SV0 (5350K), Vf: I = 3.25 to 3.50V.

I'm not sure of the vf of the Lux 3, but I did the mod as posted here.

I guess I'm not sure what you mean by the slug being shorted out. This was my first emitter swap and maybe the last- with the luck I had. I thought the slug was isolated from the inputs.

Well, I think I found where I screwed up. On the SSC I just checked continuity between the slug and positive terminal and its the same point. I didn't realize this before I started. I checked continuity between the slug and positive on the Lux 3 and also negative, and it's isolated. Guess I should have done a little more research before attempting my first emitter swap.

So what is the best way to isolate the slug from potential short? Should I have just made sure to not push the LED down too much into the AA adhesive so as to leave a thicker layer of it? Or should I do something else? I'm going to order another LED to try and attempt this again, but don't really want to waste another 13 bucks!!

doh! yeah that's what happened. Best way other than an anodized heatsink, is to put a very thin layer of AA epoxy on the slug, let it cure, then attach as you normaly would.

The thinner the better but you want to make sure it's isolated.

A luxeon isn't really isolated but won't blow up if the slug touches (unless your using red, amber, red-orange as those slugs are connected to positive.). The white/other colors are fine on a negative heatsink unless you are wiring them in series, then you can run into problems.

I might just go ahead and AA the copper disk in place with a thin layer of AA on top of it and then AA the LED to that when it arrives in about a week. Dang, these learning experiences can get expensive- hope I get it right this next time. I just removed the Lux 3 again and will wait until I get the new SSC.

Thanks for your help!

I wish there was really good tutorial on general emitter swaps- I didn't come across any when searching.

Thermal adhesive like Arctic Alumina is probably the best way to attach an LED since it isolates and also provides a conductive path (yes, slap it on pretty thin as the conductivity of the adhesive is NOWHERE near the actual metal's conductivity... it's meant more to fill microscopic 'pits' and provide the bonding and isolation).

If it makes you feel any better, I've burnt $45 W-bin LuxVs 10secs within receiving them and also a few $20 U-bins and some $12 T-bins.... All part of learning I guess!

yep. i have a bone-pile of dead leds, including a cree that i just destroyed trying to remove it from the star.

I'm not familiar with the particular light, but if the original Luxeon was on a star, I don't think you have to worry about shorts to the slug. In every light I've modded that has a star, the metal under the emitter is electrically isolated, so there's no need to fuss with insulating the emitter. If anyone has encountered a star with an electrically connected LED pad, I'd like to know about it.

Also, I don't know if the light is designed to run with the cell you're using. I did a few measurements on an L0D CE with a 10440, and the LED is being pretty badly overdriven.

You should also take a close look at your thermal path, and make sure the LED is getting a good heat sink. Otherwise, it could self destruct due to overheating.

c_c

Curious_character said:

I'm not familiar with the particular light, but if the original Luxeon was on a star, I don't think you have to worry about shorts to the slug. In every light I've modded that has a star, the metal under the emitter is electrically isolated, so there's no need to fuss with insulating the emitter. If anyone has encountered a star with an electrically connected LED pad, I'd like to know about it.

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It's not mounted on a star. It's mounted directly on the pill.

Also, I don't know if the light is designed to run with the cell you're using. I did a few measurements on an L0D CE with a 10440, and the LED is being pretty badly overdriven.

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Yes it is designed to run on 14500 with the original Lux 3 and should be no problem for the SSC.

You should also take a close look at your thermal path, and make sure the LED is getting a good heat sink. Otherwise, it could self destruct due to overheating.c_c

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Actually the SSC is much more efficient than a Lux 3, so given the same current and voltage (since the driver didn't change) it should require less heat dissipation.

What does the Vf have to do with anything?

Both my LM301 are modded with SSC P4 USYNH & USWOJ and both of them has the tiny copper disc inserted between the pill and the emitter on top of the AA,so far so good.Thanks to EngrPaul for his modded experience

How long did you give the AA to cure? I know when I used it on computer parts that if you heat it up it'll soften even after it has seemed to cure. So if it was really thin it might have ran off just enough that it shorted. You need to give it like 12 hours to FULLY cure solid (it's slightly less but I like to play it safe).

If you are using the copper disc, you can apply a thin layer to that, let it cure, then epoxy it down. Then test with your DMM, if all is good, then just AA epoxy your led on with no worries then. Verify the positive lead and heatsink once more when you are done of course.

tebore said:

How long did you give the AA to cure? I know when I used it on computer parts that if you heat it up it'll soften even after it has seemed to cure. So if it was really thin it might have ran off just enough that it shorted. You need to give it like 12 hours to FULLY cure solid (it's slightly less but I like to play it safe).

Click to expand...

It was about 14 hours, so I guess I just had it too thin to start with. I actually pressed down hard on the LED (because I thought that's what I was supposed to do) which made it too thin. For my do over next weekend, after the new emitter arrives, I'll do as I mentioned above- put a thin layer of AA on the copper disk and let it cure before mounting the emitter and then NOT push it down hard.

Yes in an ideal situation you don't have to worry about isolation and you want the thinnest layer possibly. You want metal to metal contact, and the AA only to fill the microscopic pits/pores of the two surfaces. That is how I always do my mods, you can sometimes feel the metal scrape/bite and the led will stop rotating once this happens as the AA is squished out and the led is no longer floating on the AA.

But yeah for the P4 you need an inuslating layer. It's best to put it on thin, let it cure on the led, then apply more and attach as you can see the layer and verify it is fully coated and not too thick. This is better than just putting it on and not pressing down hard as you will end up with a random thickness that can be too thick and insulate heat!!!

EDIT: You do want to push down and squeeze out the excess after you have put a thin layer down first and let that harden up. Also make sure the layer you put down first is smooth and flat as possible.