Need help fixing my Bike light Exposure Race Maxx2, Where do you get LED's

My battery died on my Exposure Race Maxx2. I took it apart and replaced the LI-ON battery and everything
worked until I put it back together.

Since I didn't know which side to take a part I took both ends a part. When putting it back together the
heatsink or (star ?) lifted out of its groove and turned, this caused the optics lens to tear the optics dome off
the LEDS.

I know nothing about LED's. After many hours of searching the internet and reading the forums, I came to
the conclusion that they are some type of Seoul Semiconductor LED's from the 2008 era. I bought this light
about Dec 2008.

Specs on the light:



The light uses a pair of 18650's Li-on's tied in parallel and the LED's look like the are wired in series.

1. What type of LED's are these, there are no markings, ie model number, are these W42180-U2 ?
   
2. What is the difference between a U1 , U2 Bin ( in laymans's terms ?? I am clueless)
3. Where can I get these LED's , (in USA)?
4. Are these LED's glued to the star/heat shield or soldered ?
5. How do you take them apart ?
6. Any pointers would be helpful.

TIA
Mel


http://i1098.photobucket.com/albums/g364/hammerli22/Exposure Lights/IMG_2999_zps7d031737.jpg
http://i1098.photobucket.com/albums/g364/hammerli22/Exposure Lights/photo1_zps8931d724.jpg
http://i1098.photobucket.com/albums/g364/hammerli22/Exposure Lights/IMG_2999_zps7d031737.jpg
http://i1098.photobucket.com/albums/g364/hammerli22/Exposure Lights/IMG_2990_zpsc8da560d.jpg

Just a stab in the dark here. No pun there! lol

But, taking the dome off the LED shouldn't cause failure. In fact it should improve things! lol

I am guessing some type of grounding issue. Make sure the star is grounding properly to the body. Switch is grounding right? Clean the threads??

If you look in the other pictures you will see the rubbery dome that got ripped off the led. In fact if you look carefully at the
led's in the picture you will see it is missing the dome and you can clearly see the wafer. The lights to do not work, I have
checked and rechecked.

This is what a new looks like, but I don't know the part I have.

http://uk.farnell.com/seoul-semiconductor/s42180/p4-nat-white-emit-min-70lm-typ/dp/1778015

I was going to say that they remind me of some old Luxeon (now Philips) LEDs. A search of both of their sites might help you narrow down the part number and family a bit. Your main criteria should be the mechanical dimensions, as long as the part is nominally a 3 watt LED.
The bins just refer to the various shades of white and slight differences in efficacy (or what most folks consider efficiency). This is probably a relatively small concern.

If that doesn't pan out, you might try contacting the manufacturer and see if they can provide a new board.

I'm guessing that you are in the UK?? Exposure isn't too common here in the USA. Farnell is a well know electronics supplier in the UK, and is a good choice. The LED that you've linked to looks like a suitable choice.

Getting the LEDs off and the new ones onto the board might be the hardest part. Page 27 of the datasheet (from the Farnell site) shows that the bottom of the LED is soldered to the circuit board. You may have to heat up the whole board in order to melt the solder. I've heated up much smaller boards, the "stars" that some LEDs mount to, by placing a soldering iron on the side of the aluminum base of the star. You might try that, since there's not a lot to lose. I think others on CPF have put boards in a toaster oven (carefully) to reflow the solder, or even put it in an old skillet to do this.
At this point, getting a new board with LEDs mounted on it might be sounding like a better option.

I'd first narrowed down the problem. We don't know what's wrong, LEDs or the driver.

Let some small current flow thru each LED. Skipping the well-known warnings on powering LEDs directly from voltage source.. Take, e.g., your (charged, 4V) battery serially with a 100 ohm (or 1k, or so) resistor. This is totally safe.

All white LEDs should be pretty interchangeable. Most likely the driver will handle just fine just about any other (white) LEDs.

To check the driver.. Double-check LEDs connection. If they are really in series (unusual for 1S Li-Ion) - putting a single LED may fry it. So get two working LEDs for a test. If in parallel, then 1 can be fine. But this is not very safe (an experienced DIY-er can do it safe.. but..).

Both checks are important.. Because if both LEDs and driver are faulty.. then apparently, it's a hint from "above" to upgrade