xml-u2 star wiring

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las3r

las3r

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hey guys im not sure if this is the right section but i have this >>>

xml.png


now i need to cut the star where the grey circle is can anyone tell me where to solder the + and - wires ? i see 2 soldering tabs (red circle) right next to the led and 2 on the other side (green circle) witch one is witch ?
 
There's a + on one side and a - on the other, so I would speculate that it would be just like that, but I'm not a professional at this.
 
if the solder tabs in the green circle can be used as + and - ill go that way because its not close to the led :)
 
I would use the pads on the perimeter unless you had a specific reason not to. The red ones should be part of the electrical pads on the XM-L (they should be T-shaped, not rectangular see page 10 here http://www.cree.com/products/pdf/xlampxm-l.pdf ) as it lets excess solder there flow out, and the LED will ideally end up nice and parallel to the board with minimal solder in between.

Depending on the star, the green pads could be connected, or they could be not connected, cant tell from that photo.
 
The solder pads are on the XM-L itself on the right side of your photo, they are not circled. I can't really tell what the circled spots in your pic are. But, just use your digital multimeter in diode check mode (continuity) to check from the existing clearly marked tabs before you cut the board.
On my leds from ledsupply the negative connection is on the left and the positive on the right. I am sure yours will be the same. Also, the red circled spots on the left is negative and on the right is positive but I don't have the green circled spots on my boards.

FYI there is kind of a clear waxy coating over the pads, you must scratch them with a razor or something before soldering.
 
Hi Las3r,

The 2 red circles would be where your + and - connections are. In the picture the top one will be the +.

Here is the way you can always know which side of an XML is +. If the emitter was facing with both of the little white dots on the top of the emitter, the one on the left will always be +

I am guessing the reason your cutting that down rather than just getting a 14mm star is that you were unable to locate one in the US. If you do end up cutting that one down be very sure to get all the burrs off the bottom. I'd slide it over some 2000 grit sand paper and then clean it with rub alc before gluing it. Also putting a little epoxy on the wires after you solder them to those tiny pads may be a good idea to keep the wires from tearing the pads off.
 
i might just cut the star down as much as so i can use the soldering pads then i can open up the reflector a bit if needed.
 
Looks like a lot of work and potential of damaging the emitter while your
reducing the diameter of the star.

Have you seen the Datiled 8mm XML MCPCB sold by Illumination Supply ?

My guess would be that your building a Mag mod
 
As others have already stated, the red circled connection at the top (nearest to the "+" marking) is LED+. The other red circled connection is LED-. Those are very small solder points to connect to, though. I would use a multimeter to check if the green circled connections are electrically connected to the red circled ones. If so, I'd solder to the green connections.

Similarly, if you are able to use the large, outer gold pads, I'd use a multimeter to determine if those pads are connected to LED+ and LED-. If so, I'd solder to those gold pads.
 
I am assuming las3r went with the xm-l u2 bin w/20mm pcb since Illumination supply does have smaller pcb's with xm-l's. They only have one xm-l with a u2 bin and its on a 20mm pcb.
 
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that's what i wanted >>>>xm-l with a u2 and like stated above that's the only one Illumination supply had

besides cutters but shipping is to much
 
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Those MCPCBs are very soft metal and easily cut and shaped. You could use some diagonal cutters to trim the star to near net shape and then file it to get to the desired final dimensions.

Unless you are fairly good a soldering, I wouldn't use the small solder pads on top of the XM-L itself. The small size and mechanically weak pad don't lend themselves to a strong connection. I'd use the bigger pads on the star.
 
i think what i might do is this >>>>>>>>>>
xml-1.png


and leave enough pad to solder on and cut my reflector just a hair so it does not short anything
 
i did what i posted above worked out great having a copper slug made tomorrow its about 11mm thick i think that plenty for this led
 
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