Help! Broken Luxeon lead on BB400

[JSWrightOC]

I grabbed my BB400-modified MiniMag last night only to find it wasn't up to the task. My first thought was that I may have inadvertantly left the unit on and drained the batteries, but to my delight the second time I operated it it came on, but flickered. After removing the head and inspecting the unit, I then discovered that one of the leads on the emitter had broken, flush with the epoxy case of the emitter. Of course, to keep from frying the BB400 (no load condition---ouch!) I quickly removed it and the AAs from the light. Now...I'm great at soldering, but I don't think any amount will revive this emitter, and I will probably have to obtain a new one. Suggestions, anyone? Thanks in advance!

 

[tvodrd]

JSWrightOC,

I have found the metal tabs adjacient to the leads to be electrically common to them. /ubbthreads/images/graemlins/smile.gif Just solder over to the tab. Unfortunately ( /ubbthreads/images/graemlins/frown.gif ) I have also found that BBs let their magic smoke out real quick without an LS attached.
Good luck!

Larry

 

[JSWrightOC]

Thanks for the input. I was eyeballing the tabs that you mention, and if I can find some way of securing the emitter to the module mechanically (arctic silver adhesive, perhaps?) then all I need is a little tiny bit of wrapping wire and I'm all set.

I noticed the module got quite warm during the few seconds it was powered without a load. I wonder if I have stressed some of the components beyond their specs...

 

[ksbman]

I had the same thing happen. I just gobbed some solder (I had neither the right sized solder or tip) on the module and stuck lead in it.

It has worked fine ever since, although I no longer use a MiniMag for a host.

 

[Rothrandir]

at least you didn't kill yours with a drill! /ubbthreads/images/graemlins/frown.gif /ubbthreads/images/graemlins/icon15.gif

 

[MenaceSQL]

The lead of my best of three R2H's broke off. I just used the soldering iron and melted some of the plastic around the broken lead and exposed enough of that lead and managed to solder on to it. It actually worked without me killing the luxeon. Now I have a BB500 R2H DIY Mclux to carry instead of my TK just in case if I was to lose it.

 

[shankus]

You might also try to use a Dremel to grind out some material around the lead, and then solder to it. Perhaps even some trimming with a razor blade would be sufficient?

When my MadMax burned up, there was visible smoke, and it smelled bad (Magic smoke schtanks, huh?). I think your sandwich made it.

 

[JSWrightOC]

Thank you all! I shall go home and try melting/grinding the plastic case (the idea crossed my mind)...hey, worst case situation either way is I need a new emitter!

 

[JSWrightOC]

**Update** Help! Broken Luxeon lead on BB400

Just to come full circle on the matter, I did manage to re-solder the emitter lead back to the broken-off end flush with the emitter body. By carefully melting away at the body with the tip of my iron I could get just enough solder on the two that they stuck together.. It has been repaired for about a week now and seems to be holding up just fine. Unfortuniately I had to remove the heatsink compound and re-apply new stuff...but all I had on hand was standard zinc oxide in silicone. It appears to be performing normally though.

 

[shankus]

Re: **Update** Help! Broken Luxeon lead on BB400

Excellent. A luxeon salvge team member!
I built an R2H MadMax+ with heatsink grease that is working fine. Is that what zinc oxide in silicone is?

 

[JSWrightOC]

Re: **Update** Help! Broken Luxeon lead on BB400

/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Yes, common white heatsink grease is zinc oxide in a heavy silicone oil/light grease. The particular stuff I used I bought at Radio Shack, though there are numerous other manufacturers that sell exactly the same thing.

If I had Arctic Alumina or that new ceramic stuff I would have used that...but the zinc oxide seems to work just fine.

Thanks for welcoming me to the salvage club! /ubbthreads/images/graemlins/smile.gif

 

[JSWrightOC]

Broken emitter lead spawns idea

Argh. It broke again, and this time so did the other one while I was working with it.

---HOWEVER---

I had an idea. Inspired by tvodrd and his suggestion of soldering to the tab opposite the broken lead, I managed to rotate the Luxeon 180 degrees and solder both tabs directly to the pins that are used to mount the two board layers together and transport emitter power from the inverter board below. Not only does it let me use an otherwise totally dead Luxeon, but it should also be more mechanically secure, and perhaps it will never break again. This might even be a worthwhile change in the manufacturing process. Pictures to come!

 

[IsaacHayes]

Re: Broken emitter lead spawns idea

If this is a nice Luxeon you won't want to replace in the future, maybe after you have it soldered(securly!) you should pot it in some epoxy so it's nice and secure!

 

[hank]

Re: Broken emitter lead spawns idea

My early version BB400 broke last week too, first flickered then out, and when I looked, one side of the LED was loose.
No smoke ... I just shuddered and wrapped it up in an antistatic bag, doubting I could fix it -- but just stumbled on this thread and it does sound possible.

The LED wasn't stuck down to the flat copper disk, it was flapping loose held only by the other electrical lead.

I have the "Arctic Ceramique" heatsink goop -- do I try to stick the LED down with that? I'm out of town the next week and a half, so will come back to this later.

 

[JSWrightOC]

Re: Broken emitter lead spawns idea

If you plan on replacing the heatsink compound, I reccomend you clean the slug of the emitter and the contacting surface on the module first to remove any residue. Rubbing alcohol should be a suitable solvent. I would not use anything that contains acetone, as this can damage the clear dome of the emitter (I found this out the hard way). Once both surfaces are clean and free of debris, place a *small* amount of the compound on either the emitter slug or the module, and press the two tightly together in the orientation that they will be finally installed in. Sliding the emitter in an orbital fashion will help work the compound in and spread it out. When done, while holding the emitter to the board, solder the leads in place.

Good luck!

 

[dat2zip]

Re: Broken emitter lead spawns idea

Are the ones that are breaking on the old style modules where there is no hole for the LED lead or the new style and the LED leads go into a hole in the board?

JSWrightOC,

Great idea. I will look into this immediately as this is a good suggestion. It might simplify the assembly process since it is easier to trim the LED leads this way than the current method. That and the fact that soldering both tabs to the connector pins helps the thermal properties as you can pull some of the LED heat from the leads.

 

[JSWrightOC]

Re: Broken emitter lead spawns idea

I have one of the new style modules, that has holes in the PCB for the emitter leads, and they were installed down into the holes.

I will take some pictures of what I have done and make them available for you and anyone else who might like an illustration of what I have done.

 

[Hank195]

Re: Broken emitter lead spawns idea

I have recently had the same problem with my BB400 in a mini m*g. Also sounds like a "new" style, purchased late last year. The LED lead broke at the surface of the (upper) circuit board. It looks like I might be able to solder it but there is no evidence of solder flow on the upper surface of the PC board. Although it seem to be electrically common with the surface of the PC board I want to be sure.
I wonder if the root cause of the problem is the optics exerting a torque on the emitter each time the head is twisted to turn the light on or off. The only thing that reacts this torque are the emitter leads. Is there some type of heat conducting adhesive that could be used to secure the LED? Then the torque load path would be directly through the body of the emitter and into the circuit board. That way the emitter leads would only carry electrical loads (which they are good at) and not mechanical loads (which copper is not good at, having poor fatigue properties).
As you can tell I'm a novice at this but would appreciate any recommendations. I was very happy with the BB400 and would like to get it up and running again.

 

[tvodrd]

Re: Broken emitter lead spawns idea

Wayne,

I've had 100% success (so far /ubbthreads/images/graemlins/grin.gif ) by trimming the LS leads very short, and bending them downwards and in between the 2-pin header's pins. This also saves me from having to unsolder the leads from the star boards- I just cut them.

Larry

 

[JSWrightOC]

Re: Broken emitter lead spawns idea

Hank195,

I was thinking exactly the same thing about the torque applied during the on/off twisting. A thermal adhesive would certainly fix the problem, and such a material is readily available. However, you'll never be able to replace the emitter again, but in most applications this is absolutely fine. Removing the leads altogether and soldering the tabs to the header pins has worked extremely well for me (I'm going to take those pictures right now, in fact!!) and since the tabs are physically wider and substantially shorter than the leads, they should handle the torque much better. If I break this one, I'm just going to get a new emitter from Wayne. /ubbthreads/images/graemlins/smile.gif