Lumapower LM-301 is a good Cree Host (Pictures missing, new ones on page 2)

[paxxus]

EngrPaul, now that I have my LM301 in my hands, more questions come to my mind. I'm struggling a little with the modification of the reflector "lip" you talk about; I made a drawing to illustrate my point.



The first drawing (I) shows how my unmodified light looks like. What I noticed is that the electrical contact c) is established by the battery tube treading against the pill d). If I untighten the head just a little the contact is lost, this is because my LM301 has anodized threads.

Now, in drawing (II) is shown what I imagine will happen if I start to remove material from the reflector lip f) which in turn will cause the pill h) to srew deeper into the head. As you can see the contact between the pill and the battery tube is quickly lost g) because the battery tube now treads against the head e) instead. Notice that this problem will occur quite soon due to the very little gap a). In fact, I can't see how I can remove any significant material at all without loosing contact.

My questions:
1. How did you avoid this problem?
2. By how much did you shorten the reflector?
3. What beam artifacts (too wide hot-spot, dark ring etc.) did you fix by shortening the reflector lip?

[EngrPaul]

paxxus,

nice drawings.

1. I did have that problem! To solve it, I applied solder to the printed circuit board, and dragged some over the eged of the brass pill (which takes solder) over top of the aluminum (which doesn't take solder, but will support the solder when compressed.) The solder bridges the gap.

2. I could only venture a guess as to how much I shortened it, .040"? Perhaps tomorrow I can bring home my calipers and compare a stock LM301 to the one I modified, and tell you the difference. Keep in mind, I used the Sandwich Shoppe Rev 2 board, which raises up the emitter higher than if you didn't.

3. I modded a bunch around the same time. If I can remember correctly, there was a dark spot in the center, and I just kept going until it was gone. I might get a tighter beam by removing more, I don't know. The beam is perfect and floody, I like it that way.

I'm having trouble logging into my photo server. When I get it sorted out I'll post some pictures of what I did for #1 above.

[paxxus]

EngrPaul,

Thanks

I understand now how you managed to get it working.

Yes, if you could manage it would be very helpful if you could measure the difference between an modified and un-modified reflector.

I'm building this light for an older person, so it has to be absolutely robust, so the mods I do must be very reliable.

[EngrPaul]

paxxus,

My picture account went bust! I created a new one.

Here is some helpful shots:

The hole needs opened so that it's slightly larger than the emitter:


You can see how much of the reflector lip I took off here with this next picture, along with my emitter. The orange Kapton tape I added because I thought something was shorting, until I figured out the body wasn't making contact with the ground connection. I left it on anyway. That's a Sandwich Shoppe rev 2 board under there.


Here you can see the solder I added to restore the connection that was lost because the pill goes in the head further:


After all was finished, here is how much gap I have (after twisting onto the solder pretty hard):

[EngrPaul]

Since my original pictures are gone here are some beamshots of a stock LM301 (Left) and a WH tint (greenish/yellow) P4 Cree (Right). Electronics unchanged.

Full Exposure:


-2 Stops:


I imagine I could have focused the beam a little more like the stock emitter was focused, but I liked it floody so I stopped short (assumably).

[Upplyst]

It was pretty easy. I got the rev.2 cree board from sandwich shoppe. The reflow soldering went well. I also had the problem with the battery connection, but fixed it with some solder lumps on the brass ring. Furthermore I pulled out the spring a bit with a pair of pliers. There is one thing, though. I am not sure if I dare to sand down the reflector lips more. There is still a black star shaped hole visible in the center of the beam when i shine it 5 inches from a wall. Should I proceed and sand some more?

[EngrPaul]

It was pretty easy. I got the rev.2 cree board from sandwich shoppe. The reflow soldering went well. I also had the problem with the battery connection, but fixed it with some solder lumps on the brass ring. Furthermore I pulled out the spring a bit with a pair of pliers. There is one thing, though. I am not sure if I dare to sand down the reflector lips more. There is still a black star shaped hole visible in the center of the beam when i shine it 5 inches from a wall. Should I proceed and sand some more?

You should judge the beam at a few feet from a wall. 5 inches is rather close. You can stack the pill on top of the battery tube with a battery, and then move the reflector in and out to see how the focus is advancing. If it seems you are not quite getting close enough, remove more material.

[paxxus]

Thanks for all the pics and explanations! I've never done a mod before so I'm a little cautious. I'm still waiting to receive the Crees and I'll order the SS PCBs today. Any reason to use the more expensive CreePCB2, the original CreePCB is only $3. I can't really imagine the "Silver filled vias" in CreePCB2 to have any relevance at the low drive level of the LM301...?

Instead of sanding the reflector, I'm wondering if I could mount the Cree on some thin copper plate/spacer instead. That should still have adequate heat transfer at this relatively low drive level. Assuming that I use the SS PCB, the height of this copper (if I can get it somewhere) should be the same as what you shaved off your reflector.

Maybe you could measure the height of your modified reflector such that I can get an idea of the thickness of the needed copper spacer.

[EngrPaul]

Thanks for all the pics and explanations! I've never done a mod before so I'm a little cautious. I'm still waiting to receive the Crees and I'll order the SS PCBs today. Any reason to use the more expensive CreePCB2, the original CreePCB is only $3. I can't really imagine the "Silver filled vias" in CreePCB2 to have any relevance at the low drive level of the LM301...?

Instead of sanding the reflector, I'm wondering if I could mount the Cree on some thin copper plate/spacer instead. That should still have adequate heat transfer at this relatively low drive level. Assuming that I use the SS PCB, the height of this copper (if I can get it somewhere) should be the same as what you shaved off your reflector.

Maybe you could measure the height of your modified reflector such that I can get an idea of the thickness of the needed copper spacer.

I don't know anything about the old cree board. You are probably right about the relatively low drive of the LM301.

Raising the emitter should be a valid way to avoid shortening the lip. The SS sells .030" copper discs for the SSC-P4, you may want to get some of these (see the Seoul LED page). It may be a challenge to accomplish.

I'll get you those measurements tonight.

[paxxus]

[EngrPaul]

paxxus,

The stock reflector measures .482" (12.24 mm)
The mod I did measures .469" (11.91 mm)

I didn't remove as much as I originally though

[EngrPaul]

paxxus,

I did a height boost to an emitter star board, when upgrading my BLIMP here:

http://www.candlepowerforums.com/vb/...d.php?t=148417

[paxxus]

Thanks! So you took off only 0.3mm, not much - I guess I'll have to sand down one of those copper discs in order to make it thinner like you did that coin in your other thread. Anyway, I'll decide which way to do this mod when I have all the parts in my hands.

[EngrPaul]

paxxus,

I didn't like how green the WH emitter was, so I replaced the emitter with a WC/X0. The color is almost exactly like the stock Luxeon.

I also filed off some more reflector to tighten the beam. It focused sharper without creating any more rings.

The result is surprisingly as good as stock, just brighter, and a fantastic spill.

[paxxus]

OK, cool. I'm really looking forward to doing this, it'll be great fun. But it won't before at least a week. I have no idea what color bin the P4s I ordered from Cutter are though. I'm leaning towards soldering a copper plate to the CreePCB and then sanding it down to the proper thickness, should be a lot easier than your coin-mod due to the softness of the copper. The copper plates from SS are about 1mm thick, so it looks like I should take perhaps 0.5mm off (1mm minus 0.3mm minus whatever more you sanded off to tighten the beam (I estimated 0.2mm)). The problem with doing it this way, is that there is no way to make adjustments once the Cree is soldered onto the copper plate. That's why I really appreciate your measurements.

[EngrPaul]

The LM301 is also a very good host for the Seoul P4. No reflector mod is necessary.

Seoul (Left), Cree (Right) in all pictures. Last picture is the same beamshot, underexposed 2 stops.

[Pumaman]

good job. looks like throw vs. flood on the seoul vs cree. I'll likely try both as well

[EngrPaul]

BTW, the Seoul is 6500K, and the Cree is WC.

I don't know what the deal is with the LM-301. The WH tint was too green for me, so I swapped the emitter for the WC shown. It's still quite warm!

[Pumaman]

seems the lower the drive level, the warmer it is, but I'm not certain thats all of it.

[paxxus]

I started out with the Seoul mod firstly since that seemed easier to do. And it was real easy. I drilled out all the vias in a Shoppe Cree PCB (rev 1) in order to break the electrical connection, and I then cut it into a little disk which I then dropped into the pit where the old lux sat. This will then isolate the positive case of the Seoul from the negative pill; everything was gunked up in thermal goo. Then I dropped in the Seoul and soldered it. Done! No sanding or anything. The throw is very good with a tight hot-spot and very nice beam overall.

I don't really like the tint of the Seoul P4 U-bin that much though, but it's still a very nice upgrade. Mine looks exactly like EngrPaul's pic.

Next up will be the Cree mod, I got P4 WG bins, not exactly WC but hopefully it's close enough. I'm really looking for a nice flood so I'm looking forward to see the results.

[paxxus]

Did the Cree mod too (WG-P4 bin). I ended up balancing two of the small SS copper discs below the SS CreePCB. No dremeling or sanding of the pill or reflector was then needed. If it sounds tricky to do, it was! But the result is very nice. My beam shots look like the ones shown by EngrPaul.

If I understand things correctly a Seoul P4 U-bin should be brighter than a Cree P4, but to my eyes the Cree is slightly brighter. The Seoul has better throw but the tint absolutely stinks. The Cree mod has IMO perfect balance between throw and spill.

I'm not going to bother with those Seouls again, unless I know the color bin.

[EngrPaul]

I've used both of these LM-301 mods (Seoul and Cree) from time to time over the last week or so. The LM-301 with Seoul is always the more useful beam.

[paxxus]

Hmm, I think I got a real lottery loser Seoul both in terms of output and tint, my Cree is definitely brighter (and white). I ordered some new Seouls from PhotonFanatic with known bin, looking forward to replacing the Seoul with a better one.

One thing I've noticed: My Cree modded LM301 kind of flickers a little, especially as it heats up (running on 1xAA Alkaline). The Seoul LM301 doesn't do this. Anyone noticed this, or do I just have a bad driver in my light...?

[EngrPaul]

One thing I've noticed: My Cree modded LM301 kind of flickers a little, especially as it heats up (running on 1xAA Alkaline). The Seoul LM301 doesn't do this. Anyone noticed this, or do I just have a bad driver in my light...?

Make sure the reflector isn't pushing on the emitter. Try backing off the pill a quarter turn and see if it goes away.

[paxxus]

Make sure the reflector isn't pushing on the emitter. Try backing off the pill a quarter turn and see if it goes away.

You solved my problem! I didn't realize how far I had actually pushed the Cree into the reflector, those two copper discs lift it almost as much as possible. When the light heated up the top terminals on the Cree must have made intermittent contact to the reflector due to the expansion from the heat. I didn't back out the pill, instead I isolated the top terminals with some thin tape. I'm not sure the tape will stand the heat long term, so I'm going to get some of that Kapton tape.



PS.: I like the Cree beam best, wonderful flood with quite decent throw, YMMV.