Mod/Fix SK68/Cree 7w 300 type light?

Excited to join the forum! I fried my sk68 type light. I love the size and the beam focus. The 1 AA is great.

I ran it for maybe 10 minutes with a GTL cheapie 14500 and it quit. The switch&battery seem fine. Took it apart and nothing looks fried. ?. There doesn’t seem to be a heatsink.

I would like to fix it or put a brighter led in. Looks like I’ll need a heatsink. Any suggestions?

Try to narrow down the cause of the fault. You might start by simply trying a normal alkaline battery in case the 14500 shut down, then bypass the tail switch with a paper clip or such, look at the underside of the pill/driver for any faults, and then take a closer look at the solder connections that you think are OK. I’ve had what appeared to be fine solder connections to the LED fail in a light that ran very hot. Also take off the front lens/tube assembly and make sure nothing is shorting in case something melted a bit and allowed a short. If all else fails, be thankful that it’s an inexpensive light that you are learning on…

Thanks Rob. I tried the switch in another one and it worked. Also used Christmas tree hook to get that light going but not broken light.

Tried different battery still no go.

Looked under magnifying glass, a corner of the emitter is not there. Also neg looks like it maybe suffered too much heat. Is that enough to kill emitter?

Probably won’t be cost effective to fix but a cheap education :slight_smile: will probably try to fix or upgrade it anyway. Learning electronics

Hard to tell without pics, and maybe with ’em. The nice thing about a cheap broken light is that you don’t hesitate to do the autopsy. If you have a soldering iron you could try refreshing the 2 LED pads since you say the neg looks questionable. It shouldn’t have failed in the first place after 10 minutes, which gives you a pretty good indication that it wouldn’t be worth upgrading to a “better” emitter. If it were me, I would keep playing with it a while longer and then eventually keep it for parts. If it was a recent purchase you might post the vendor so others would know to be wary of SK68s from him. You might also consider the other style of little AA zoomie that’s out there now in both 3 mode and single mode, more easily pocketable. Link to one of many sellers, just so you see a pic: http://www.ebay.com/itm/600-LM-CREE-LED-Zoomable-Focus-7W-Q5-Mini-Zoom-Flashlight-Torch-light-/291097132261?pt=US_Flashlights&hash=item43c6bdbce5

Thanks for the tip I’ll have to keep an eye on those. Just bid on one.

Yeah I’ll probably try lighting it up with a single aa too. I’ve heard it woproject in partybe.

Id like to get it working although might wind up spending $20 on a $5 flashlight. Heatsink suggestions? Trying to figure out led lights, educational project partly, suggestions welcome.

Not 100% sure on sellers but hobbymate.rc sent the nicest one.

http://s25.postimg.org/fb3yzo01r/P1210973.jpg

the shelf the led pcb sits on is part of the head, so the head is the heatsink.

… What do you mean by ‘no heatsink’?

Hollow pill?

We need some pics!

It could have been a junk emitter, poorly flowed onto the star causing the emitter to fry. Sk68’s are often driven pretty hard for tiny 14500/AA lights.

If the pill is just hollow I wouldn’t worry about it. Replace the emitter and star for a few bucks and you should be good.

This thread should be helpful: LEDs & Other Stuff - (Reference Guide)

OK had a tough time but here is a link I couldn’t get it to post from smartphone

http://s25.postimg.org/fb3yzo01r/P1210973.jpg

Is cree 7w300 the emitter? What’s a good driver? Or is mine maybe/ probably good?

Hollow pill, no big deal.

The emitter looks like it is improperly flowed into the star. Looks to be crooked. If you remove the star+led from the pill you may be able to get it working again by simply heating up the star and repositioning the emitter (it needs to be turned clockwise just a little bit.)

I have seen on the forum and have used the method

Get a pre ’84 penny (think it was a 77), sand it smooth on both side, drill a hole directly in center and put it on a dremel/rotary tool cutter wheel attachment

spin it on a file to turn it down till it fits down in the pill cavity that the emitter sits on, then use artic silver epoxy to glue it in, glue the emitter base on top of that (you have to drill holes for wires of course)

Me and my kid actually did that last night.

Unfortunately I didn’t get pics, I have a UltraFire zoomie (I also saw a post on the forum here showing why if the led sits spaced from the aspheric lens the flood pattern diameter is smaller. I wanted to actually remove that space and have the led almost touch the back of the aspheric lens in unzoomed mode for maximum flood. Me and my kid sanded and turned down a penny, reflowed a copper sink pad to it and moved the XM-L emitter from the aluminum base to the now approx 3/32” copper slug (first attempt shorted the emitter, I had to reflow again but it worked the 2nd time) and I swapped out the driver from the crappy 5 mode (Hi, Lo, Strobe, SOS) to a Nanjg 6*6135 STAR V1.1 firmware.

Original aluminum emitter base was approx 1.4mm thick, the sink pad was 2mm and the penny was another approx 1.4mm, they reflowed and soldered together perfectly on the stove…I should have gotten pictures

I also am going to try a few of my SK68 conversions and reflow a few XP-G emitters on 16mm sinkpads and do the copper spacer trick, a friend is working on a 15mm Nanjg 5*7135 105C compatible build for me…but it’s on hold for more pressing builds at this time though

If you notice the SK68 the emitter sits WAY back from the aspheric lens and is usually held in by a plastic ring with interference compression…if there is a solid base where you can epoxy/RTV it down you don’t need that retention ring

And another design flaw of the zoomies. the nice pretty heatsink fins and/or the mass of the flashlight, are actually thermally isolated from the body and pill by the slider o rings…one way to ensure the heat that does get absorbed by the pill flows thru the aluminum to the fins is to apply a small amount of NOALOX to the threads, not only does it help in making it easier to screw in, but also helps a little in providing a better path for heat to wick away

That XP-G is definitely twisted on it’s solder pad…usually a reflow the solder will suck the solder pad above it straight when it get’s liquid again, might be able to get that to work, if not, when the solder melts, snag the LED with a pair of tweezers, lift and set back down, surface tension should straighten it out…then re-assemble

Well…just for grins…I took a XM-L on 16mm pad, unsoldered one of the XP-E’s on one of the 6 SK68’s I have left, soldered in a the XM-L, alot brighter…yeah, I know it’s a bit of overkill and a waste but just putting in an XM-L over a XP-E and nothing else changing the light brighter all things being equal…threw a 14500 in it, and wow…impressive, focus is a bit off but still zooms down but the light is considerably brighter (alas it’s subjective, only way of knowing is putting it on a meter)

I just got one of those a couple days ago.

Pretty impressive actually. Much smaller and slimmer than an SK68. Even smaller and slimmer than an SK58. It also has the widest flood mode I’ve seen in any zoom light yet, coupled with a very tight hotspot, equivalent in brightness to an SK68.

Biggest downside for me is I don’t think I can get a Nanjg 105c to fit like I can with the Sipiks. There just isn’t enough space inside the body tube. I’d pretty much have to file off the entire negative contact ring.

On the other side of the pill, there’s only room for a 14mm star. So I’d have to grind down a 16mm Sinkpad to fit for an XPG2.

It works!!! Between pulling the wires off the star, putting them back on, and putting the star on a stove, heating it up and straightening it out, ( with toothpicks) it works! I think it was straightening it out that did it. Thank you everyone.

Is that all I have to do to mount an emitter? Pretty easy if I did it right. Probably more to it than that.

Sanded down one side of the penny, if I remember right ’83 had both copper and the new ones, so you might use 82 or older. I used ’76-D. I don’t have a dremel do you think I could put it in a drill somehow?

Glad to see some mods. Thanks guys. These are nice little lights I thought someone would be moddimg them. Should I attempt to put an xml-l2 / 1.5 amp in there?

Won the auction for the Cree 600-LM. Looks even smaller than 7w 300. Look forward tog getting it.

Basically the further out the lens is, the more focused it gets, until you reach the focal length or so. I got about 13 mm for the one on the 7W 300. What about just taking off the front lens? Maybe too wide?

Thanks again,

Congratulations, Mike. You are now officially a journeyman apprentice, and as such you are entitled to read the secret knowledge, such as Old-Lumens posts. Seriously, though, the other style of AA zoomie that I linked to has several advantages. It is smaller, lighter, and more easily pocketable, it tends to have a broad, even flood without rings, and it is much easier to hold in your mouth when you need both hands free. At around $4 shipped it’s not bad. The only single-mode one I’ve had was very bright on a 14500 (and hot) so I gave it to someone who would only use it on an alkaline. The lens tends to scratch easily after a while in your pocket since it is so close to the front, but a good little light.

We replaced my son’s with a XM-L T6-4C on a 16mm base…(bought a cheap one from FT)

I recommend getting a pre ’84 or ’82 pure copper penny, sanding both sides smooth (or cut out a disk from a sheet of copper :wink: ), drilling a hole in the center, putting it on a rotary tool cutoff wheel attachment, use sandpaper (takes a long time) or a hobby file less time) and turning it down till it fits on the shelf (not inside the shelf, on the shelf like a solid pill), epoxy/RTV it down, drill wire holes (make sure they line up with the emitter base), then epoxy/RTV the emitter base to said penny, then solder down the wires (you won’t need the retaining ring to hold the emitter down once you epoxy/RTV it down…viola, heatink…not the best, but will work better

If you REAAAAALY want good heatsinking, get a 16mm copper sink pad, then braise/solder the penny and the emitter base together on the stove, use tweezers to pull the emitter off the aluminum base (and paying very very very close attention to polarity) stick it on the new copper base) you will have gone from approx 1.4mm aluminum to approx 3mm of pure copper.

Not sure if the XM-L on top of copper sinkpad and penny will have the space to fit under the aspheric lense, might need to go with a smaller shorter emitter…choice is yours…my above post I used a larger zoomie and it fit perfectly.

I also recommend putting some NOALOX on the threads (little dab will do you) and screw it down

Your pill already has the screwdriver tightening knotches cut in them so stick a small flat head in the groove and snug it down tight, then put the top cap back on

A 14500 on that driver acts as a 800mA linear regulator, the little guy will get WARM fast all over, in AA mode it acts as a 500~mA booster, usually won’t get that hot

With a big fat XM-L in there, it does throw quite a bit more light in flood mode, but the zoom is affected and throws a big ole square rather than a large image of the XP-E, you could always throw a XP-G or XP-G2 in there but with the penny heatsink the focal point is off and it won’t zoom crystal clear…it will now throw, but throw a round light rather than a perfect image of the emitter

hah…pays to re-read the thread…I posted dang near the same thing about 4 posts above…duh!

And yes, me and my son ended up getting impatient using the low torque harbor freight rotary tool, stuck it in my Porter Cable 18vdc drill and put it on high speed and WHOAH NELLY hang on to that sucker…I recommend Ultra Gray sensor safe RTV (Silicon has better thermal conductivity than epoxy)

Believe it or not the SK68 in AA mode doesn’t throw as much light, but with a fresh battery will run a little over an hour, with a Li Ion 14500 you will be lucky if it runs for 30-40min, ALOT more light, but ALOT more heat!

What 600 lumen flashlight did you win?

Simple fix, don’t run your $3 SK68 clone for more than a couple minutes on high with a 14500 battery.

Like other moderate and high power lights, the SK68 is a heat sink. That is why it is bigger than an SK58 which is much bigger than some lower powered AA lights. They do heat up fairly evenly.
Some have solid pills and some don’t. I just got some silicone heat sink compound for the slides of zoomies that slide on 0-rings. Some slide on wire rings, so the compound can be hydrocarbon based.

Thanks Rob. I can’t find the link to the Old lumens posts though? Haha Yeah I am looking forward to it getting here. War hawk it seems to be the same one Rob posted above.

Unknown 00101 thanks for suggesting the crooked emitter. So the hollow pill won’t matter? The light never got hot. Fritz t cat you seem to be saying the same. I hope so, then I can just use it.

War hawk that’s fine, your second post was more detailed so I could understand. Yeah I thought that looked like it’d fit in a drill :slight_smile: How do you braise, just melt solder on the stove and put it together?

How do I get the white plastic retainer back on for now? Now that I know I don’t need it with heatsink I can push harder. I probably don’t take it apart if it never breaks. Kinda worked out….

I tend to not worry about the state of the pill in tiny, inexpensive lights like the sk68.

The hollow pill will offer less thermal transfer from the emitter, causing the Led not to last as long as it would a properly built pill. The light output will be a bit less as well.

Oh ok . So it might be a good idea. If I upgrade I’d probably need one been looking through my change for heatsinks :slight_smile: Found a wheatie :slight_smile:

Definitely, that new emitter will probably cost more than the whole SK68. :smiley:

It probably helps to mention: I view my stock sk68’s as cheap lights to stash around the house. If one is lost I’m only out a few bucks. If I were to upgrade one then I would hoard it into my collection and do my best to get it in tip top shape with more mass in the pill, pop a penny in if it’s hollow, etc etc.