SD 301 dimmed

wingchun1274 · Feb 25, 2014

Hello all

Today I got my new LSON SD 301 from dx.com
After 2 hours of fun the battery was empty. So I changed it with another one which I am 100% sure is full and working. After I inserted the laser is dimmed. It lost more than 75% of its normal brightness. This case is identical to: http://laserpointerforums.com/f45/laser-doesnt-work-properly-73895.html

I have tried more than 5 batteries that are full and working with and without pcb. I tried dissambeli g the thing and assembling. No result. I tried clicking the button in every rythm I know. No result

Somebody familiar with this?

ru124t · Feb 25, 2014

My SD303 can only be run for approx. 2 minutes then has to be cooled down for about 5 minutes. It is basically the same laser. If you run it too long, you may cause damage to the diode! Hope this helps!

wingchun1274 · Feb 25, 2014

ru124t said:
My SD303 can only be run for approx. 2 minutes then has to be cooled down for about 5 minutes. It is basically the same laser. If you run it too long, you may cause damage to the diode! Hope this helps!

Well. Shit I definitely runned that laser more than 2 minutes. But why doe@ that laser heats up that fast? Cmon 2 minutes and after that half dead?

ru124t · Feb 25, 2014

I have also found that most of these ultrafire batteries have to be charged and ran down four or five times when new to get the best life from them. I know most on here say they are junk but from my very limited experience, I have found that they work way better after the fourth or fifth charge! Perhaps someone with more experience than myself could lend a hand on this phenomenon ! Maybe its just me but this has been the case with all four of the batteries I own.

wingchun1274 · Feb 25, 2014

ru124t said:
I have also found that most of these ultrafire batteries have to be charged and ran down four or five times when new to get the best life from them. I know most on here say they are junk but from my very limited experience, I have found that they work way better after the fourth or fifth charge! Perhaps someone with more experience than myself could lend a hand on this phenomenon ! Maybe its just me but this has been the case with all four of the batteries I own.

I agree that ultrafire is not junk. However I cant confirm that after 4 or 5 recharges they work better. If you are lucky it is possible to get a good quality 18650 battery made by ultrafire

ru124t · Feb 26, 2014

Sorry I could not be more help but I am sure some more knowledgeable member than myself can add to this discussion and help you!

Marco Polo · Feb 26, 2014

wingchun1274 said:
I agree that ultrafire is not junk. However I cant confirm that after 4 or 5 recharges they work better. If you are lucky it is possible to get a good quality 18650 battery made by ultrafire

WRONG! See the link in my signature to see EXACTLY why Ultrafire is complete trash. Your health and safety could depend on it!

If it's a 405nm laser then unforunately your diode has died. These units are prone to it. Some of them run forever without fail, others die within minutes. It's happened to me several times and with these violet 301's it is simply a tossup between what kind of unit you got.

ru124t · Feb 26, 2014

OMFG! I am going to buy some brand name cells as soon as you read this! THanks man I appreciate the heads up! Just purchased a nitecore I4 Intellicharger v2 and will definitely buy the aw or Panasonic cells to go with it!

RYDorDIE278 · Feb 26, 2014

Dont get people started on the ultrafire batterys.... Haha, personally i think a very small amount of ultrafire batterys are true ultrafire and perform quite average for cheapies but the other 90% are fakes, copys , refurbishes, so true ultrafires are alright but good luck finding the real ones! Anyway with your laser have you tried to test current draw from tailcap with a multimeter?

wingchun1274 · Feb 26, 2014

RYDorDIE278 said:
Dont get people started on the ultrafire batterys.... Haha, personally i think a very small amount of ultrafire batterys are true ultrafire and perform quite average for cheapies but the other 90% are fakes, copys , refurbishes, so true ultrafires are alright but good luck finding the real ones! Anyway with your laser have you tried to test current draw from tailcap with a multimeter?

I already ruled out that thr tailcap is the problem. I
Used a metal thing to connect the battery without the tailcap. So I think I killed the diode

cheech226 · Feb 27, 2014

wingchun1274 said:
Well. Shit I definitely runned that laser more than 2 minutes. But why doe@ that laser heats up that fast? Cmon 2 minutes and after that half dead?

like the others were saying, the 405 diodes are delicate. if you ran it longer than 2 minutes straight you probably killed it by overheating.

tttonyyy · Jan 13, 2015

Apologies for necro posting but there don't seem to be many threads on the subject. I have a dim 405nm 301 and I'm pretty sure it died from inadequate heatsinking -initially I thought it was due to this gap around the diode:

But further dismantling showed it is pressed into the metalwork behind it - however this part is electrically (and thermally) isolated from the rest of the case by a plastic sleeve. The 5.6mm diode is connect with case negative, and the host is case positive.

The tag above connects to the case and is the +ve feed from the 18650. This makes contact when the assembly is press-fitted into the host.

There is nowhere for the heat to go with this design - but I'm not sure how much heat is produced.

The diode has 5.5V across it when powered (from a single 18650), so it must be a boost driver. If I stick the diode across a bench supply, what should the current be limited to?

alessnilsen · Jan 14, 2015

I'll guess 100mA, if this laser was capable of burning, then the LD could be generated a considerable amount of heat, and this little heatsink may not have been enough. Never seen one assembled this way!

Use a dummy load to test the driver, and if it works, you will be able to know the output current, test the diode too, because it can be dead.

Isn't common a 405 be case negative, generally they are neutral.

tttonyyy · Jan 14, 2015

I've run it up on a bench supply and worked up from 80mA to 180mA. The peak fluorescence against white printer paper is at about 130mA beyond which it dims (wavelength changes with current?), but it's nowhere near as bright as it should be, so sadly it's toast.

If the case can float or be +ve I wonder why they connected it to -ve? I'm tempted to check my other hosts don't have insulation around the diode and if they do swap the case to +ve and replace the plastic insulator with a copper shim.

alessnilsen · Jan 14, 2015

I've run it up on a bench supply and worked up from 80mA to 180mA. The peak fluorescence against white printer paper is at about 130mA beyond which it dims (wavelength changes with current?), but it's nowhere near as bright as it should be, so sadly it's toast.

Yes, sadly, seems that your diode are really toasted, now it is a very inefficient LED, what explains why it dims when you increase the current.

If the case can float or be +ve I wonder why they connected it to -ve? I'm tempted to check my other hosts don't have insulation around the diode and if they do swap the case to +ve and replace the plastic insulator with a copper shim.

Can be that this LD is a case negative, here are the two common types:

You can find it by trial and error, since the positive is always the same pin, this will determine if this plastic insulation could be removed. Your driver, by your pics, are a generic boost driver, designed for neutral LD's, so will be easy to find a replacement diode for it.

Did you tested the driver? We need know the output current that it supply, in order to find another suitable diode for it. To test, connect a 1 Ohm 1W resistor directly in the output of the driver and power it with a fully charged battery, then measure the tension across the resistor, this will be the output current.

If you don't have a 1 Ohm resistor, you can use another value, the formula will be: I=V/R. For example, if you measure 400mV (0,4V) across a 1,5 Ohms resistor, then, 0,4/1,5 will give 266mA of output current.

tttonyyy · Jan 15, 2015

Thanks for the info, it's the lower one of the two shown above.

With a 2R2 load, current starts at 180mA and creeps up to 205mA where I stopped as a diode on the driver board was getting too hot to touch.

I tried the same with a 4R4 load and it started at 160mA and crept up to 190mA (again, hot diode).

I'm not sure the load is representative, if I remember rightly from my power supply design days having the output voltage of a boost circuit below the input voltage just ***** current through the flyback inductor and series diode which seems to be happening here. So I'll grab a few diodes and build something with a forward voltage closer to the actual load.

SD 301 dimmed

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