broken DX 30 - diagnosis please?

Me mate sold me his broken DX 30 today for £6. He apparently wanted to pot mod it but somehow botched it. If you ask me, it looks like it was a pretty clean job, seeing as the black finish is without a scratch, the only notible damage are a couple little scratches on the cap. He tells me that once apart, he turned the pot setting in about 20 degrees or so and then tested to see if there was any improvement, but the laser didn't work so he figured, 'bugger, I'll order up another one'. Spare parts cant hurt (as I also have a DX 30) so I gladly gave over the £6, but I'm now wondering if the problem could be fixable.

When I press the button, I see a little red light being emitted behind the lens of the laser, sometimes when I press it, it will quickly flash green but then die down again. I've tried turning the pot down to where it would have been when it was made, but it's still the same dodgy deal.

I assume the diode is not burnt out, since it does come on at times, even if it is only for a moment.

So is this laser repairable, or is it only usable for parts?

Hi

I am not familiar with the dx 30, but as i see it, you could remove the laser diode and substitute a simple diode array or a similar light bulb (current/volt) wise. If you can manipulate the light bulb/diode array and see correct current / voltages, then u may have a good driver with a bum laser diode, if not, then u may have a poor connection along the driver path or a bad part in the driver. If I was you, I would try to drive a light bulb with the internals and proceed that way. alternately you could just try to temp power up the diode with no driver, but if you over power it, then you really didn't troubleshoot anything unless it shines bright, but it could die as soon as you see it shine via a straight power source.

Good Luck
SN

Actually, if there's a red glow in there, its the crystals. I highly advise you not to look into it, as that dim red glow is around 150mW of 808nm IR and will fry your eyeballs just like 150mW of red.

Unfortunately it seems your crystals are dead.

How does a crystal "die".

Thank you for the suggestions

At second glance, I may have used the wrong wording in my first post.
I'm not particularly knowlagable about lasers and when I said 'diode' I may have meant something else.
There looks to be 3 elecrtodes, meaning it wouldn't be a diode, but now I'm getting into the area where I have a scarce clue what I'm talking about.

I was reading a few releted threads and found that this sort of problem could be caused by misallignment of crystals, but I really dont see how that would be possible, as all the glue on the main housing is still in place.

Is there anything that I would be able to measure with a multimeter where I should see voltage? maybe somewhere on those three prongs (when the bateries are connected and the button is being pressed)? If it can be salvaged that would be great, but I don't want to screw it up even more in the process.

BlueFusion said:

Actually, if there's a red glow in there, its the crystals. I highly advise you not to look into it, as that dim red glow is around 150mW of 808nm IR and will fry your eyeballs just like 150mW of red.

Unfortunately it seems your crystals are dead.

Click to expand...

Thanks for the warning. Would this IR show up as particularily bright in a digital camera?
Because I had my camera set up and I could only see a dim purplish glow being emitted, dimmer than what I see when holding a TV remote infront of the cam while pressing buttons.

If the crystals are dead, can they still temporarily emit a green beam for short periods? I ask because I can sometimes see a green spot on my wall while pressing the button.

I had a lower power DX that had a real slow start up, whilst mucking about with it I knocked the circuit board sideways and lost all output......

On investigation I discovered that one of the LD pins had come unsoldered. Close investigation with a jewlers loupe showed that the soldering of all the LD pins was awful, instead of silver it was grey...that shouted "dry joint"!

I resoldered the pins and hey presto a greenie that lights up, good and bright, at the touch of the button..... It may be worth having a go to see if it helps, oh and if it does help make sure you reglue the circuit board to keep it in place.

Regards rog8811

It might very well be fixable, or at least worth the effort. I'd look for a dodgy electrical connection (the switch, or between the circuit board and casing).

The problem with these things is that the doubling process is nonlinear optics, and a small drop in pump power can result in a very big drop in green output, even to the point where there is none. I've tried this on a DX20, just under 200 mA there is no green at all, at around 300 mA it's maxed out.

So, try to measure how much current it actually takes from the batteries. If its less than around 250 mA and/or fluctuates when you handle the laser, start looking for electrical problems.

...
Whatever you do, do not look into the barrel while trying to fix it. The dull-red 808nm IR usually comes out in a pretty broad beam, but the solid state laser at 1064 is invisible, better collimated, and just as dangerous.

I did notice a white flaking crust around the PD- and PD+ connections on the curcuit board, but I'm not sure if that's of any significance or not -

Looks like some sort of glue that has been removed at some point, shouldnt be any problem. The solder joints don't look that good, especially on the smaller resistors, but that is quite common nowadays since leadfree solder is often used.

Measure how much it draws from the battery and diagnose from there.

I had this same problem with my first DX 30. The flaking on the PD+/- is most likely glue, (the PD +/- is where the Wish Brand solder their IR filter when applicable). What happened to mine is when I twisted the laser out of the pen housing, the actual diode itself remained in place (the button prevents the laser from moving with the optics) and the crystal needed to be adjusted. I was able to get it back green, but the focus was never the same and the beam was never as clean again (had lots of distortion - spots and spackles around the dot). Once open these DX lasers, it is very complicated to get it back perfect because the build design is so poor quality. Before giving up (as I eventually did), try opening the brass fittings (use a lighter to heat the lock-tight in the threads) and be very careful not to get ANY of the lens dirty. Try breaking the glue and with a screwdriver tighten or loosen the crystal. Be aware, one of my DX 30's came with a loose diode. You might need to unsolder the diode, and screw it tight from behind and between the three prongs of the diode, then solder it back. I am no expert, but I believe that the crystal converts the 808nm IR diode to 532nm Green with the exact correct distance between the diode, and the crystal. Perhaps while removing the laser the diode itself changes distance from the crystal. Good luck, but I would just buy another laser. As you will see more and more in this forum, I am done with DX.

The device that emits the 808nm light is indeed a diode, not by design to be a diode but by consequence of its design to emit laser radiation.
The third pin is to do with a photodiode in the same enclosure, for measuring feedback optically.
And yes, the crystals can occasionally lase randomly.

What the hell do you mean, solder IR filter? You mean photodiode? An IR filter is the LAST thing that goes on the laser, between the last lens and the aperture. LOL...

A crystal can die either by being cracked by internal heat or having its coatings cooked off it.

Yeah, its your crystals. I have had numerous lasers do this to me, including a DX 30, DX 20 and a core. Usually its the result of burning the coatings off a crystal, but can also be misalingment of the crystals. I dunno what you can really do about this, since the crystals are hard to realign, but if the crystals are still OK, you could try realigning them. Either way you will gain alot of knowledge by opening it up....

Check out the photo of the DX Wish 5mw laser. See the orange and green wires? That is where the IR filter is soldered.

The 200mW is different then the 30mW, but the concept and build method is the same. I use a toothpick to apply super glue when ready for reassembly. Of coarse, if you get glue on the lens, it’s all over.  Good luck, but this should act more as a learning experience then anything else.  Aligning the crystal and collimators are always a challenge and a half.  Lots of trial and error, just remember, the more you mess with it, the more chance of the crystal, and collimator lens getting dirty.  

P.S.S. I AM DONE WITH DX! – Only good for 5mW or gifts – in my opinion.

Kinda offtopic, but with the last picture posted could you rip the driver board and the diode out of the housing quite easily?