Killed an A-140 and M-140 with Flexmod P3... should I get a new hobby?

So a while ago I purchased one of DTR's 1.75 watt A-140 based lasers pre-assembled to resemble a lab style laser. However I made the foolish mistake of assuming that this meant it could be left running indefinitely (diode was mounted in heatsink and was air cooled) but evedently I was wrong I soon had a 100 mW zombie diode.

I decided I'd try and replace the diode however by this stage while fiddling with the zombie A-140 I'd managed to completely change every pot on the Flexmod P3 to random/unknown values.

Then I built a dummy load to try and get the flexmod back to some reasonable settings... but then I realised I didn't understand the point of the dummy load (how many diodes should you set the jumper to?) and rage quit (mostly due to the 90% humidity / 30 deg C weather here), and so I followed the flexmod manual: hook its output to a DMM to 'directly' measure the output.

Long story short the new shiney $99 M-140 arrives with G-2 Lens and after much paranoia I hook it up to the flexmod at low current output setting and hope it doesn't immediately release a puff of smoke. I manage to get it to lase and I run it up to about 1.5 watts output as measured on a LaserBee 2 which was drawing less than 1500 mA current so I assumed I could push it more, but sure enough I then look over to see my other DMM reading 5.0 v across the diode. After a heart attack (I assume the M-140 shouldn't ever exceed 4.7 V max?) I turn off the power but by then I discover I have made myself yet another zombie (which now puts out a incredible 5 mW or less).

In any case I think if I try another diode again it will be with a different driver: I don't really understand how the output / tuning of this driver works. For example increasing the amps output also increases the voltage... so what if you reach 4.6 volts and the diode is still only putting out 3/4ths its supposed safe maximum (2 W)? Are you supposed to exceed 4.6 V?

I think once I stop being a postgraduate student and 'get a real job' I'll just drop $500+ on some Aussie forum member to make me a portable 2W blue. (Battery power lasers >1mW cannot be imported into my photon-phobic country).

My stupidly big heatsink:
http://i.imgur.com/JUoI3pU.jpg

The terribly soldered but apparently electrically sound dummy load:
http://i.imgur.com/QFVXCpn.jpg

Zombie spot:
http://i.imgur.com/2jOGih4.jpg

Zombie spot:
http://i.imgur.com/D57RX3K.jpg

Why not just buy a mohgasm linear driver or ben boost mini, pots are not good at all IMO, 1W-2W lasers can be had for ~$100-$200

Have a look at this http://laserpointerforums.com/f39/sale-new-1w-2w-445nm-501b-lasers-110-a-78452.html

Those are very nice units but they would almost certainly be confiscated by customs as they exceed 1 mW. They have become quite proficient at finding them (presumably by x-ray). Then again at roughly $200 each I could take a chance twice and probably still be better off than I've been with my described failures...

There's no limit voltage wise as to how much a diode can handle... That's why we use constant current drivers, as they adjust the voltage for us to get a specific current through it. There is a rough current limit however!

As to what happened to your diodes, well, a number of different things could have happened...

The diode could have been shorted out, and then unshorted resulting in a capacitor hitting it with too much current, causing it to go "poof".

The Flexmod itself could be to blame, however I do not know for certain.

M-140 diodes can handle about 1.5-1.75 amps safely. Over that you start to run into the realm of the uncertain and your diode may blow out or LED after that. That may have been very well what happened to your diode.

As to why your diode might've not given you your 2 watt output, well, all diodes, and I mean all diodes are never the same. Some give more light output per power input, some less. Yours might not have been super efficient, judging from the fact you were using G-2 lens, and putting 1500 mA or so in it.

What I'd suggest you do, is to get a 9 mm 445 nm diode as a replacement for your M-140. They can handle a lot more current and power output so you may have slightly more luck getting one of those to work too. I'd also maybe put the flexmod you have now aside, and try and use a different driver of whatever kind you'd like.

And also, don't get discouraged with it. I've had a few lasers fail on me too, be it due to stupidity, or just, for no apparent reason whatsoever. You just gotta take it slowly, and if you need help, ask away. There are a lot of good posts on here that can help you out with lasers and building them.

Eye said:

Those are very nice units but they would almost certainly be confiscated by customs as they exceed 1 mW. They have become quite proficient at finding them (presumably by x-ray). Then again at roughly $200 each I could take a chance twice and probably still be better off than I've been with my described failures...

Click to expand...

If you hadn't noticed I live in Australia and I have two of those lasers, all you need to do is post the module and heatsink seperately to the host, which this seller will gladly do, just remember double postage is not free, its an extra ~$15 or so, so its ~$30 for postage to Australia which takes a little over 1 week to arrive.

Le Quack said:

There's no limit voltage wise as to how much a diode can handle... That's why we use constant current drivers, as they adjust the voltage for us to get a specific current through it. There is a rough current limit however!

Click to expand...

I always assumed that at any given voltage the diode would essentially act almost like a short circuit and try to pull as many amps through itself as it could, and that this was the reason that CC drivers were needed. I find it hard to believe that any semiconducting device can have no voltage limit. :thinking:

Eye said:

I always assumed that at any given voltage the diode would essentially act almost like a short circuit and try to pull as many amps through itself as it could, and that this was the reason that CC drivers were needed. I find it hard to believe that any semiconducting device can have no voltage limit. :thinking:

Click to expand...

What le quack said is correct I even had M-140 diodes @ 5.5V it differs per diode and at what current you run them. I killed 5 or more diodes so don't sweat it. And yes you can run your diodes for hours straight in your heatsink only at LOW current.

greetings,,

Diodes have Internal Resistance and this resistance changes with the temperature of the diode
The Voltage depends on the internal Resistance and the current you can put 7V on an M140 if the current is limited the driver will automatically reduce the voltage to exact the level the diodes needs depending on the internal resistance and the current setting !

I suggest you another driver, test the driver with a dummy load and an DMM, short the output leads of the driver before you connect the diode, make solid soldered connection no clamps and finally take ESD Precautions !

Edit:
And always turn the laser off by shutting the input voltage on the driver down ! and leave the diode connected to the output of the driver that will prevent spikes !

Nice heatsink! What's the runtime? 15 years? lol

Jokes aside, if it doesn't overheat in 15 minutes, it's not going to overheat.