DVD RW laser die... HELP!

[Farhankhosravi]

Hi
I had a dvd rw laser, with ~300mw power
And to extend lifetime, I drive it with 240ma supply (with common lm317 constant current circuit)
I tested my driver very well in very high and low temperatures by multimeter, and it was constant on 240ma. So driver works well..

I used laser to engrave for ~3 hours without any problem, and laser wasn't even get warm!!... It was lasing perfectly.
But today, when i was focusing, i just touched lm317's metal body (heatsink place) and then my laser turned to an LED!!!
Now Light is very low and not engraving anything...

It's clear that my LD id dead now, but WHY???
Is Static electricity goes through lm317's body to laser and makes it die??
Is that possible?? Or problem is somewhere else?...


(Note: i am using a metal laser case, and i figured out that case body is directly connected to laser's gnd pin!.. so it's connected to laser heatsink too..)

 

[gazer101]

Not so sure running it at 240mA would do much in the way of extending lifetime since most DVD RW reds are made to run under 200mA at most

But besides that not having a capacitor in the circuit or a defective laser could be the culprit

 

[Farhankhosravi]

Not so sure running it at 240mA would do much in the way of extending lifetime since most DVD RW reds are made to run under 200mA at most

But besides that not having a capacitor in the circuit or a defective laser could be the culprit

Thank you.
Yes, there is a 10uF capacitor parallel with LD.
I just need to know that static electricity would go through lm317 body or not....

And as i saw in lot's of websites, DVD LD current was 270~350ma ! And my laser doesn't even get warm...

 

[Farhankhosravi]

*UPDATE*
This is driver schematic:

 

[Farhankhosravi]

Nobody knows what's matter??... I have just 1 laser left and don't want to loose it in same way..

 

[FireMyLaser]

Any part of the circuit that's not ground is vulnerable to ESD, so yes it can happen again. Also switching the power on the ground side may not be the best idea. I would use a PNP or P-mosfet on +Vin at the 17Ohm resistor instead, but it's unclear if this was the reason of the failure.