Black Weekend. I lost three 445 diodes!

I'm devastated!

Loosing a laser is like loosing a child. It feels like I lost my entire family is a plane crash this weekend...

I now know what caused it...but I still don't know why

The short verison:

Saturday I embedded my 2-3 watt(PBS) home-built lab build laser into my laser system. Spend hours aligning the dichroic mirrors. Hooked up the Flexmod modulation to my Medialas Mamba Black laser hardware/software. 0v = 0.01A 5v=1.2A (well within spec.)
Both lasers died after about 10 seconds of modulation. !!!

Ok, So I thought it must the power supply. So I installed a new commercial regulated PSU. Installed my 1 Watt TEC lab style. Spend Sunday with alignment. (Laser was running for hours during this process @ 1.5A).
Hooked it up to my German hardware/software as stated above.

Less than 20 seconds laser dead!!!!!!

The modulation is killing them and I don't know why. The Flexmod? Can these 445 be modulated?









UPDATE: 20 FEB 2011

My two new Flexmod P3 have arrived and sitting in customs. Should have it before the weekend.

Going to try modulate another 445nm and hopefully it doesn't kill it. Will post results....

Could there be a large enough spike when the modulation goes from 0 to 1.2a to eventually fry the little guys?

damn!! hope that does not happen to me- I plan similar and have mamba too- Id freak!! P3 as well- sorry for you--RIP little diodes RIP.

Hak maybe you should test everything with some LOCs or PHRs

Well thats what I would do. 0.02

MM that kind of sucks if it's the Flexmod, because you probably have no way of knowing if it will kill your little beauties until it does!

I've seen rumors on PL that the new flexmods could possibly be killing diodes.

See here: Flexmod's killing them

Coherent Light said:

Could there be a large enough spike when the modulation goes from 0 to 1.2a to eventually fry the little guys?

Click to expand...

It would go from 0-1.2A extreemly quickly........I wouldn't have guess this as it's "still within its current limit"

From PL it seems They are suggesting it can output the total amount of current available from the PS. At least I took it that way. If the Flexmod is bad.

That's true MM I didn't considered what the projector subjects them too.

Keep in mind these diodes are run at high pulsed currents in the projector anyway so they should be able to handle modulation.

I agree with you MarioMaster....

So must I accept that the modulation from the Flexmod caused the premature death?

I was using the older type Flexmod. I see there is a "new" type selling on ebay now for $39....I'm tempted.

Is there another possible driver anyone knows of that works well. It must have TTL/analog modulaiton

If you're in the DIY, you can try to build a sink or source driver with a current limiter on the modulation input (one as example is in my album), and test it first with a dummy load and an oscilloscope, for check if it work good ..... also, as safe process, is always good to check also the input signals (from the hardware to the drivers, i mean), for check that they don't have spikes in them.

You ned a fast scope, anyway, able to detect short-time spikes too ..... anyway, as principle, i doubt that the pure modulation may have killed the diodes, they works normally driven in PWM around 120Hz, on the projectors.

MarioMaster said:

I've seen rumors on PL that the new flexmods could possibly be killing diodes.

See here: Flexmod's killing them

Click to expand...

You know, it's funny you should mention that..

I've had issues with my Flexmod P3s killing diodes, but I'm not 100% sure that it's an issue with the Flexmod or not. I've put mine on my scope and I always see a very small voltage/current spike on power up, but the current always ramps up nice and smooth under modulation, no spikes there. The initial spike *could* be causing premature degradation, but it's not a very big spike so I don't know for sure. One thing I do know is that I miss the old Flexmod N2. I live by the philosophy "if it ain't broke, don't fix it", and I think that it applies to these new Flexmods. They supply less current, and would appear to *possibly* be hard on diodes.. not a win IMO.

It seems that MANY people are having issues getting support from drlava lately, whether it's in the form of communication or repairs. I've had 2 orders waiting to be shipped for quite some time now.. I'm not sure what the deal is there, but I really hope we can get some closure on this issue soon.

Also, when modulating diodes it is usually a bad idea to go from 0mA to full current. Laser diodes prefer to be modulated between a low current (standby) and high current setting. In my 445nm modules I set the standby current at 40mA and full current at 1A.

ElektroFreak could you not install a filter cap on the output just to be on the safe side?

Sure you could, but that should already be there.. according to drlava there is plenty of transient protection built into the driver. If that's the case then nothing further should need to be done except add a lasorb.. and that shouldn't even really be necessary if the driver is built well enough.

In other words, if the user needs to add more transient protection, that should be in the manual for the device. Typically when buying a driver one assumes that the driver is complete.

That's true, and I hope someone can isolate the root cause. I did find an add somewhere for a LM317 driver that if you read the fine print it shows you're getting the PARTS to build the driver.:thinking:

To properly analyze problems like these you need a scope to see whats actually going on with the current to the diode.

I could have a look on the scope if you could send over the hardware involved and any software you are using to drive it. I'm based in europe though, so if you are in the US it would probably be easier to find someone within the country to check.

Benm said:

To properly analyze problems like these you need a scope to see whats actually going on with the current to the diode.

I could have a look on the scope if you could send over the hardware involved and any software you are using to drive it. I'm based in europe though, so if you are in the US it would probably be easier to find someone within the country to check.

Click to expand...

Thanks for that....problem is that I live in the other hemisphere...in South Africa.

Just for the record I was using the old type Flexmod. I purchased it about 2 years ago. I thought buying the new type would solve my problem..perhaps I should try a different driver.

Could anyone assist me in a purchasing the right driver that does modulation and doesnt pop 445s?

Thanks all for the feedback