Mitsubishi 300mW - Died at 1A?

[tsteele93]

Hey everyone.

I just got a Mitsubishi 300mW for my first 635nm build (was building it for sale) and I was under the impression that 99% of these diodes can handle 1A of current. Is this true? Right when I hit 1A, I got the dreaded dimming. I immediately lowered the power and it still lases, its just zombied now (is this normal for these too?). I was under the impression that these were as durable as the 445s when it comes to dimming, etc.?

Maybe I was just too ambitious with this diode?

What power supply are you using? Are you sure it is stable and not spiking?

 

[Wolfman29]

I am using my variable CC/CV lab PSU. I'm pretty damn sure it's not spiking

 

[Tech_Junkie]

What power supply are you using? Are you sure it is stable and not spiking?

Diodes blow all the time. We are pushing them waaaaaay beyond recommended current. We're just spoiled with the performance of the 445nm diodes.

Looks like daedal still lurks the forum occasionally. I wish he'd post again, seems like he was really bright.

 

[Wolfman29]

Yeah. This thread has essentially become a warning to those thinking that it is a good idea to push Mitsubishi diodes past 1A. While rhd has managed to consistently do it (HOW?), I wouldn't recommend it.

 

[Tech_Junkie]

He doesn't tell you how many he throws away. :shhh:

 

[Wolfman29]

If he really threw away that many, he wouldn't make any profit on the lasers that he sells on here...

 

[rhd]

Yeah. This thread has essentially become a warning to those thinking that it is a good idea to push Mitsubishi diodes past 1A. While rhd has managed to consistently do it (HOW?), I wouldn't recommend it.

That's crazy talk. While I'd love to be the only one with magic current-upping wizard dust, unfortunately, I have no such dust.

These diodes are just fine at 1A. And for the record, I generally drive these AT 1A (or a few mA more), not really "pushed past 1A". But regardless, there's really not a lot of risk in pushing them to 1A. In fact, I would go as far as to suggest that they can often handle quite a bit more.

He doesn't tell you how many he throws away. :shhh:

I think I've lost maybe 2 of these, and even that, wasn't current related.

Bottom line dude, you killed a diode. When I kill a diode, I usually blame myself before the diode. You can blame the 1A of current if that makes you feel better, but I think it's irresponsible to give people the impression that there's any "high probability of death" at 1A. There just frankly isn't.

 

[tsteele93]

I am using my variable CC/CV lab PSU. I'm pretty damn sure it's not spiking

Just checking, there is another thread about some of The EbAy power supplies not being stable.

That's crazy talk. While I'd love to be the only one with magic current-upping wizard dust, unfortunately, I have no such dust.

You should sell the dust!

 

[Wolfman29]

Wasn't meant to be a jab at you. But we can't honestly know how often we are just getting lucky or what, because we are way beyond the datasheet. Maybe I got a dud, like how the 445s sometimes will fail at 1.4A. But, conversely, it would make a lot of sense if there are just some good diodes out there and there are some standard ones. And while you may get lucky with a good diode, a standard diode may not be capable of handling the current, or may burn out.

I'm just not too certain. The power curve I obtained for my current (living) diode shows that the "peak" power would occur at around 800-900mA if extrapolated, and then start dropping out. I dunno though.

 

[rhd]

Just checking, there is another thread about some of he by power supplies not being stable.

I think he's using a home-built power supply.

Wasn't meant to be a jab at you. But we can't honestly know how often we are just getting lucky or what, because we are way beyond the datasheet. Maybe I got a dud, like how the 445s sometimes will fail at 1.4A. But, conversely, it would make a lot of sense if there are just some good diodes out there and there are some standard ones. And while you may get lucky with a good diode, a standard diode may not be capable of handling the current, or may burn out.

That's certainly not my experience. I've probably played with a few dozen of these diodes, and I'm always setting 1A. Never a problem, save for those couple diodes I've lost.

Not taking a jab at you either!

But maybe you didn't get a dud... maybe you just killed a diode? There's no shame in admitting that, it happens to the best of us!

 

[Wolfman29]

Naw, not using a home-built power supply. Using a Mastech, but it's never given me trouble before as long as you set the upper voltage, short the leads, etc. I have a whole list of protocol for diode testing on my wall and it never fails me.

I went over my procedure over and over after the diode dimmed and I didn't do anything wrong - there were test leads soldered to it and isolated from one another for solid connections, I had it in a bulky heatsink sitting above a refrigerated ice pack to keep it cool (poor man's TEC!), and I slowly turned up the current until it just touched 1A. So if I did kill the diode, I should probably change my protocol? :thinking:

 

[DTR]

Naw, not using a home-built power supply. Using a Mastech, but it's never given me trouble before as long as you set the upper voltage, short the leads, etc. I have a whole list of protocol for diode testing on my wall and it never fails me.

I went over my procedure over and over after the diode dimmed and I didn't do anything wrong - there were test leads soldered to it and isolated from one another for solid connections, I had it in a bulky heatsink sitting above a refrigerated ice pack to keep it cool (poor man's TEC!), and I slowly turned up the current until it just touched 1A. So if I did kill the diode, I should probably change my protocol? :thinking:

What voltage are you setting the power supply to before connecting it to the diode? Also the current is set to zero when you first fire it up?

 

[Wolfman29]

For this diode, I believe I set it to either 2.6V or 2.7V as an upper limit. And yes, I *always* ramp up current when first testing a diode =p

The reason I like these Mastech PSUs is that you can set the voltage to essentially be overcurrent protection =p

 

[DTR]

For this diode, I believe I set it to either 2.6V or 2.7V as an upper limit. And yes, I *always* ramp up current when first testing a diode =p

The reason I like these Mastech PSUs is that you can set the voltage to essentially be overcurrent protection =p

Ok so you are saying with the unit on you slowly turned up the current and the diode was lasing strong until you got to 1A and it LEDed or it was dim right off the bat when you turned on the power supply?

 

[Wolfman29]

It was lasing strong until I hit 1A :\

 

[LaserCo]

Re: Mitsubishi 300mW - Died at 1A? (One person may not understand this!)

Naw, not using a home-built power supply. Using a Mastech, but it's never given me trouble before as long as you set the upper voltage, short the leads, etc. I have a whole list of protocol for diode testing on my wall and it never fails me.

I went over my procedure over and over after the diode dimmed and I didn't do anything wrong - there were test leads soldered to it and isolated from one another for solid connections, I had it in a bulky heatsink sitting above a refrigerated ice pack to keep it cool (poor man's TEC!), and I slowly turned up the current until it just touched 1A. So if I did kill the diode, I should probably change my protocol? :thinking:

I see a similarity with you also cooling your diode off in advance to an experience of mine.
Over in another thread:
(LINK) http://laserpointerforums.com/f50/de-canned-635nm-diode-adult-language-71241.html#post1026787

I had said:

I was running my 300mw at 946mA thru one of Moh's drivers/C6's, I was outside with it in the cold & taking photoes, ran it for probably 4 minutes, it was not even warm to the touch, before I stepped out I had put it in the freezer for a bit

upon returning inside I fired her up again and the beam went from bright to dim, not real dim but dimmer I tried it again in around ten minutes and the same thing happened.


Add that bit of info into the recipe!

It did not occur to me at the time I posted what's above but later when I did recall what I am going to add now it did seem that it may be related.

I was asked by someone to test out a 635nm/300mW diode with a ca$s$hio original 445nm collimation lens. Has anyone else tried this?
Though my testing was short, it seemed to look BETTER than with a 404/445nm glass half thread.
I then replaced that lens with a glass, for red lens and decided to go out and take beamshots.
(Oh...^^ Did that make sense?! some !%!$# has told me that I am hard to understand and asked me if other people have told me so!. (the conversation was as simple as 2+2))

1) could the cashio lens that apears to be with no AR coating had created some COD?
or
2) could PREcooling have some adverse effect?

or both!?