Dead BDR-209

[PCfreak]

Just received a BDR-209 in the mail today, awesome service from Jordan.
Purchased it for a cnc laser cutter project that I've been designing for weeks, ended up self destructing the diode in a power on test. Not really sure what went wrong :yabbem:

Power on test was done with a crude LM317 driver limited to 250ma and verified with a DMM across a diode bank. 12v bench supply -> LM317 -> 5ohm feedback to Adj. I didn't think to put filter caps on input/output.

- First attempt didn't fire the diode, the positive lead didn't have a solid connection.
- Second attempt the diode came on, but was pretty dim with a lot of halo (not sure if that's to be expected at 250ma)
- Third attempt I upped the current to 500ma (verified via DMM). Laser fired but wasn't much brighter, dimmed a bit more and then out.

Diode now measures 4ohms and sinks 500ma with no visible light.

I'm guessing by the second attempt the diode had turned LED. Seems like one (or all) of the following probably happened:
1. The bad initial connection caused an over voltage of the diode.
2. Power On Spike? - My bench supply isn't the cleanest (transformer based) fed into a LM317 with no input/output filter caps. I thought the LM317 would do a good enough job, maybe not. Diode was connected in circuit when the supply was switched on.
3. No slow start
4. ESD - I was wearing a grounding strap on a grounding pad at the time of the test, but I was not as careful during unboxing. I was careful not to touch the wires but...

I'll try again once I build a better driver (Sam's Laser FAQ - Diode Laser Power Supplies) and order a new diode.

 

[94Z28]

For that diode 250-500ma is a big jump when your already having issues at 250ma in my opinion; but I am not 100% of the max current. My LM317 takes 12v input to power my M140s and I use it for testing the diode modules I sell.

I wouldn't ever try it on a diode like this 405nm because they sound very finicky to me. I've read a lot of BDR209 dying.

Jordan will chime in on your issue but if it's not working at 500ma then it's probably dead. I would suggest neXT time around to buy a diode with a driver from DTR already setup if your unsure about setting one up..

 

[RedCowboy]

You may need a ramp up capacitor, the drivers DTR uses has them as well as other protections.

 

[PCfreak]

Thanks for the replies.
Any idea how long of a ramp up period is safe for this kind of diode? I'm hoping to be able to do TTL modulation with the driver. Not sure what frequency I should be shooting for. More for high resolution engraving.

I'll also interested in experimenting with analog modulation. Changing the power while in CW mode seems like it would give the appearance of a higher resolution.

 

[Alaskan]

I was going to say for a pointer, don't drive the diode harder than 800mw out, I had one putting out over 900mw and it died, and that was in a pointer, your application will probably push the diode much harder due to increased duty cycle, unless pulsed with enough time between pulses to give it some rest.

 

[Pman]

I would also suggest going with the so6j diode instead as in my opinion it is much more robust than the bdr209. I've blown plenty of bdr but not a single SOJ6 during testing or building.

 

[Exerd]

Bingo...

Number 2!!!

It's a more common mistake than you would think, and happens to the best of us. I was originally warned of it from a member here about 6 years ago, but sometimes I can forget things.

I've blown a 405nm 12X on a $400 lab supply once. Trust me, the price of the supply doesn't matter; turn it on with diode connected and be ready to start swearing.

A Cree XP-G2 is a durable LED, takes 6A of current easy--well I blew one of those by turning the supply on while connected and even was set at 0.0V when doing so. Just goes to show, never have anything connected at turn-on to a DC supply.

A great habit to get into would be clipping the alligator clips together when the supply is off, so you remember to turn it on when they are still clipped together.

 

[Alaskan]

Ha, I've blown more than one diode by turning the power supply on while connected to the terminals, spike!