LD driver configuring questions

[VDX]

... had some wrecked blue diodes "died" with overcurrent spikes - could be the bond wires are evaporated, so no contact and no current through the diode.

You can look with a microscope or good magnifying glass through the emitter window to see, if the wires are intact or not ...

Viktor

[jors]

I got similar issue. I always test driver with a dummy load before. However and despite lot of precautions, the driver failed and delivered 8A! thru 3x 9mm 445 diodes in series (was working good with dummy before!!!). Result: 3 lasorb damaged (crossed) and magic smoke in one. 3 blues instantly killed...bond wires evaporated for sure, no more current thru them... and no 'led' glow this time... ouch!!!
Also killed 4 reds some weeks ago...WTF!
maybe we could open a new thread "RIP diodes" to confort altogether with those bad experiences hahahaha

... had some wrecked blue diodes "died" with overcurrent spikes - could be the bond wires are evaporated, so no contact and no current through the diode.

You can look with a microscope or good magnifying glass through the emitter window to see, if the wires are intact or not ...

Viktor

[Maltes]

Dunno why I didnt just test the diode for short circuit. There is none. When the multimeter shows voltage jumping from around 0 to 12.5 that's the from the diode power pins of the driver. d'oh

[VDX]

... for this diodes with burnt bond wires - if you're good with micro-handling, then it's worth to open the can housing and then bend and solder the bond wires together again ... could so "reanimate" some of the diodes

Viktor

[catalanjo]

Viktor ...apart from you (the eternal optimist), I think I could count on one hand, the PL members, capable of what you call (micro-handling), so I think Maltes best bet, would be to just determine (as far as possible), cause of death, and organize an elegant funeral.

@ Jors "RIP diodes" thread ...great idea ... why not go ahead and do it?

@ Maltes
"Dunno why I didnt just test the diode for short circuit" ......you did!......the current test, is exactly the same thing .... but with a decent voltage source, .... probably capable of driving some current through a badly soldered connection unlike the meter!
When you "test for short circuit", the ballast (series) resistor and PSU, are just connected inside the meter which just measures the voltage drop, ......although some cheap multimeters only have a little 3vdc battery supply and would have shown sweet FA ...even with a blue diode working.

Cheers

[Maltes]

Yeah, I rather spend $35 and get a new one from techood than try to solder a microscopic wire.

[catalanjo]

Maybe U could send the dead fella to Viktor for microscopic post-mortem and maybe even an "arterial transplant" ....
Cheers

[VDX]

... could be a good idea indeed

Attached are images of two other IR-laserdiodes (1x = 9W@975nm, 3x =25W@975nm) I've opened to get the "feeling", how to clamp a fiber to the emitter - will do this with some 445nm-diodes too ...

Viktor

[VDX]

... so -- found one of the old overdriven 2W-diodes, opened the can with a file and made a fast macro image with a web-cam.

You can see the 4 "evaporated" bond wires on the left side:



Viktor

[catalanjo]

Wow ! ... fantastic stuff ....am I right in thinking that this was definitetly due to being over-driven and NOT due to ESD?
Cheers
PS. Are you actually going to attempt to re-solder it ? Bare in mind that gold actually conducts a lot better than solder !