Can't get SLD323X-421 diode to light

[Coherent Thought]

I bought a couple of these, mainly to practice pressing and soldering but for the life of me I can't coax a photon out of them.

Bought them from Laserlands on Ebay.

I can't find a datasheet on these for the pinout, so I'm guessing it's the same as other 405's. Positive on the right, negative on the left, case in the center.
I've applied the recommended voltage and current with my bench PS. Interesting thing is after setting the voltage and hooking up the leads, as I ramp up the current the voltage increases, but not the current. It reads zero no matter what.
I've searched for any info on these diodes but haven't found what I'm doing wrong.
Any help is appreciated.

 

[bloompyle]

With the middle pin centered on the right side of the diode. Top pin is positive, bottom pin is negative. Pin to the center-right is the case pin.

 

[IsaacT]

Someone can correct me if I am wrong, but if your PS is increasing voltage but not current, the diode may be blown and that is why it isn't drawing voltage? I feel like I read that somewhere.

BTW, I like your name. It has been my Call of Duty username for a few years and I almost had my username changed on here but figured I would stick with WBS. Had it for too long lol.

 

[daguin]

The diodes are also susceptible to ESD

In addition, does your bench PSU rapidly discharge its load
A current spike upon connection could blow the diode

Peace,
dave

 

[Cyparagon]

Here's how you should be doing this:

1) Set voltage and current at zero. Do this BEFORE making OR breaking connections.
2) Connect the diode and be sure all connections are solid.
3) Triple-check polarity at all relevant connections.
4) Raise the voltage setpoint to 7V+. The readout will not change much (or might even stay at zero) and that is expected. So you have to go by feel - you'll get the hang of it eventually. When in doubt, just set it at max.
5) You are now ready, and the current adjust will work as intended. If it doesn't, either your supply is blown or you have not followed these steps properly. Diodes do not usually fail open-circuity, unless you were especially mean to them.

 

[jander6442]

Here's how you should be doing this:

1) Set voltage and current at zero. Do this BEFORE making OR breaking connections.
2) Connect the diode and be sure all connections are solid.
3) Triple-check polarity at all relevant connections.
4) Raise the voltage setpoint to 7V+. The readout will not change much (or might even stay at zero) and that is expected. So you have to go by feel - you'll get the hang of it eventually. When in doubt, just set it at max.
5) You are now ready, and the current adjust will work as intended. If it doesn't, either your supply is blown or you have not followed these steps properly. Diodes do not usually fail open-circuity, unless you were especially mean to them.

With the PSU turned off you should short out the leads attach the diode then with the dial preset to zero power the unit up and then slowly raise the voltage to set waypoint.

 

[Cyparagon]

If the voltage is set at zero, the voltage output will be at or near zero. The filter cap on the output always has a bleed resistor. There's no need to short the leads first.

Some cheaper supplies spike voltage on startup, so it's actually better in many cases to have the unit powered on before making connections.

 

[Coherent Thought]

First off I want to thank all who have responded.
I've been reading your posts here on LPF and have learned a lot. You all know your stuff and then some. :bowdown:
I apologize for not responding earlier, but I've been crazy busy at work.
I use the same bench PSU that you see in DTR's YT vids and follow his recommendations on lighting up the 445nm diodes he sells.
Start with nothing connected to the PS, turn it on and turn the current to zero.
Set it to the recommended voltage for the diode and turn it off.
Short the leads, then connect the diode.
Turn the PS on and adjust the current.
I've only burned two 445s so far. Learned about cheap drivers the hard way.
I don't have a ESD mat, but I do have a ESD soldering station, and wear a grounded wrist strap. Got it when I was building 386's. Yeah I just aged myself.
I'll keep trying this weekend, but I'm not going to lose sleep over these diodes.
I'm enjoying building my lasers almost as much as burning things with them. The press/puller Flaminpyro sells works great on these and I've found a nice pair of grooved tipped forceps to hold and heatsink the leads when soldering.

 

[Cyparagon]

If you expect your diode's voltage to be at, say, 4.5V, you cannot set your supply voltage at 4.5V. The two main reasons being voltage drop on the leads, and variation on exact diode specs. You can follow DTR's instructions if you insist, but your voltage setpoint needs to be higher than your expected voltage. Sometimes by several volts if you've got chinese leads.

 

[xirrious]

I hope im asking those questions next week. Goodluck man hope you grt your diode lasing. Id agree with setting voltAge over what the diode is expected to use as poor circuitry and wiring can add resistance and does in fact

 

[Coherent Thought]

I hate giving up, but I know my limits. Doubt that I have two bad diodes, but rather that I got them too hot soldering, or popped them on the PS. Think I'll stick with diodes from DTR. Never had a lick of trouble with his stuff.
Thanks again for all your help. :beer: