Help, please! Problem with 9mm diode build

[Jstr]

Hi, I have no idea what the problem is with my build, so if anyone has experienced something similar, please help me out. Thank you in advance.

Here's what's happening. I am using a rectangular blitzbuck driver and standard 9mm diode. So I connected the driver to the battery tube of my host and set the current no problem, but when I hooked up the diode and turn it on, the diode flashes once very quickly then goes dark. No clue why this happens, but after, I tried again with my test load, and got a very stable 2.4 amps. But it does not work with the diode. I also tried a reduced current.

It does not seem to be a problem with the driver because it works with the test load, but I do not know how the diode could do this.

I want another opinion before I try another diode or maybe I would be better off trying another driver?

Here is a pic of my setup:

Any ideas on what to try?

 

[rhd]

Hi, I have no idea what the problem is with my build, so if anyone has experienced something similar, please help me out. Thank you in advance.

Here's what's happening. I am using a rectangular blitzbuck driver and standard 9mm diode. So I connected the driver to the battery tube of my host and set the current no problem, but when I hooked up the diode and turn it on, the diode flashes once very quickly then goes dark. No clue why this happens, but after, I tried again with my test load, and got a very stable 2.4 amps. But it does not work with the diode. I also tried a reduced current.

It does not seem to be a problem with the driver because it works with the test load, but I do not know how the diode could do this.

I want another opinion before I try another diode or maybe I would be better off trying another driver?

Here is a pic of my setup:

Any ideas on what to try?

Sad to say it, but this sounds like the behavior of an LD that has gone LED to me.

Can't speak to the reason, but if you really want to rule out driver, give an XDrive a shot. I think DTR sells diodes already paired with XDrives.

 

[Hemlock_Mike]

Connect the LD your CC/CV power supply set to
a MAX of say 1 Amp and about 4 volts.
Slowly bring up the voltage until it goes into
CC and watch the laser. Report the readings.
HMike

 

[Jstr]

Thanks guys for the quick replies!

I really don't think (at least i hope) the diode is LED because I can see the beam very clearly and focus it to a point. It just doesn't stay on for longer than a tenth of a second!

I do not have a variable power supply yet, so I may try a 2.4 A xdrive, see if that works. Brb

 

[rhd]

Thanks guys for the quick replies!

I really don't think (at least i hope) the diode is LED because I can see the beam very clearly and focus it to a point. It just doesn't stay on for longer than a tenth of a second!

LED'd laser diodes do that.

 

[Jstr]

Okay, well it has probably gone LED then. Darn...

 

[rhd]

Okay, well it has probably gone LED then. Darn...

If you don't have a bench PSU or other variable CC power supply, then a 317 is your best friend. For ages I relied on a 5 ohm pot and a 317 (maybe 1085?) for a lot of testing work. It's worth grabbing those parts and giving the diode a test before you write it off.

(but it sounds like a LED diode)

 

[DTR]

Few things that can help diagnose it. Does it flash and go to nothing or a faint glow? Is the module getting warm and still producing no light? What is the current draw while attempting to power the diode? You can put your DMM in series with the batteries to test this.

 

[Jstr]

DTR, it flashes then absolutely nothing. No glow. Beam is visible for about a tenth of a sec.

The module does not get warm at all.

The current draw on batteries is only for the time the diode light up. The time span is not long enough for me to measure it, but the meter spikes up a little then goes back to zero.

I blew the IC on my last xdrive by mistake (anyone know how to replace/what the exact part is?), so I cannot test the diode yet.

Thank you for your help

 

[Jstr]

Update: pretty sure it is the driver.

I tried reducing the current way low like Mike suggested, and then the diode worked! Then I adjusted it back up in small increments as high as it would go without reverting to the flash-then off state.

Then I hooked it back up to the test load for the fourth time, with a slightly reduced current, and my meter reads 2.14 for about two seconds, then it drops to zero again.

Is there seems kind of built in protection that could be triggering and causing this? How can I tell/what if anything can I do about it? I would love to be able to drive my diode at full potential. Thanks guys!

 

[Cyparagon]

Might be a fractured solder joint. Those can cause all kinds of intermittent and thermally related problems. When you find it in a working state, try poking and tapping various parts on the board to see if you can get to fail that way. Inspect the driver under a microscope if possible. Or just reflow all the joints. Sometimes that fixes weird problems like this.

 

[crazyspaz]

Weird...All the round boards I have work flawlessly, but those rectangulars sure are being a buncha whores (excuse my terminology). Sam (creator of these drivers) changed some things from the old drivers, and I thought that the only change was the IC package- I have a feeling something else got mixed up. I don't know what else it could be- I triple check every solder joint on every board, and obviously test them all before selling them- but still crap like this happens. I am going to try making a few of the older design, see if those magically work for some reason.

In the meantime Jstrawn, I have refunded you for the driver. If the other one you bought doesn't work I will refund you for that too. I'm sorry this has been such a crapshoot for you man, I really am Anything I can do to help, please do ask!

 

[DTR]

Yea when you said it flashed and nothing that did not sound like a LED as they usually glow and produce a lot of heat.

With the rectangular blitzbucks in the past I was never able to get them to stay in regulation driving a 445nm past 1.9A. Not sure if there were any changes but if not that could be the problem here. Jstrawn try setting it to say 1.8A and see how it works. Your test load may not be dropping the same voltage as the actual diode which is why it looks like it is doing 2.4A which was what confused me for a long time when I used to use them.

 

[Jstr]

Thank you very much, crazyspaz. You have been great to me. +rep if I can. I just have terrible luck with drivers. The shipping stuff was in no way your fault.

I will try out my second board now, hopefully that works.

DTR, that's interesting you say that, it seemed to run fine with the LD at 1.8A actually, but then with the test load, it wouldn't. I'm using an adjustable test load set to 4 diodes, is that right? I can test the actual voltage drop though. I think you are right about the different voltages.

 

[Jstr]

Well darn... The second board performed similarly but worse. I played with both for at least an hour, and I found something that might be interesting. To summarize: When I turn the pot all the way to its lowest point, I found that they both put out very stable currents around 1.4-1.5 Amps. One goes up to about 1.8A before it reverts to the behavior I described. The other only goes to about 1.6A. The weird part is on the border, my meter will show the current stable for a few seconds and then the driver simply shuts down, going straight to zero on my meter. I checked the temperature of the driver, but there was virtually no heat. Then, when I went above maybe halfway on the pot (for both drivers), the driver ceased to put out any current, meter read zero the whole time. I am not sure whether there was a spike and it was simply to fast for my meter to read or there was absolutely no current coming out.

So with this in mind, do you think it could be an issue with just the pot?

thank you guys! I really appreciate it!

 

[Jstr]

Okay, I'll do that tomorrow.