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FrozenGate by Avery

Is this diode dead...or is it something else?

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bug1124

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Aug 27, 2010
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Hi all,

I am hoping for some troubleshooting insight on one of my recent builds. I am running a 445nm A140 diode from a microboost controller in a 18650 powered host. After I finished construction everything was working properly. I ended up selling the entire laser to a friend. After about a week he said it would no longer turn on (no led, nothing). He sent it back to me and I found a broken + wire between the diode and controller. I suspect it broke when he adjusted the controller output pot. Anyway, I reattached the wire and still cannot get anything from the diode. I checked the power at the controller's output and found 13v.

My question is: Will a dead diode have no output at all or do they always do the LED thing? Or could this be a controller problem? 13v is high but does that come down when loaded? Below are some additional observations that may or may not help the experts...

Noticed some corrosion on the negative diode leg.
Diode legs were twisted and possibly touched at some point.

Thanks in advance! :)
 





Coherent Light said:
13v your diode is dead and buried....:can:
Click to expand...

Ok Good...well not good but at least I know for sure. I have already ordered a replacement, then started second guessing if that was the actual problem.

So it is possible for a diode to not LED. Learned something new!
 
Yes they can bite the big one without going led at all. Truth be told I've only had 1 out of 10 or so go led the rest just plain ass died.

The A140 Diodes only take ~4.5v so 13v is way way too much.

If You have any other problems just ask....Make sure to short the Capacitors before you solder your new diode.

Check your driver with a testload before hooking up your diode as well!!!!
 
lol, my 250mW red which I killed a while back, that went all LED on me, and it took the driver with it. At least I know why it died now, it was 250mW pulsed power and 150CW I thought it was 250CW. Ill be fixing it soon with a new flex drive, and a LOC diode. I might want a new host though, coz my current one only uses 2xAA which last for a matter of minutes. I want a 18650 host, but I dont know if my friend can make heatsinks for me for an aurora host
 
Thats interesting, the only other diode that I have killed was a red and it LEDed too. Probably something to do with red diode design that make them more prone to that.

My host is actually an Aurora that I machined my own heatsink for. It was fun to buy a cheap lathe and make every part of the laser myself. However, with the abundance of cheap pre-made heatsink options for sale on LPF I think I will just save myself the trouble in the future.
 
Doing the whole build on your own has a very satisfying feel to it. I would do everything on My builds if I still had access to a machine shop.
 
I don't know how the microboost work, but I would guess those 13V would go down under load.
I suspect you killed it when you reattached the wire without shorting + and - together.
Cap discharge --> POOF.
Does the microboost have a capacitor? I don't know...

Of course it might have been killed by your friend, or when it got all twisted up.
 
The voltage indeed goes down under load, that's how a current source works. The cap discharge is a candidate to kill the diode, but that will only LED it.

I'd say test the diode and driver separately, some drivers blow when they have no load, but I'm not sure which.
 
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