Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



I think I goofed.

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
Hey all. I've been reading through the forums for the last few weeks, and started constructing my first laser. After a little bit of a mistake, I had it up and running!

And then it didn't.

I have a Survival Laser adjustable driver (read 1.73v on my multimeter with dummy load)

S4 Host

and the M 140 diode i ordered through DTR.

Now I'm pretty sure I went ahead and toasted the diode. Is there anyway to really tell if this is the case? I desoldered the diode, and reattached my dummy load, and it's still running at a rocksteady 1.7v.

The issue that I ran into while constructing was that apparently the SL driver is shipped at full power (2.3a) and the POT also is backwards (full Counter Clockwise is highest, full clockwise is lowest) so it overpowered the laser, where it laser'd but then dimmed. I did a bunch of reading, saw it must be a current issue, and bought the supplies to make a dummy load today, so I only turned the laser on about 5 times overpowered. I'm sure I'm an idiot in this circumstance, but I'm hopeful.

I'm sure I know the answer, but I figured I'd ask if anyone had any thoughts.


The oddest part is the laser didn't die when using, I turned it off, and then went to finish assembling (I hadn't screwed in the heatsink to the host yet)
 



hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
To get help--you need to do a few things please-

add your general location to your profile page
then go to the WELCOME section and please introduce yourself-

there are threads on why this is a good thing but trust me-its a more polite way--

do that & I will give your rep a +5 bump---

also If I can find your answer by searching --why cant you???

(edit-& BTW that ^^^ is an insult to myself-- lol--not you!)

welcome from Texas
 
Last edited:

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
If you could link me to any threads regarding my issue, I'd love that. I completely understand where you're coming from (I used to be a regular of Newegg's computer building forum, right up until they screwed it all up to be unusable), and I couldn't find any results that would help me with my issue. Maybe my google-foo sucks :)

But thanks for the tips, I'll keep searching for my answer.
 

upaa27

Active member
Joined
Jul 10, 2013
Messages
619
Points
28
That happened on my first build too XD. You want to heatsink the m140 VERY well and not run it for too long or a process known as depolarization will occur due to heat building up. This increases internal resistance until the diode pops. If the diode is still working though all you need to do is heatsink it and it should work fine.
 

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
Well that's the odd bit. I only ran it for about 30 seconds, using the extended tapered copper heatsink from SL. Worked in heatsink but host not together, and when I put it all together, it just wouldn't turn on. Disconnected the diode and put my dummy load back on, tested perfect. The only thing else I can think is I broke a pin off the diode, but nothing came loose, and I bought the diode and module from DTR with leads already attached.

I'll probably cut off the heat shrink and see if a wire falls off tomorrow, but I'm not holding my breath.
 

upaa27

Active member
Joined
Jul 10, 2013
Messages
619
Points
28
30 seconds is around the duty cycle for a c6.

Good luck with the build1
 

Pi R Squared

New member
Joined
May 14, 2013
Messages
3,798
Points
0
2.3A is way too much for a M140, 1.8A maximum. You would be better off turning it down all the way to 1.6A in a C6 or other SL host. I run mine at 1.5A in a C6.

Its also a common mistake to assemble the parts in the wrong order and twist your wires and break something, very common on your first build, some people do it more than once, but I think in this case it was probably the 2.3A.

Alan
 

aryntha

Well-known member
Joined
Nov 17, 2009
Messages
2,028
Points
83
Remember also little things like an insecure driver connection can do this... There's a capacitor on the output of the driver. If the connection to the diode is intermittent, the capacitor will charge, upon disconnection to the diode, and blast the poor diode with a pulse upon reconnection.

That's how I killed a diode on my first build -- not-so-great solder connection. It probably was the current but I"m surprised it wasn't LED'd. Any way to get a micro view and see if your bond wires still exist?
 

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
Unfortunately, I don't have a camera that will go that small. One of the techs I work with has a USB microscope, so I'll see if he will bring that in.

But either way, it's dead. I took apart the module to make sure I hadn't knocked off a pin, and after cutting back the heat shrink, everything was still connected. I removed the diode, put my dummy load back on, and presto: 1.735 mv. On the bright side, I bought a pretty sweet DMM yesterday because it was next to the diodes/resistors at radioshack. An Extech 430 was on clearance/scratch and dent for $20 :).

But the thing doesn't make a peep. The only thing that is left is if it were a broken wire between my solder and the diode, which I don't see being the case. I have to assume the 2.3a killed it, and I got lucky it came on even once.
 

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
2.3A is way too much for a M140, 1.8A maximum. You would be better off turning it down all the way to 1.6A in a C6 or other SL host. I run mine at 1.5A in a C6.

Its also a common mistake to assemble the parts in the wrong order and twist your wires and break something, very common on your first build, some people do it more than once, but I think in this case it was probably the 2.3A.

Oh yeah Pi is correct- too many mA-

Alan
Remember also little things like an insecure driver connection can do this... There's a capacitor on the output of the driver. If the connection to the diode is intermittent, the capacitor will charge, upon disconnection to the diode, and blast the poor diode with a pulse upon reconnection.

That's how I killed a diode on my first build -- not-so-great solder connection. It probably was the current but I"m surprised it wasn't LED'd. Any way to get a micro view and see if your bond wires still exist?
Matt- good advice- failing to short ALL Caps is very common.
even with seasoned builders--

I think by 'insecure connections' Matt means things like
is the use of 'alligator clips'-- too shaky when its a $$$ diode- and quick on /off is bad for diodes- wires just twisted together- too easy for a short-

BTW did you know in Oz they call them 'crocodile clips'

no gators down under but lots of crocs...


+5 to both-

and 5 for the newcomer--
 

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
Thanks to all for the suggestions. I'm sure it was the accidental damage from overpowering it at first. Lesson learned the hard way! Haha, always use a dummy load.

I know my soldered connections were strong, so it wasn't a loose connection.

On a random chance, I looked through the lens with the camera on my phone with the flash on, and it looks like the bond wires are there, but the view wasn't exactly the best, and I know the diode is dead based on my tests, but i was curious.
 

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
how did you test it-?
does your driver work now with a new diode-
or did you try another driver?

Adjustable Power supply??
a good one of those is a must
that and a good LPM


see the pics by DTR- notice the heatsink he is using for the pics.

and in most(or all) of those the diode is pressed into a copper module 12mm first.

DTR can test it for you free- if you want..

hak
 

skels130

New member
Joined
Aug 1, 2014
Messages
11
Points
0
how did you test it-?
does your driver work now with a new diode-
or did you try another driver?

Adjustable Power supply??
a good one of those is a must
that and a good LPM


see the pics by DTR- notice the heatsink he is using for the pics.

and in most(or all) of those the diode is pressed into a copper module 12mm first.

DTR can test it for you free- if you want..

hak
This is my first laser, so I don't have another diode or driver, but I tested by unhooking the diode, and putting the dummy load back on. I got perfect voltage/amperage stability the several times I tested the driver after the diode stopped working. If it was a driver issue past that, from what I have read/understand, the laser would most likely go LED. I bought the diode pressed into a 12mm module from DTR, and put it in a copper heatsink from Survival Lasers.

So i tested it via process of elimination. I tested the driver several times, and left it on for ~30 seconds on the dummy load (until I got a little paranoid about the resistor's temp, and decided I didn't want a campfire) and tested for continuity via my DMM along the wires to the diode, as well as visually checked for loose connections/ pins.

Not that I'm against sending it for testing, but I don't know that it's worth the postage
 

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
you are correct-- DTR was the one who told me that some drivers are made to fail before the diode can be harmed- so 'Reverse Polarity Protection', in some cases does not mean the driver is protected- but is sacrificed to save the (often more expensive) diode.

I have killed a few lasers - by putting the battery in wrong-so I have gotten into the habit of making tiny +s AND -s- (with a fine tip Sharpie)inside the tailcap and/or other places so it will remind me.

Newcomers often , because common flashlights, (with just a few exceptions like Pelican lights) take the battery plus to the front - so without thinking they make this mistake-- so when I ship a laser I insert a slip of paper inside the host as a second reminder- as some will be so anxious to see it lase they save reading any instruction for later- :-0 BIG MISTAKE!

also from DTR- If you by accident put the battery in wrong AND when It fails to laser they IMMEADIATLY turn the laser switch OFF the driaver may escape failing- BUT if they leave it on TOO long or insist on trying more than once something will fail-

I also shut it down quick if you see a new artifact as that could be something on one side of the lens and not a good thing- whatever else you are seeing its not going away by using the switch- so stop at once and look with magnifying glass to see what is wrong-teflon tape got me once that way- melted to the inside lens - so it was toast but at least I did not get any melted teflon on the die window.

-- so a good rule- be ready to hit the switch again every time you replace batteries-

and AFAIK it is never GOOD to turn any laser off and on quickly- the reason this does not harm lab lasers is because the method of 'blanking' is NOT the same as switching on /off/on/off etc

When i must ship laser and battery i place the batttery inside the laser with an insulator( small piece of cardboard) to keep from making any contact with the spring-



MO. is a big state butyou may someday get to St. L and meet up with DTR Jordan in person--

hak
-
 




Top