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Replacing the LD on my RPL...

freshert

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Glad to see you got it fixed. :)My DX150 has the same problem your RPL blue had. The diode doesn't light up, now I think maybe its because of metal shavings on the circuit board. Can you give me any advice on trying to clean the circuit board of a laser?
 

GooeyGus

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styropyro said:
I'm glad you got it fixed, but for some reason I remember reading that a crystal in the 473nm process is pretty hygroscopic, can anybody confirm this?
I think it depends on which crystal is used. Now, really I'm just making a guess here because I remember reading that somewhere as well. But, I THINK there are two different types of crystals that are usually used in the 473's. One is LBO and the other is BiBO. I think one is fine in open air, and the other is usually packaged in N2.

Remember, this is just an educated (barely...) guess.
 

Beren

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Hey Ace, is the light from that diode hitting the crystal set collimated or uncollimated? I should probably be able to tell from the pictures, but I'm too much of a n00b.
 

Ace82

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freshert said:
Glad to see you got it fixed. :)My DX150 has the same problem your RPL blue had. The diode doesn't light up, now I think maybe its because of metal shavings on the circuit board. Can you give me any advice on trying to clean the circuit board of a laser?
Sorry for the late reply, just been extremely busy lately.  I actually have a functional DX150 driver and diode, but no crystal or optics what so ever.  Maybe one of us should sell our parts to the other! Anyway, I don’t think the metal shavings have anything to do with it.  I dropped the RPL, and a ground contact screw came loose in the driver.  The metal shavings has been there from the beginning and there was never a problem before.  On your 150, first check the contacts.  How much have you used it, and how long do you duty cycle it?  Because the diode could have blown.  

Beren said:
Hey Ace, is the light from that diode hitting the crystal set collimated or uncollimated?  I should probably be able to tell from the pictures, but I'm too much of a n00b.
The IR 808nm coherent light coming from the diode is never collimated before it hits the crystals, and that goes for green as well.  There is a “GRIN” lens on the diode aperture that helps narrow the light to the crystal set (per Jack).  But the diode direct is insanely powerful, and insanely dangerous.  For fun, I decided to aim the laser away from me when I new the diode was operating, and powered it up about 4” away from some electrical tape, and made sure that no reflections would hit my eye, but also did it for not more then 1 sec because I know how dangerous it is, and the tape practically caught fire!  It melted and smoked so quick, even though the light was not collimated.  

Diachi said:
Did jack get back to you about the under spec green ?

Diachi
Actually, he sent me a nice long detailed email explaining how I should not even try to take it apart, and that it would be best to send it for repairs.  But since the Olympics, China has completely stopped fabrication and repairs of all lasers, (per Jack) so I would have to wait about 3-4 months at least!  He did not say anything about underspec unit, although I made it very clear I was interested.  I think he just sends them back because he tests every single one and if they don’t perform up to par, he rejects them.  As far as the broken ones, he sends them in for repair or warrantee, so my assumptions are that he didn’t say because he doesn’t have any.  


In conclusion, I actually love this laser more, after better understanding the inner workings, and with my personal touch, the unit operates better!  I focused it to have better divergence then before, and the mode hop issue has significantly improved.  My 225 also needed adjustment for more power.  I didn’t acquire more power (no I don’t have a meter, but 30mW is pretty noticeable when you know exactly what to expect) but the mode hop now takes about 8-12 min on instead of 4-8 like before.  But all in all, these units are excellent, extremely durable, and well designed.  
 

darklandz

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great work on repairing the laser. :) has the divergence really got better after the repair? i dont understand why the manufacturers just dont have the lens preset for best divergence.
either way, this has to be one of the best RPL Blue threads.
 

Ace82

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darklandz said:
great work on repairing the laser.  :) has the divergence really got better after the repair? i dont understand why the manufacturers just dont have the lens preset for best divergence.
either way, this has to be one of the best RPL Blue threads.
Thanks! The repair really has nothing to do with the divergence improving. It's just the front "heat sink" cap that has the final collimator lens on that I left unscrewed about 1/32" and got it focused significantly better. It is supposed to be set for the best, but I don't know why sometimes a little personal tweak with a little love from the owner can improve it.
 

freshert

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Ace82 said:
 [quote author=freshert link=1216408119/20#33 date=1216541493]Glad to see you got it fixed. :)My DX150 has the same problem your RPL blue had. The diode doesn't light up, now I think maybe its because of metal shavings on the circuit board. Can you give me any advice on trying to clean the circuit board of a laser?
Sorry for the late reply, just been extremely busy lately.  I actually have a functional DX150 driver and diode, but no crystal or optics what so ever.  Maybe one of us should sell our parts to the other! Anyway, I don’t think the metal shavings have anything to do with it.  I dropped the RPL, and a ground contact screw came loose in the driver.  The metal shavings has been there from the beginning and there was never a problem before.  On your 150, first check the contacts.  How much have you used it, and how long do you duty cycle it?  Because the diode could have blown.[/quote]
Sorry but I already shipped the laser back to DX for a refund. I tested it with my multimeter and the laser was only sucking up an average of 50ma :-? I only left it on for about 10minutes max and the laser was only warm. The diode was not blown, after some tinkering I could see a tiny bit of IR coming out with my phone camera.
 

Ace82

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freshert said:
Sorry but I already shipped the laser back to DX for a refund. I tested it with my multimeter and the laser was only sucking up an average of 50ma :-? I only left it on for about 10minutes max and the laser was only warm. The diode was not blown, after some tinkering I could see a tiny bit of IR coming out with my phone camera.

Sometimes a “blown” diode will still partially work at like 5% or something, and can detect a faint amount of IR and sometimes more or less heat then before.  What was your average duty cycle?  If you leave it on for several minutes past the recommended 1min on/1 min. off, then the diode undergoes extra stress since there’s no real heat sink on these units.  My 150 used to get really warm on the outside after 30sec.  on fresh batteries.  Anyway, you already sent it to dx, so now you just need to wait it out!  Let me know how that works out!
 
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ok i have a noob question ... isn't the point of a heat sink to dissipate the heat usually through the air ? how are you going to put heat in the air if the outside of the laser doesn't get hot and you have no air flow through the laser?
 
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Maven said:
ok i have a noob question ... isn't the point of a heat sink to dissipate the heat usually through the air ? how are you going to put heat in the air if the outside of the laser doesn't get hot and you have no air flow through the laser?
Actually it is to dissipate heat through the material you are using, you don't want air pockets in the laser because heat will trap in them and cause your diode to blow...
 
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maybed you didn't see what i was saying ... if it is getting warm on the outside that means that it is dissapating heat ... if it doesn't get warm on the outside then the heat is ofcourse stuck in the laser ... if you have a good enough heatsink then the heat will never build up enough to get things warm but if you don't get the heat to the air outside of the laser then it will build up inside the laser
 

Ace82

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Maven said:
maybed you didn't see what i was saying ... if it is getting warm on the outside that means that it is dissapating heat ... if it doesn't get warm on the outside then the heat is ofcourse stuck in the laser ... if you have a good enough heatsink then the heat will never build up enough to get things warm but if you don't get the heat to the air outside of the laser then it will build up inside the laser
You are correct.  As with any air cooled device, there needs to be physical dissipation.  That is why, aluminum is usually in a shape that collects air channels.  That is the reason why the RPL has a ribbed cover.  That is why aluminum heat sinks have channels which are surfaces to be hit with friction from air, it actually cools it.  



That is why, the RPL's have such a greater duty cycle then the average pen.  The average pen doesn't contain a aluminum heat sink large enough to collect air flow, (plus their usually sealed...well mostly).  So yep, that's the just of it.  




Why else would there be a fan?
 

Petrovski

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Yep. The reason why many heatsinks have 'ribs' is to increase their surface area. Larger surface area = more transferral of heat. And of course, with forced air cooling the transferral capacity will increase even more.
 

freshert

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Ace82 said:
[quote author=freshert link=1216408119/20#39 date=1216903431]
Sorry but I already shipped the laser back to DX for a refund. I tested it with my multimeter and the laser was only sucking up an average of 50ma :-? I only left it on for about 10minutes max and the laser was only warm. The diode was not blown, after some tinkering I could see a tiny bit of IR coming out with my phone camera.

Sometimes a “blown” diode will still partially work at like 5% or something, and can detect a faint amount of IR and sometimes more or less heat then before.  What was your average duty cycle?  If you leave it on for several minutes past the recommended 1min on/1 min. off, then the diode undergoes extra stress since there’s no real heat sink on these units.  My 150 used to get really warm on the outside after 30sec.  on fresh batteries.  Anyway, you already sent it to dx, so now you just need to wait it out!  Let me know how that works out![/quote]
My average duty cycle was probably 5 minutes on 2 minutes off when I was burning stuff. When I just looked at the beam it would probably be 30 seconds on 10 seconds off.

EDIT: I think its a driver problem because before the laser died completely it would work for about 2 minutes then shut off and not work for a while.
 




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