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803T's dieing in MXDL host, HELP!!

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nvmextc

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I'm trying to make my first 803 in a MXDL 5W host, the one with jayrob's heatsink. I'm using rckstrs drive at 150ma and 3 Ultrafire 10440. So far I'm on my 2nd diode and can't understand what's happening. I'm hoping someone can shed some light on this.

The first one I had in worked strong for a few minutes, then after a few clicks of the button it was dim, very dim, I tested the diode and believe it's dead now.
So I put in the next 803 diode, it seems to be working alright, I measure 70mW with my laserbee LPM  :-/, again after a few moments this diode dims out, I don't test it or anything, was 2am so I went to bed. But when I woke up this morning it is working fineish again but running @ 36mW! :-? This one still dims out, but if I apply pressure to the torch in the right spots it seems to stay alright... In writing this post, now I think this diode is dead, won't even make a dim light now.
Btw i tried to keep a duty cycle of 30/30 when I was testing these, so it's not that I've left one on for 10 minutes. Anyone know what's happening to my diode's? I'm completely stumped. Thx for anyhelp.
 





daguin

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nvmextc said:
I'm trying to make my first 803 in a MXDL 5W host, the one with jayrob's heatsink. I'm using rckstrs drive at 150ma and 3 Ultrafire 10440. So far I'm on my 2nd diode and can't understand what's happening. I'm hoping someone can shed some light on this.

The first one I had in worked strong for a few minutes, then after a few clicks of the button it was dim, very dim, I tested the diode and believe it's dead now.
So I put in the next 803 diode, it seems to be working alright, I measure 70mW with my laserbee LPM :-/, again after a few moments this diode dims out, I don't test it or anything, was 2am so I went to bed. But when I woke up this morning it is working fineish again but running @ 36mW! :-? This one still dims out, but if I apply pressure to the torch in the right spots it seems to stay alright... In writing this post, now I think this diode is dead, won't even make a dim light now.
Btw i tried to keep a duty cycle of 30/30 when I was testing these, so it's not that I've left one on for 10 minutes. Anyone know what's happening to my diode's? I'm completely stumped. Thx for anyhelp.
Click to expand...


If the output changes with changing "pressure" on the host, you probably have a poor connection somewhere or something is shorting out. You needs to figure out what is "moving" when you apply the pressure. Is the driver moving? This might be the worst because it could cause an intermittent "break" in the power to the diode and cause the diode to be "fried" when it reconnects. Is the "head" moving? You may be loosing the ground. Is the tail screw or "clicky switch" moving? Did you test the driver with a dummy load to make sure it is working right?

Peace,
dave
 
MarioMaster

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well seeing as how you've said you can get it to brighten and dim you have a bad connection somewhere, constant current drivers and loose connections are a bad combination and can blow your diode
 
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nvmextc

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Well I think it may have been the aluminium piece inside the top of the body where the + of the batteries hit that was moving from the body. And no I haven't tried a dummy load at all, I've never done that with anything, what would be a good dummy load?
 
pseudolobster

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4 diodes in series, a couple LED's, or ideally, one of your dead 803t's.

(so what you probably want to do is disconnect one pin of the "dead" laser and place your multimeter in there, bridging the connection)
 
jayrob

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nvmextc said:
Well I think it may have been the aluminium piece inside the top of the body where the + of the batteries hit that was moving from the body. And no I haven't tried a dummy load at all, I've never done that with anything, what would be a good dummy load?
Click to expand...

Also check the battery pack. The plastic holder has some plastic 'tabs' that hold the small metal contact point in place. These tabs are kind of 'thick'. The 10440 batteries have a 'shallow' positive end point. Most likely, the batteries are not getting a good connection at the positive end. Check the voltage reading from the battery pack alone...
Jay
 
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nvmextc

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OK, I've taken out that first diode, the pins seem to have come off at some stage (I'm thinking whatvere was making it dim out was heating up the driver and disconnected the pins maybe?) I put the diode in a test circuit and I'm getting 50mW with an acrylic lens @ 125ma. lases great, just a lil underspec i believe.

Jayrob, I'm getting 0V on the battery pack, while on each battery I see ~4.1V, Maybe 1 battery is out and applying pressure to the barrel fixes it? Though this torch is very solid and I still can't understand why applying pressure makes such a change when I can't see it moving.

And what do I do with this dummy load, bridging the connection with the DMM, does that check current and that the diode is getting power? Sry, I'm a bit of a noob with the DMM, and hardly pull it out.
 
jayrob

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nvmextc said:
OK, I've taken out that first diode, the pins seem to have come off at some stage (I'm thinking whatvere was making it dim out was heating up the driver and disconnected the pins maybe?) I put the diode in a test circuit and I'm getting 50mW with an acrylic lens @ 125ma. lases great, just a lil underspec i believe.

Jayrob, I'm getting 0V on the battery pack, while on each battery I see ~4.1V, Maybe 1 battery is out and applying pressure to the barrel fixes it? Though this torch is very solid and I still can't understand why applying pressure makes such a change when I can't see it moving.

And what do I do with this dummy load, bridging the connection with the DMM, does that check current and that the diode is getting power? Sry, I'm a bit of a noob with the DMM, and hardly pull it out.
Click to expand...

If you are not getting 12 volts when you test the battery pack, then there are contact problems with the positive end of the batteries. Go back to my last post, and read it again... It explains what the problem is...
Jay
 
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nvmextc

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Yer thx Jay I think this is just it, squeezing the pack I can get 2-4v, I'll try get some spacers in there and see if I can get the full 12v. And I think the low power readings on teh test circuit was just not enough voltage being supllied (old batteries I just remembered, I just replaced some batteries and got 90mW :))
 
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