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help w/ broken PHR pointer

Zinsii

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Hello, I just finished my first ever laser build, its a PHR using the flexdrive at 125mA. It worked great for about an hour, but now when I turn it on it flashes the bright purple it used to be, then goes extremely dim and stays dim. Whats wrong? do I need a new battery? (I didnt use it that much at all)
 



cust11

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It sounds to me like the flexdrive is dropping below its voltage threshold of 2.5v. Check your battery voltage. You may be too low or too high. (*2.5-5.0)

-Mike
 

Zinsii

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I dont have anything to measure voltage, its using the 3v 123 battery... do you think I could have used it up that quickly? how many minutes of continuous operation should that battery last for?
 

cust11

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I dont have anything to measure voltage, its using the 3v 123 battery... do you think I could have used it up that quickly? how many minutes of continuous operation should that battery last for?


How did you set and verify your driver if you do not have a DMM? I don't know how much run time you will have but if it is a NiMH battery it wont be very long. Remember once the driver gets 2.5v it turns off. You may have 2.8v~ at the battery but you will get a little vloss from your switch etc.

-Mike
 

potatorage

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How did you set and verify your driver if you do not have a DMM? I don't know how much run time you will have but if it is a NiMH battery it wont be very long. Remember once the driver gets 2.5v it turns off. You may have 2.8v~ at the battery but you will get a little vloss from your switch etc.

-Mike

It doesn't turn off completely, for mine, it flashed and was very dim. I think your primary CR123 is dead, and you need a new battery
 

Zinsii

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I ordered the driver preset, but I wasn't able to confirm it. I actually had another battery lying around, and I put it in and the same thing happened... do you think my flexdrive got fried somehow? what could have happened? I just turned it on one time and it started doing this...
 

cust11

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My money is on bad batteries. You have no way to verify their voltage so I am sticking with that until we gather more information.

-Mike
 

Zinsii

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no, I know for 100% sure that the other battery I tried was fresh. its not the battery, it has to be something else >.>

potatorage, did you have a similar problem?
 
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Meatball

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I'm surprised your diode is surviving all of this mess.. PHRs are tough though.

If you can, the best way to determine the problem would be to disassemble your build, disconnect your diode, reconnect a test load, and measure the current you get from your batteries, and then the current you get from any other 2.5-6V source. This will narrow down the problem to either bad batteries, or a bad driver.
 

Zinsii

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it seems like it must be a bad driver, because I know the battery is good. is there anything that can cause the driver to just die like that? if I had a defective one could I get another for free from them?
if the diode was broken, I wouldnt be able to get this weak beam right?
 

cust11

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it seems like it must be a bad driver, because I know the battery is good. is there anything that can cause the driver to just die like that? if I had a defective one could I get another for free from them?
if the diode was broken, I wouldnt be able to get this weak beam right?


All of those problems are plausable. Without a DMM though, it will be hard to pin point the problem. Drlava offers a repair service. IIRC it is flat rate $12. Although I am pretty sure it has to be a driver purchased from him.

-Mike
 

Meatball

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if the diode were dead.. (especially a PHR) it would be SUPER dim. I know what an LEDed PHR looks like.. if your diode was dead, you wouldn't get the initial bright flash that you've described..
 

Zinsii

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I bought it from him, yes, I'll have to get in touch with him. I was hoping to have the laser by this saturday, so hopefully I can figure something out. thanks for your help
(I'm a bit of a noob, how exactly would I use a DMM to find the problem, and what do they cost?)

@meatball... its REALLY dim. I can barely see it in low light even like 2-3 feet away on a white surface. but when I first start it up, it flashes as bright as it was before... very bright - could a dead diode put out that for a moment?
 
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cust11

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I bought it from him, yes, I'll have to get in touch with him. I was hoping to have the laser by this saturday, so hopefully I can figure something out. thanks for your help
(I'm a bit of a noob, how exactly would I use a DMM to find the problem, and what do they cost?)


A fairly cheap one should be available at Radio Shack etc. As for checking the driver, I would start by verifying continuity of the anode and cathode (+ & -) across the driver. I would also build a test load to verify the current setting. (it could have been bumped). Jerry(laserbee) is giving away free 1ohm 1/2w resistors so you may want to grab one of those for your test load. They are quite difficult to find.

I really, really think that your batteries could be low. The conditions you described match more with low battery than a dead diode or damaged driver.

-Mike
 

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Zinsii

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I just tried the new battery again, I really wish that was the problem but its not. I might pick up a DMM tomorrow, and I'll toss drlava a PM. have you ever had a laser with good batteries behave like this?
 

cust11

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My PHR had a pulsing problem because I was running 4.2v and the driver wasn't happy! Don't be discouraged with this small problem. I am sure it will be a simple fix. We will try our best to help you figure out your problem in the most cost effective manner possible.

Like I mentioned before, that battery may not be good either. Even after you measure the battery it may read 2.8v~ but after the slight voltage drop across the switch and wiring, the driver will suck that battery down really fast and cut the diode off. I would suggest using Lith-ion rechargeables in the future.

-Mike
 




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