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new green laser dims suddenly (video)

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dawsonmobley

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I'm currently trying to get the laser exchanged but the site I bought it from is saying the way it's working is normal....I don't think it is but figured I would ask before I reply to them.

It is a cheap (100mw) green laser so I knew it was a crapshoot when I bought it but I would like it to at least work at full power for more than 10 seconds.

You can easily see the problem in the video but I will just say the temperature was 76f so it wasn't too cold and I have brand new energizer batteries in it...also it has worked this way from the first use a couple weeks ago. I only leave it on for a few seconds in the vid but if I keep it on after the brightness drops it will gradually dim to the point you can hardly see it over a few minutes.


so is this behavior normal for cheap green lasers or should I try to get a refund or replacement from the seller?
 





Unfortunately this seems pretty normal. Cheap 532nm pens are a crap shoot.
 
Bad MCA. If you "blow up" the beam using a single convex lens (a magnifying glass or jeweler's loupe will work) so the beam is the size of a baseball you may see it change shape.

Get it replaced, it should never do that.
 
weeba2kv said:
New batteries or warm it up in your ass :) to reach 37.C
Click to expand...

the video was with brand new batteries so I'm pretty sure that's not the problem.

If it were being caused by it not being warm enough wouldn't it start off with a weak beam? The strongest beam is for the first ten seconds or so and after that it suddenly drops off by about 50% and then gets progressively dimmer if I keep it on.
 
Last edited:
It could be mod hopping
Doing the "expanded" spot (mentioned by Nordhavn) with the magnifying glass will tell you if the spot changes shape or not

It could be a bad connection somewhere

It could be a bad component on the driver

Whatever it is, if it is "new" AND you are using good batteries, then it is defective and needs to be replaced

Peace,
dave
 
I have one with the same host @54mw. I doesn't start to dim until it gets hot. After cool down its bright again. I have been using the same Energizer Lithium batteries for several months...
 
I will say that I've had quite a few cheapos where the problem ended up being the poor battery connection to the end cap due to worn or not enough conductive material there. Easy way to tell is if you have another pen unit just screw the bottom half on and see if it works better. If you have a small magnet you could try putting it on the battery before dropping it down into the tube.
Agree with what others are suggesting you try for an answer. Own about 25 $5 dollar 532nm pens and they are very suceptible to all these things. Hey, for $5 bucks they have ranged anywhere from 15mw to just over 100mw:) Of course I've also had some read almost 50% IR:(
Want a nice likely more stable output with low IR you'll likely have to pay quite a bit more although the $10 Fasttech modules are a great deal with about 10% IR from what I've seen (don't come with a host though).

Maybe I missed it but where did you purchase it and how much did you pay?
 
confirm. looks like the typical issue of the cheap greens. nothing you can do. only ask seller to replace with a new one.

if the laser starts with mode hopping you may also see this when "moving" the dot quite quick.
 
Pman said:
I will say that I've had quite a few cheapos where the problem ended up being the poor battery connection to the end cap due to worn or not enough conductive material there. Easy way to tell is if you have another pen unit just screw the bottom half on and see if it works better. If you have a small magnet you could try putting it on the battery before dropping it down into the tube.
Agree with what others are suggesting you try for an answer. Own about 25 $5 dollar 532nm pens and they are very suceptible to all these things. Hey, for $5 bucks they have ranged anywhere from 15mw to just over 100mw:) Of course I've also had some read almost 50% IR:(
Want a nice likely more stable output with low IR you'll likely have to pay quite a bit more although the $10 Fasttech modules are a great deal with about 10% IR from what I've seen (don't come with a host though).

Maybe I missed it but where did you purchase it and how much did you pay?
Click to expand...

I'll try the battery idea but the behavior is exactly the same everytime I use it so I wouldn't expect that if it was a intermittent or weak battery connection.

I got it from BangGood.com for about 20 bucks, it was advertised as a 100mw laser. And for the first 15 seconds I use it at night it is very bright and a very strong easy to see beam but once it dims the beam is hard for anyone to pick out unless they're holding it so it's not much use for star pointing.
 
This probably doesn't work but HERE's a video showing how to fix it. They actually link back to THIS thread in the description of that video.
 
Gun said:
This probably doesn't work but HERE's a video showing how to fix it. They actually link back to THIS thread in the description of that video.
Click to expand...

Unfortunately, it's not that simple
It would be nice if it worked for him
However, that only covers one possible cause of the dimming

Peace,
dave
 
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Gun said:
This probably doesn't work but HERE's a video showing how to fix it. They actually link back to THIS thread in the description of that video.
Click to expand...

no go on mine....wrapping my hand around the end did make it brighten up maybe 10% for about 15 seconds (this was after it had the brightness drop of over 50%) but then it went so dim it was hardly visible outside at dusk.


I see a lot of these larger green laser pointers (in seemingly nice aluminum bodies) on ebay but they all say they are 5mw and run around 20 bucks or so. I know the mw power ratings are hardly ever accurate but do they advertise it as 5mw so they can sell them here and they are actually more powerfull (wishfull thinking?)? Is a focusing ring worth looking for on them or more of a gimmick?
 
Measure the battery current draw to rule out the electrical system as the cause of the problem. It should be constant.
 
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