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Ebay Laser Watchdog Group

Alaskan

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Those who would like to help stop ebay member fraud relating to lasers please assist.

I do not recommend anyone identify their ebay member ID's in the forum, or even to privately share them with anyone as it is not necessary to accomplish the task. It isn't even necessary to respond to this thread or let yourself be known to help with this. Members can simply help by contacting ebay sellers who for whatever reason have bad info on their listings and letting them know about the error, or misrepresentation. To help promote a watchdog group, however small (perhaps a lone wolf) I'm going to be adding links to listings I see as fraud, or ebay sellers who are well known to over rate the power output of their listings or any other purposeful misrepresentation.

Please post links to ebay sales of laser related items here which you believe or know are fraudulent. What we can do is encourage members to individually contact the seller and point out the problem. Hopefully, this will cause some listings to be changed to reflect reality. If the items are low enough priced, I am willing to buy a few myself to allow appropriate feedback to be left for those sellers.

Why? Ebay won't allow feedback to be left for sellers who refund the purchase, due to this many ebay sellers are working the system to cheat buyers and hiding the fact by simply refunding when there is a complaint to prevent members from leaving feedback of what is really going on. Many buyers accept the loss, especially when the cost to send the item back exceeds its value, as many items sold by China sellers are.

As long as there is a feedback system on ebay, we can circumvent their underhanded method of hiding what is really happening, but at a cost, of course. I'm willing to do a few small purchases a year to help keep the laser listings on ebay honest, especially due to the mass amount of misrepresentations coming from China laser listings.

I just bought a misrepresented item from a US seller who was listing a M140 laser diode at 465 nm. I confirmed he knew it was 450 nm from this response:

ebay seller critical_eye_studios

The above ebay seller just responded to my message asking him if he listed them as 465 nm in error, why he hasn't fixed his listing yet with the following;



He thinks I am complaining because I'm a seller in competition with him, wrong, I sell nothing. Can one or more members please message him telling him how wrong he is about the wavelength being unimportant? What doesn't make sense is if it is unimportant, then why is he listing them at a more sought after wavelength? I have a very critical eye to misrepresentations regarding lasers or laser parts, we get enough of that from the China sellers.

2 (Two) High Power M140 Laser Diodes 4.2W 2.1W ea. Blue 465nm | eBay
This purchase resulted in a neutral feedback as a warning, but he deserved a negative. I was willing to purchase them item because I can both use the diodes at 450 nm as well as push forward a warning to other buyers if he lists more of them at 465 nm. Due to this, buying them wasn't a loss and a sweet situation. Might seem underhanded of me, but this guy was misrepresenting these diodes on purpose to drive more buyers to his listing, but not clarifying the misdirection further in the listing which is clear fraud.

After leaving a neutral with a simple statement that the diodes were not 465 nm and were 450 nm, the seller responded with insults due to where I live and threatened to attack my legitimate honest listings by buying one of them and giving a negative feedback. My mistake! I should have understood if this seller was willing to misrepresent his listings, he would also likely be willing to lie about anything. Due to this, I need to do this work with a different account where I don't sell anything to keep dishonest folk like this from being able to push back. For this guy, if he does that I have another plan for him.

FYI: Sellers cannot give buyers negative or neutral feedback anymore. If you are selling something they can try to neg you in retribution, but unlikely unless a small inexpensive item. If someone is suspect of buying something to allow a retribution feedback, refund the money and they cannot leave feedback, using ebay's trick to hide dishonest sellers back at them when they try to do that. You can also add them to your blocked buyers list and ebay will then automatically cross reference any other account they might have to block that one too. IMO Ebay does a lot of unethical business practices, but at least they have that one right.
 
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Alaskan

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I just wrote that seller asking what the design CW power output rating is, waiting for an answer but from my own experience won't be 400 mw, I bought some too and they won't do that for me. They might not have sold you the 840, maybe a lower power diode such as the LPC-826 or 836? Part of the problem is some sellers are listing the power output they believe, or were told some can produce. Not what they are specified to reliably produce, but I've never been able to find a spec sheet for that diode anywhere, only a data sheet for a variant of that diode and it is rated for 150 mw output.

existotem appears to be a run of the mill China seller, but even some sellers over there who are considered honest by most are listing that diode at up to 380 mw output which I am sure isn't the design power out. I couldn't get mine to produce 380 mw of raw output before collimating. Maybe someone here has, if they got a true "LPC-840"?

Here's a direct download link to the data sheet I found for a reported variant of the LPC-840: https://photos.imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/laserdiodedatasheets/lowdivergencelaserdiodedatasheets/ML101U29 LPC840 7-14 min 10.5-16 typical 12-20 max.pdf

Can you check your diode and report back which one of these three you think it looks like?



 
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lasersbee

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Looks like that same guy has the same eBay
listing back up....

2 (Two) High Power M140 Laser Diodes 4.2W 2.1W ea. Blue 465nm | eBay

I just sent him a freindly Heads Up eBay message
about his Wavelength "error" in his listing...
Hi,
just thought I would give you a heads up.
The Laser Diodes from the Casio projector are
not 465nm Diodes. They are 450nm Laser Diodes.
Perhaps fixing that on your listing would reduce
any returns from eBay Members that have a
Spectrometer.

regards,
lasersbee
Let's see his response....

Jerry
 

Alaskan

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Thanks Jerry, I thought he might have more.

Re: the existotem LPC-840, when I asked, he gave a CW power rating of 250 mw, not what his listing indicates. His answer;



Existoterm is another ebay listing liar, here is what his listing says about the CW rating:



looks like i found another item to buy so i can report what he is doing.
 
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deadshadow

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i bought 2 diodes from them,1 is already in a build and the other one is this



looks like lpc836?i dont know but thats whats looks like to me from your comparison photos.

i already knew at the time i bought them that those are out of specs but i wanted to try them myself.on the one i build i got 300mw with 390ma curent with G2 lens.i'll try to dig some old lpc-836 test to compare it with 836s graphs
 

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Alaskan

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I don't see that stamp in the same place and no paint, anyone?



Maybe show the emitter as clear as you can too?

Here's a photo of his LPC-840 diodes from ebay, it does look like one of those and he did admit in message the CW rating is different than his listing shows; lower.:



http://www.ebay.com/itm/Mitsubishi-LPC-840-650nm-400mW-500mW-Red-Laser-Diode-TO18-5-6mm-1-pcs-/231446679040

Still, it isn't uncommon to find mention all over the internet they can do 350 mw, but mine fried at that power when heat sinked well. Bad luck or they are being pushed far too hard by hobbyists? Looking at this last photo the marking placement is very inconsistent. The one on the bottom left also has a significantly larger icon mark, did he mix 836 and 840's in the same photo? Is he selling them that way too? Mixed up? Looks kinda sneaky stuff to me. The stamp on your diode isn't the larger size one, I don't know, can they be that inconsistent or is that an indicator of a different part?

My guess is you got LPC-836 diodes, not what you paid for. Maybe I was ripped off with the lower value laser diode when I ordered one too. Now that I see the clear difference in the size of those markings, I think I did.
 
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deadshadow

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oh it looks like they definetly messed up those diodes and mixed them.if a photo of the emitter helps,i'll try to get one.they are lower output for sure and we seriously overdriving them thats why they tend to fail randomly
 

paul1598419

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I have been using LPC-840s for a long time now. They aren't dying at 350 mW as I have one now close to 400 mW. It probably depends on the lens you are using how much power in CW you are able to get. I use a single element aspheric lens for mine. If you use an acrylic on multi-element lens you will get less power out.
 

deadshadow

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I have been using LPC-840s for a long time now. They aren't dying at 350 mW as I have one now close to 400 mW. It probably depends on the lens you are using how much power in CW you are able to get. I use a single element aspheric lens for mine. If you use an acrylic on multi-element lens you will get less power out.
does anyone sell this kind of lenses on the ebay paul?i dont have any of those and i would really like to get on if the price is right.

also what current you running your diode to get 350 and 400mw?
 
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paul1598419

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There are many sellers of these lenses. AxiZ sells one for around $8.00. Techhood sells some, but the price changes from $8.00 to $10.00. There are many other as well. You have to search. DTR sells, or used to sell, a cheap version for $10.00.
 
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Alaskan

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Thanks Paul, I bet we are pushing the LPC-840 way above its designed CW rating, as many, but if you got the 836 instead, even harder. Perhaps ebay seller existoterm is giving the correct design rating for CW @250 mw, but his listing showing the top end of output when driven hard, except it appears you received a lower rated diode?
 

paul1598419

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I don't think so, Chris. I checked all this out sometime ago and the spec sheet for the 840 is ~50 mW higher than the 836. I had a problem with the first few, but chalked that up to a very cheap driver. I use an adjustable X-Drive with these now and have not had problems with them since. I still have a couple in my stock, so I could push one until it dies, if that would help. I'm not even sure the 836s are still available on eBay any longer as that was what I was told about a year ago.
 
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Alaskan

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LPC-836 diodes are still on ebay, found some when looking earlier. I do remember the 840 could output 50 mw higher, I believe someone sold me some 836's, why the two I had died may have been due to running them too hard thinking they were 840's, reflections or driver issues, perhaps something I did back then when new to this hobby.
 

RedCowboy

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It really makes you appreciate DTR after dealing with ebay cheats selling fakes, I don't believe that they are the least bit confused about the difference between 445 and 465, they just flat out lie is what I think..
 
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