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yotang 500mWs (need opinion)

mhakali

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Cheap lasers can be a tricky issue. On one hand, you may get a really good deal. However, a very cheap laser may turn out to be too good to be true, and you will end up with a defective unit.
Hello!

Yes. This is exactly why I have started this thread. :) The key note in this is "may".

It would be one thing if several people would have made comments that implies that yotang has great service. And is reliable. Preferably even took a chance buying one of these units. As I see this is not the case I don't know how much clarity I'll gain from it. As I got a recommendation for the slightly more expensive 400mW from O-like I am really considering that one.

I also however know that many of the "pro" laser pointer owners will always and truthfully recommend high end quality companies. They will most likely neglect many dealers such as DX / FP / KD / YT. This may sometimes be warranted and sometimes not. And this is probably and almost always motivated by the regret of making a bad deal. Which may happen in uncharted / uncertain territory.

Doesn't the thought however tickle that these pointers may be a good deal?

If YoTang would be reputable to admit any of their faults and accept and perform refunds I'd probably be willing to take a risk.

I have however not a clue about them.

Mikael
 

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If your intrested I sell the <500mw skylasers which average 485mw after 20 mins on for 600 uk pounds on ioffer, but if qoute your from the laserpointerforoums i will sell them for 450 uk pounds.

have a look
Stop spamming the forum!!!
 

brtaman

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Forget yotang. Go with the laser bryce found for you. It is in your price range, the forum has had great experience with o-like and your power/customer support is guaranteed.
What more could you want? :D Unless you have an LPM you will not notice the difference between 400 and 500mw.



AND "If your intrested I sell the <500mw skylasers which average 485mw after 20 mins"

I call bollocks. Show us a graph or even better post a 20 min long video on youtube.
 

brtaman

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plink

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Hi all,

I'm somewhat disappointed by the advices in this thread because more or less all members so far advised against a try with Yotang. That would be ok if it's based on bad experience but as far as I can see there is simply no experience with Yotang.

Well, I just ordered a 200mW YT27949 , see Wholesale 200mw Strong Green Laser Burning Pointer with Key , so let's see what I get :whistle:

I have no LPM, but I have a high quality NOVA-Lasers 125mW pen and safety goggles, so I can give the dots a close inspection concerning relative brightness, divergence and beam symmetry :yh:

But my reference for beam symmetry and divergence is a Howie Glatter laser, I've seen no other laser pointer so far which was so well collimated, producing the smallest dots on far roofs of all pointers I tested up to now :drool:
 
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Lasher

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If you look up ^ 2 post above you is a link to a thread that expressed just one such "Bad Experience" with Yotang.

I hope you do better with your laser. If you do by all means post a full review but don't doubt these guys here on the forum. They are only trying to look out for the newer members and save them from being let down with there purchase.

Lasher
 

brtaman

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Hi all,

I'm somewhat disappointed by the advices in this thread because more or less all members so far advised against a try with Yotang. That would be ok if it's based on bad experience but as far as I can see there is simply no experience with Yotang.

Well, I just ordered a 200mW YT27949 , see Wholesale 200mw Strong Green Laser Burning Pointer with Key , so let's see what I get :whistle:

I have no LPM, but I have a high quality NOVA-Lasers 125mW pen and safety goggles, so I can give the dots a close inspection concerning relative brightness, divergence and beam symmetry :yh:

But my reference for beam symmetry and divergence is a Howie Glatter laser, I've seen no other laser pointer so far which was so well collimated, producing the smallest dots on far roofs of all pointers I tested up to now :drool:

Hello Plink,

I wish you the best of luck with the laser.

While at first glance it might seem unfair, that we discredited yotang immediately. You have to understands that our quick judgement is based on years of experience dealing with the generic Chinese laser market. The whole "500" mw Focalprice fiasco comes to mind. There have been countless others. This is why the members of this forum are quick to warn newer members that buying a high-power green laser from a manufacturer/outlet which we do not know, is quite a gamble and generally ends with a disappointed customer.

Based on the follow-up thread posted by T_J, it would seem that we weren't in the wrong...

We were all sceptical of o-like in the beginning, but through time and also samples I believe we learnt that o-like is a very decent source of cheap/good quality lasers, which come with a power guarantee.


Best Regards,
brtaman
 

plink

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Hi brtaman and lasher,

just read the bad experience thread with yotang, that sounds bad indeed. On the other hand, at that price there must be a part of gamble in it. :whistle: When I was in Shanghai recently, I bought a 16$ laser from a street dealer (offered for 8$ but he cheated with the change :yabbmad:). The laser came with a diffraction effect filter producing nice changeable patterns but turned out to have a not very reliable switch, but nethertheless I was positively surprised by its perfect round beam symmetry, collimation and output of 60-70mW though it was labeled <50mW (I estimated the power by comparison to my high quality lasers up to 125 mW). I resold it in the meantime but it's an example that it's not always a total loss when you deal with Chinese ;)

So I'm still hoping that I'll get a good one. :whistle:

Btw, had it been a safer decision to choose the DealExtreme: $151.76 200mW Flashlight-Style Green Laser (18650 Battery Included) 200mW Laser ?

Best regards,
plink
 
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The problem with Yotang, and most likely a big contributor to the problems a forum member had, is that they are NOT a laser company. They are a wholesale company.
 

plink

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At last I got the new laser out of customs last week.

The parcel contained the laser, a screw cap with safety key switch, 2 keys and a Li-Ion battery in a protective cardboard box with foam insert and a Li-Ion charger.

After giving the battery a full charge (3-4 hours) I tried the laser.
The only positive experience was that it is focusable.

But the output power showed bad behaviour: after a short flash for a fraction of a second (which could have had the full 200 mW, cannot proove that, was too short) the laser regulated power down to estimated < 50 mW (all estimations based on comparisons with my other green lasers). But even worse, when warming up after more than a minute, it regulated down further until it dimmed completely away. But after further warming up it reappeared to a final output power of < 5 mW.

This behaviour can be reproduced after the laser has cooled down again, i.e. short bright flash for a fraction of a second and so on. The battery is definitely not the cause since it drove the indicator LED to a tremendous constant bright blue light during these tests.

Assumption: bad thermal contact between IR laser LED and heat sink causes LED protective circuit down regulation of output power.

Negotiations with Yotang about sending back the defective laser have begun. I will post that here completely if they continue to give me the runaround like in their first reply.

Since the first flash of the laser (after cooling down) is extremely bright I still hope that the LED is indeed a type capable of generating 200 mW output. Maybe it's really a problem of bad contact to the heat sink. Does anyone have experience with opening such lasers ? It seems to be glued, I had no success to unscrew the laser head by hand so far.

If negotiations fail I will open this thing by any means just for learning, maybe with some luck for repairing...
 

plink

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Hi,

negotiations with Yotang failed, they keep on giving me the runaround.

At least I managed to unscrew the beam focusing head. Then I saw one of the quality problems: a quite excentrically positioned first lens of the beam focusing systems (the second lens is mounted adjustable in the unscrewed head). The first lens is glued to the laser head, so it cannot be adjusted (anyway, I will break the glue and remove the lens).:evil:

The strange thing is that even when the green light vanishes completely away there is still plenty of IR and even dark red radiation coming from the aperture. So at least I will have fun in analyzing this thing (with safety goggles of course) :whistle:

As I promised, here is my negotiation log with Yotang (don't buy there if you want to avoid defective crap ! )

--------------------------------------------------------------------------

Dear Sir

Thanks for your email.

You may misunderstand my mean, I mean all the laser are the same not means
all are defective laser, I mean we can sure all the output power before we
send to our customer, and please believe in us, if

do is our fault, then we will ask the manufacturer to repair or change a new
one to you soon, and we know that you have known whether it is quality
problem or not, right. so please don't worry about it.

Thanks and best regards

YoTang Team

-----Original Message-----
From: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Sent: Wednesday, December 09, 2009 12:51 AM
To: YoTang Team
Subject: Re: RE: RE: Problems with my new laser (Order Number: xxxxx)

Hello team,

after your first reply I expected already been given the runaround once
more. Obviously you are not interested to read my mails carefully, because
you ask things which I clearly ruled out as possible reasons of failure.

There is one important information in your mail:

"we can sure you all the laser is the same"

That means for me that all your lasers are the same CRAP.

So it's spoiled time and money to send you the defective laser back because
I have no hope any more to get a flawless one !!!

It would be ridiculous to accept your silly send back regulations because
you will certainly pretend that the laser is not defective in your "test".
If this "test" is pressing the button for half a second and looking if a
green beam comes out, then the laser will pass such a "test".

So I'm not interested in further arguing with you because it's fruitless !

Of course I will warn all my friends to buy anything from you !!!

A definitely lost customer.

-------- Original-Nachricht --------
> Datum: Tue, 8 Dec 2009 15:23:19 +0800
> Von: "YoTang Team" <support003@yotang.com>
> An: xxxxxxxxxxxxxxxxx
> CC: support@yotang.com
> Betreff: RE: RE: Problems with my new laser (Order Number: xxxxx)

> Hello xxxxxxx
>
> Thanks for your email.
>
> First, Are you sure the battery are full charged? second, you do
> adjusted the focus? one thing we can sure you all the laser is the
> same, we have test it before send to you, the laser has the same
> function
>
> and power with the video show, if you think that the laser has quality
> problem, ok, we can give you return address, but before we give you
> address, please see our regulation first, after we received your
>
> return laser, we will ask the manufacturer to test, if do have
> problem, then we will ask the manufacturer to prepare or change a new
> one to you and send to you for free, but if the laser doesn't have any
>
> quality problems, then you should pay all the shipping cost and send
> the same one back to you. if you agree, then we can give you return
> address soon.
>
> Thanks and best regards
>
> YoTang Team
>
> -----Original Message-----
> From: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Sent: Monday, December 07, 2009 8:58 PM
> To: YoTang Team
> Subject: Re: RE: Problems with my new laser (Order Number: xxxxx)
>
> Hello team,
>
> it's not a matter of focus, that is adjusted right !
>
> The problem is that the laser cannot deliver the advertised power of
> 200 mW but regulates down to a final output of < 5 mW !!!
>
> This could also be caused by a IR pump diode whis has bad thermal
> contact to the heat sink.
>
> YOU SHOULD TAKE THIS SERIOUS ! I WILL DEFINITELY NOT LOVE THIS
> DEFECTIVE LASER !!!
>
> SO PLEASE ANSWER MY QUESTIONS:
> >
> > Do I have a good chance to get a flawless laser if I send my low
> > performing one back to you or do these lasers play all in the same
> > league of questionable very low or defective quality ?
> >
> > In the first case I need to know your regulations about sending a
> > defective article back (your address, is RMA number required, how to
> > avoid double paying of customs tax for the replacement laser, e.g.
> > by adding a repair invoice etc.).
>
> Regards
> xxxxxxxxxxxxxx
>
> -------- Original-Nachricht --------
> > Datum: Sat, 5 Dec 2009 10:56:12 +0800
> > Von: "YoTang Team" <support003@yotang.com>
> > An: xxxxxxxxxxxxxxxxxxx
> > CC: support@yotang.com
> > Betreff: RE: Problems with my new laser (Order Number: xxxxx)
>
> > Hello xxxxxxx
> >
> > Thanks for your email.
> >
> > Are you sure that the laser is 5mw? after i see your email, i can
> > sure you are not a maser about laser, you know this laser can adjust
> > the focus, it can offer different beam light and power, so i sure
> > you
> >
> > haven't adjusted the focus, we also can sure you that we have tested
> > before send to you and seldom of laser have problems. so just try
> > again, i sure you will love it.
> >
> > Thanks and best regards
> >
> > YoTang Team
> >
> > -----Original Message-----
> > From: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > Sent: Saturday, December 05, 2009 6:47 AM
> > To: YoTang Team
> > Subject: Problems with my new laser (Order Number: xxxxx)
> >
> > Hello Team,
> >
> > I've finally got my new laser out of the customs today and tried it.
> >
> > But I was very disappointed by the output power and its strange
> > behaviour during long operation.
> >
> > At first, I charged the battery for 4 hours (charger LED changed
> > from red to green already after 3 hours).
> >
> > When I then operated the laser, it gave at first a very bright spot
> > for a fraction of a second (maybe the full 200 mW) but then it
> > dimmed at once to an estimated output power of <50 mW.
> > Even worse, on long operation > 1 min., when the laser gets warm,
> > the spot becomes fainter and fainter and then vanishes completely!
> > After some more minutes of operation, when the laser gets to its
> > maximum temperature, the spot reappears and reaches an estimated
> > output power of
> <5 mW!
> >
> > My estimations are based on comparisons with my other green lasers
> > with powers between 5 mW and 125 mW.
> >
> > It's important to know that during the whole operation time the blue
> > indicator LED gave an extremely bright light not dimming at all, so
> > the problem can not be caused by the battery.
> >
> > I think the problem could be located in the regulator circuit of the
> > laser diode or in a badly selected set of crystals for the frequency
> > doubling of the IR primary radiation.
> >
> > My question is:
> >
> > Do I have a good chance to get a flawless laser if I send my low
> > performing one back to you or do these lasers play all in the same
> > league of questionable very low quality ?
> >
> > In the latter case, I would try to open this thing and at least, I
> > would learn something about its configuration, at best, I would
> > repair/tune it up to the full 200 mW...
> >
> > In the first case I need to know your regulations about sending a
> > defective article back (your address, is RMA number required, how to
> > avoid double paying of customs tax for the replacement laser, e.g.
> > by adding a repair invoice etc.).
> >
> > Best regards
> >
> > xxxxxxxxxxxxxxxxxx
> >
> > --
>
> --
> -
 

mhakali

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*gives plink a cookie*

They are hopeless. They will run you dry of frustration.

If you are lucky they may accept your return.

But they will not refund shipping either way. No matter what you hear them promise.
 




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