Best Practice in purchasing NUBM31t or MLD's

[additude]

Hello.
What would be the best practice, rule of thumb, in purchasing a NUBM31t LD? or is it just a crap shoot? How can a person decide if a purchase is a fair deal or not? Are OSRAMS less desirable than Nichia?

 

[RedCowboy]

The Osram array's gang lens is focused short and they have a lot of overspray/glare, I won't buy anymore of them.

The nubm35 and nubm37 are usually the best deal.

You pay more for virgin pins, that is pins without solder residue.

Buying from China you take a risk.

 

[additude]

Thanks.

When you say, "Buying from China", do you refer to eBay items that may originate from China, but are sold through eBay, possibly including Amazon, or are you referencing other online sales such as aliexpress where ya can take a chance at receiving a defective item and exchanging or returning it? or maybe both?
I also read on these forums that there is possibly counterfeits as well...maybe....

 

[RedCowboy]

I've only purchased a few of these arrays, well 4 arrays and only 1 had a defect, so I've had a 75% success rate so far.
I haven't seen any obviously counterfeit arrays, all that I bought appear to be legit and I doubt anyone would go to the trouble needed for as few as they sell.

Yes I am talking about items sent from China or a local shipping house working for a Chinese merchant, remember the units are not for sale by the manufacturer to the public so they are likely liberated from the assembly line where the devices they are being installed in are assembled, maybe because of defects ( trash bin salvage ) or maybe sticky fingers or OEM's looking to do a little side business, hence the scratched out #'s ...... so yes, I am not surprised when I get a unit with a defect ( especially tin pin units ), unhappy but not surprised.

 

[additude]

I can say, yep...all the usual stuff to be aware of and concerned about. Thanks.
So, I just ordered a "New" no solder NUBM35, let's see how it goes...

 

[RedCowboy]

Make sure you use heat sink compound when you mount it to your heat sink BEFORE you power it up, the diodes are too close together to run without a heat sink, otherwise you will start burning out the substrate stacks and melting the tiny gold bond wires between them before you know it.

Also remember to protect your eyes when working with any laser over 5mw, it's so very worth it when you make your 1st mistake and thank God you were wearing your laser safety glasses, because everyone will make mistakes in this life.

 

[additude]

I will do. I also ordered a 3" x 3" round aluminum bar and I have Cooler Master Mastergel Pro V2 compound to use. I will secure it with four 6-30 x 1/2 flatheads. Do you think it needs to be electrically isolated?

Safety is a must.... I don't even operate my Nichia '44's without my eye protection.

 

[RedCowboy]

All the ( + ) and ( - ) pins are insulated from the body of the array, so there's no need to isolate the body of the array or your heat sink.

 

[Ricker]

"...they are likely liberated from the assembly line where the devices they are being installed in are assembled, maybe because of defects ( trash bin salvage ) or maybe sticky fingers or OEM's looking to do a little side business, hence the scratched out #'s ..."

Hahah, I often wonder how these are "liberated." I'm half expecting a little piece of rice stuck in a block from a workers lunchbox that he stuffed full from the assembly line.

 

[additude]

I used to work as a manager and test and repair technician on an electronics assembly line for a major manufacturer. All high dollar and precious components are accounted for. Component test failures are turned in and swapped for new replacement components. Memory chips, processors, etc. Work is scheduled in lots. Each lot is supplied with enough components to finish the lot, plus anticipated failures. When a lot is completed, you will know what's short. The only ones doing hands on are the test techs. Assembly is automated inserters.

 

[RedCowboy]

Acme projector may make and sell thousands of units each month, but littleguy projectors is more of a custom shop making specialty projectors for extra large venues or ultra high quality home theaters..... however when littleguy's business gets slow, he may sell some " goods " on the grey market, after scratching out the serial numbers so as not to lose his ability to buy the protected goods.

It's not that the goods are especially dangerous, it's a matter of potential liability that the large goods maker doesn't want to risk.

 

[Ricker]

Yup! And I assume assembly lines in China are slightly different than others.

 

[additude]

Acme projector may make and sell thousands of units each month, but littleguy projectors is more of a custom shop making specialty projectors for extra large venues or ultra high quality home theaters..... however when littleguy's business gets slow, he may sell some " goods " on the grey market, after scratching out the serial numbers so as not to lose his ability to buy the protected goods.

It's not that the goods are especially dangerous, it's a matter of potential liability that the large goods maker doesn't want to risk.

Yep, that is definitely a possible resource option as well. I'm sure littleguy's contract with said supplier states littleguy cannot sell individual components, only components installed in assemblies. It's probably more about littleguy selling a bit on the side regardless of work flow.

Asset inventory on efficient assembly lines in China are no different than they are here in the USA. Matter of fact, we learned a lot about manufacturing efficiency from the Asian manufacturers. It's all based on process flow economics, line of sight manufacturing and just in time inventories. When pennies start getting pinched the focus becomes intensely precise and highly scrutinized.
That's not to say that yeah, theft happens from time to time, but when it does happen, it becomes a zero in razor focus to point of loss. What's probably happening mostly, is that for example, a MLD array is deemed defective when it is not defective and replaced with a good component. Then the supposedly bad component is scrapped and during that scrapping process, those in the know finger the swapped component. That's why most of them have signs of solder.
Then in the field, it's a different story for repairs. Inventories of repair parts, etc. by CSR (Customer Service Repair) techs. "Yep, it's a bad module, gotta replace it. It's gonna be $2K for the repair", when it's actually a fuse in the power supply....

 

[additude]

So, I will just tag this thread instead of starting a new one with this question.
When you are wiring up arrays, what gauge of wire are you using for P/S - Driver to the array?
I've been able to use 1-foot lengths of 22AWG for testing 49V @ 6Aish into 8ohms but I think that's on the cusp of flirting with danger.
Is something more like 20AWG or even 18AWG more appropriate?
Any recommendations?

 

[RedCowboy]

A lot of people here use the high quality silicon multi-strand copper 22AWG because it's nicely flexible and it fits in pairs through the solid copper back halves of our favorite 12mm copper modules, but you can use 18AWG to wire up your array, using bigger wire is no problem, going too small can mean smoke and fire........ not good.

That said I don't see any problem with 18AWG...... now some technical person going by the AWG chart might say you need 16AWG silicon multi-strand copper wire to carry up to 4.5A @ 100V but I would have no issue using 18AWG silicon wire.

Here's a conservative chart, I've pushed wire much harder.

 

[Ricker]

Check out this thread from Shmackitup (Barnett Unlimited.) He's very intuitive with the MLDs and made this badass cordless gun with a NUBM34! He's a great resource and member of the forums.