How to spot an LM561C diode

Growroom Design
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#1

on another forum it was discovered nearly every major chinese PCB manufacturer was using diodes other than advertised. it’s very easy to tell the difference visually. the biggest clue is the incorrect diodes will have a very visible black circle while on the LM561C it will be nearly invisible. there are other ways to tell, like the shape of the corners, the connectors etc.

diodes.png659×544 307 KB

one particular manufacturer (jeff @ hansion) after being called out was very quick to apologize and assure people that it was an accident and actually LM561B+ - supposedly very close in efficiency etc. however the chinese are known to cut corners and rip people off (including each other, so maybe the ‘accident’ was just jeff himself getting ripped off)
there is no way of knowing what the diode actually is without testing or taking it apart at that point, and if they’re going to rip you off on parts which are so obvious i wonder what other corners they’re cutting on the parts you can’t see, like other components or copper weight.

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#2

At Least it’s still a Samsung Diode that is very close in efficiency though… It could be much worse an not even a samsung diode at all and a chinese knock off… https://news.samsung.com/global/samsungs-new-mid-power-led-package-line-up-lm561b-offering-superior-performance-and-higher-quality-light-color-for-premium-luminaires

#3

yeah well the guy says its a samsung diode… but he also said it was an lm561c to begin with so there’s no way of knowing at that point without testing… it might not even be samsung at all as epistar and other manufacturers make identical ones. i imagine bottom bin lm561b+ is not very close to top bin lm561c

#4

LED is such a craze.

Not surprised someone is already trying to take advantage. :disappointed:

99%

#5

[quote=“legalcanada, post:1, topic:7561”]
jeff @ Yeah if it is a bottom bin vs top bin then there will be a slight difference but the LM561B+ Puts out almost the same lumens as the c 190l per watt vs 200 only 10 lumens difference. I’m just saying if I could get the LM561B+ board for a lot cheaper than the LM561C then I would jump on it for the negligible difference in output… Do you know who carries the LM561B+ boards by chance?:slight_smile:

#6

mufue and hansion i think are 2 of the bigger chinese pcb manufacturers but again it’s taking a risk and a leap of faith

#7

Yeah, But if it is a Samsung LM561B+ It will be fine with me. Thanks @legalcanada

#8

This is the company I plan on buying from. https://m.alibaba.com/product/60726279664/Meijiu-new-design-quantum-boards-288pcs.html?spm=a2706.7843299.1998817009.18.JUnGLx
There’s only one other company with a better track record and they’ve got a 1000 piece minimum.

#9

just make sure to ask for macro shots of the diodes, meijiu was another company passing off other diodes as lm561c. and if you play your cards right, you might be able to get that 1000min order company to send you a few boards for free as a sample :wink:

1 Like
#10

Which forum - have a link?

#11

Member on riu just confirmed well enough imo that meijiu are legit lm561c s6

#12

The diodes with the dot are Samsung LM561B+ chips. One generation removed from the C chips. Not “fakes” or “counterfeits”. Genuine Samsung chips, introduced in April 2016. About 5% less efficient at test currents, almost no difference at typical operating currents. Otherwise same specs, binning and production quality.

It’s another RIU tempest in a teapot IMO, and @legalcanada seems determined to stir it at OG. It is a concern, but much is being made of very little, mainly to throw shade on various players and ethnic groups, and sow a lot of FUD to benefit the chief advertiser on that website. I’ve used older Samsung chips, 561Bs, for 2 years with great success, they inspired me to develop SolStrips in the first place.

The B+ diodes are popping up because Samsung has cranked back production of the C chips in 3500K as it shifted into production of its newest LM301 chip. I was told that inventories of C chips have already stabilized and shouldn’t be a problem going forward.

I have a few of the X2 strips using B+ chips in the 3500K CCT (noted in the listing description). They perform exactly like the C chip strips in every way. You can’t distinguish them when lit side by side with the C chips.

More 3500K X2 strips with LM561C chips are already on their way and should be in stock by the end of the month. All of the 2700K and 5000K strips, X1 and X2 versions, are using C chips. The stock issues have only effected the 3500K chips. Going forward, we are committed to using only the latest generation LEDs available in our strips. But rest assured, if you’ve got a dot on your chip, you’ve got an excellent, genuine Samsung top-quality LED that will perform at the very highest levels for a long time.

-b420

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#13

the dots also appear on similar epistar 5630 diodes iirc, and it’s useful information for anyone considering buying off alibaba/ebay

@anon32470837 it was the thread which @Skiball linked

edit: looks like osram and other brands 5630s as well

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#14

Here’s another thought I had about those diodes. Do lm561c s5 have the black dot? That could be what they are correct? Honestly even if that were the case screw it at that point good enough imo

#15

i dont think so for any lm561c. how did the user on RIU confirm meijiu for the 561c, just visually for the black dot? i have a feeling even if you’re getting 561cs off alibaba or ebay it’s most likely bottom bin, or not top bin at least. i’m not sure if a PAR meter would be reliable enough to tell, might need sphere testing to really know. there’s gotta be a reason HLG and chilled both get their diodes placed in USA and it probably has to do with no recourse against chinese companies

#16

it looks like the picture that user posted did show a visible black dot on the 561C s5… i wonder where he got it from

#17

Ya that’s the point I made on possibly being s5. Also to my understanding only hlg only places 3000k chips in the US. Now I have a theory of why that is but no proof. Just from observations of the market and with a lit bit of knowledge I have of Chinese business practices.

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#18

Digikey so it’s legit, so b+ and s5 are the same?

#19

hmm i’m not sure, i’d like to track down an early purchaser of a quantum board s5 version to see if theres are similar. i wonder if it has something to do with CRI or color spectrum, does that affect how thick the phosphorus coating is on the diode? or is it just a different color of phosphorus they use?

so maybe jeff was telling the truth when he said it was b+ version, because if he wanted to lie he could have just said it was lm561c s5 if that’s the case. i wonder if digikey sources direct from samsung or a chinese distributor

#20

I don’t know honestly. But if the guy can’t tell the difference between the 4sure lm561c s6 and the chip he has under a microscope it’s good enough for me