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I recently bought two 40A, 5V power supplies (Letour) for 990 WS2812B LEDs. Each LED strip (3.3 of them total) is rated for 5V, 20A each. However, when I tested the voltage of both power supplies they were just over 12V.

Is there something wrong in how I am measuring this? It seemed to have worked for the vast majority of people on Amazon and there was no option to purchase a 12V version, so I'm assuming this is a 5V supply.

I definitely don't want to risk blowing my LEDs, and I feel like a step down board would be overkill. Better to return it and err on the side of caution?

Apologies if this is a no-brainer and the company sent me the wrong type somehow, but that would be really inconvenient if it is the case.

This is the link to the supply: https://www.amazon.ca/gp/product/B01HJBEKO4/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

I have also attached a photo of the data sheet.

enter image description here

enter image description here enter image description here

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    \$\begingroup\$ lakerice - Hi, Please link to the manufacturer's datasheet for these power supplies. You mention Amazon - an Amazon seller's page doesn't count as a proper datasheet, but please link their page too. Can you also please add a photo showing the model number markings on these PSUs. Thanks. \$\endgroup\$
    – SamGibson
    Commented Nov 2, 2021 at 1:57
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    \$\begingroup\$ @lakerice Add a datasheet, please. An amazon link isn't enough. \$\endgroup\$
    – Hearth
    Commented Nov 2, 2021 at 2:09
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    \$\begingroup\$ There is a possibility that it needs some kind of minimum load to maintain regulation. Do you have a resistor you could put on there across the output terminals to see if it helps? Or maybe a 12V lightbulb or something? I am not saying I find this likely. Just something to try to see if it makes a difference. Anything that can survive 12 V and draw a little bit of power from the supply. \$\endgroup\$
    – user57037
    Commented Nov 2, 2021 at 2:25
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    \$\begingroup\$ The reviews dont inspire confidence. \$\endgroup\$
    – Passerby
    Commented Nov 2, 2021 at 3:08
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    \$\begingroup\$ Unfortunately, even the good Chinese supplies like MeanWell have counterfeits and imitators that use similar logos MingWei, MenWael and such like. If there is no official store, then authorized distribution is best. \$\endgroup\$ Commented Nov 5, 2021 at 2:09

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I don't see anyway this could be anything but a wrongly labeled power supply. It's supposed to have overvoltage protection which should have tripped in any case.

That does not bode well for the QC and the legitimacy of any safety approval markings it may or may not have. I see no marking with a file number that can be verified.

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  • \$\begingroup\$ I agree. I'm sure that's what it is. \$\endgroup\$
    – lakerice
    Commented Nov 5, 2021 at 1:45
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Your multimeter indicates low battery. You can't trust the measurement, unless you have verified it measures correctly even with a low battery.

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  • \$\begingroup\$ I bet 10 € this is the problem. \$\endgroup\$
    – winny
    Commented Nov 2, 2021 at 11:58
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    \$\begingroup\$ Tested it with a fresh battery...still registers 12.4V \$\endgroup\$
    – lakerice
    Commented Nov 5, 2021 at 1:44
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It may need a decent load on it to start regulating properly. Given that it seems to be outputting 12V, then a 12V filament lamp would be ideal. For example a 12V halogen lamp, or automotive lamp.

If the voltage then drops to 5V then it it only usable with an appropriate load applied.

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  • \$\begingroup\$ I tested it with 150 WS2811 LEDs and it was fine. I tested again with the multimeter and it was still 12.4V. So I got a few lemons :p \$\endgroup\$
    – lakerice
    Commented Nov 5, 2021 at 2:05

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