Continuity Issues with 5V 10A supply + LEDs

I'm running a set of ~150 LEDs controlled by my Arduino Uno. When I connect my soldered prototype board to a 5V 10A power supply (a cheapo Amazon one) my voltmeter checking continuity changes from reading around 640 to beeping. I fried another power supply of similar build before, so I want to avoid doing so again! The circuit runs with a lower amp supply, but is not enough to run the whole setup with full brightness.

The arduino is powered separately than the LED lights by a USB wall socket. I had this running on a breadboard fine, so perhaps there is a short-circuit somewhere. I'm not too clear on what the volt meter readings mean when using continuity setting.

If you disconnect the power supply from the circuit and connect the DMM to the power input of the circuit, DMM + to circuit +, what does the DMM read? Then what is the reading DMM + to circuit - and DMM - to circuit +?

Then the same readings on the power supply, by itself?

Post a schematic of the circuit.

With the power supply disconnected:

The reading of the DMM + to circuit + and DMM - to circuit - is 648.
If I swap this, so DMM + to circuit - and DMM - to circuit +, the reading is 541.

Checking the power supply + to - there is a reading of 50 (and continuous beeping).

Will have to draw a schematic as I haven't made one yet.

If you do not have a program for drawing schematics, this tutorial may be of interest.

Sounds to me you are measuring the output impedence of the supply? What are you trying to measure with the DVM in continuity mode?

Thanks, I'll try to draw one up this evening.

I'm trying to see if there is a short circuit, or why the previous supply began smoking. As I understand, continuity mode is useful for demonstrating that there is a short circuit - i.e. by it beeping. Perhaps there is another issue I should consider or another test I could run?

Don't buy cheapo supplies from Amazon or eBay, they are seldom safe or meet the published output specs. Get something like a Meanwell(*) branded supply from a trusted stockist, don't risk the dangerous junk sold by the unscrupulus, mains supplies need to be safe.

(*) I've seen these recommended on youtube and CNC forums several times as dependable and affordable supplies. There are other big name brands out there of course (and rip-off versions of them too).

I agree that cheap supplies aren't ideal, however I had it working with a cheap supply on a breadboard before. With a more expensive supply I might melt it anyways with a short...

Here is the schematic (to the best of my abilities):

you have GND connected to -5V. SO if your GND is connected to the PSU GND you have a short circuit.
Is the gadget top right on A0 a microophone module?

Pretty good !!
My suggestion is to check some parts of the circuit independently. Disconnect the PS and check that it is simply providing 5v (with the multimeter as a voltmeter) on the points that you connect it to the system.
Now leaving the PS disconnected, check with the continuity setting to see if there is a short between 5v+ and GND, or any of the DATA lines and GND or 5v+.
If that all checks out, start checking all connections from source to destination. All GND everywhere needs to be connected, (check with the UNO as well) all 5v+ needs to be connected etc.
Don't do any continuity checks with the power supply on ! and even just connected may cause issues and false readings.

These are more or less normal readings.

as i said, you should check the PS to see if it provides the correct voltage.

Oh yeah, the Capacitor spec is actually 1 for each strip, but it should work fine the way you have it.

Very well drawn scheme. I guess -5V of PSU is actually GND. I do not see anything suspicious in the scheme.

Why do you power the Arduino Uno and the WS2812 LED strips separately? In my opinion, this could be a problem because in the end both power supplies are connected to the AC network. Wouldn't it be better to use only the powerful power supply and connect the Arduino Uno and the LED strips to it? They need only 5 volts.
150 WS2812 LEDs at full brightness and white color consume about 9 amps of current. Your power supply is at the limit and it would be better to have some power reserve. You can try powering the Arduino from a power bank to isolate it from the AC mains. However, I think that if you use only 1 power supply there should be no problem.

Yes, it's the adafruit electret microphone amplifier. Electret Microphone Amplifier - MAX4466 with Adjustable Gain : ID 1063 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits

The idea was to connect the ground of the arduino to that of the PSU, as advised for the neopixel best practices Best Practices | Adafruit NeoPixel Überguide | Adafruit Learning System

Thanks Deva, I'll give this methodical testing approach a go today. Probably the best way to find an issue that I haven't done yet!

I was wondering about this... but I only had a few capacitors of this strength so I took a bit of a short cut. As I understand, the capacitor is there to mitigate any large surge when powers given to avoid damaging the components.

This is a good point! I just realised the arduino has a power pin in, so you don't have to rely on the USB or DC socket. I thought though that Arduino prefers 6-20V input.

I also want to send 3.3V rather than 5V to the electrik microphone amplifier because it reduces noise.

7-12v on the Vin, but the 5v pin takes what it says on it.

i suppose you can just use the 3.3v pin

So, everything is up and running! After doing these last checks and not finding any continuity where there wasn't supposed to be, I plugged it in: there was no smoke and the LEDs worked as anticipated. I think that the previous PSU started smoking because of an intermittent loose connection. All soldered and should be fine now, and will take into consideration the circuit modifications. Thanks everyone for the tips!

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