Blew out an Arduino Pro Mini 5v with 12v power supply

I am setting up an Arduino Pro Mini 5v (https://www.amazon.com/gp/product/B015MGHLNA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) to control a strip of WS2811 RGB LED lights (https://www.amazon.com/gp/product/B01CNL6K52/ref=oh_aui_search_detailpage?ie=UTF8&psc=1).

The power supply is 12v 8A (https://www.amazon.com/gp/product/B01MZGNJA5/ref=oh_aui_search_detailpage?ie=UTF8&psc=1), the lights are 12v, and I thought the Arduino could handle 12v on the RAW input. I think I was wrong. After connecting it, the part circled in the picture below popped and smoked and my heart sank. If I use my continuity meter across the circled piece, it beeps. If I test that same piece on a different board, it does not beep.

If I put a 7808 voltage regulator in between the 12V power supply and the Arduino, will that fix my problem? Is there another, better solution? This whole this is going to be part of a chandelier, so I really need to be able to make it work off the single 12v power supply.

Is my other board totally shot, or will it work with just regular 5v input?

If you need more information, please let me know. Thank you

Where else did you post this question?

That capacitor failed and became a wire. You will have to remove it and should almost certainly replace it.

Look at the Pro Mini board layout and schematic to find out what capacitor you need to replace it.

Yes, running your Arduino on 8V (even better: 7V) will cause less heat in the voltage regulator. You could also regulate your 12V down to 5V and power the board through a Vcc pin.

The cap is C19 on the schematic diagram.
A smoothing cap from RAW (12volt in) to ground.
The ProMini should still work without it, but the charred remains could be shorted so you should remove them.
Just use a solderint iron, and swipe off the remains (without force).
You could use an external smoothing cap from RAW to GND. The original one was 10uF.

Could be that they have used caps with a lower voltage rating on the clones (e.g. 10volt).
If so, then you need to drop that 12volt with an external regulator to e.g. 9volt.
Or go directly to 5volt, and connect to the VCC pin.
Leo..

You probably hooked up the 12V supply with reverse polarity. Don't repeat.

aarg:
You probably hooked up the 12V supply with reverse polarity. Don't repeat.

Doubt that.
C19 is a non-polarised ceramic cap.
Something else would have gone up in smoke.
Leo..

Wawa:
Doubt that.
C19 is a non-polarised ceramic cap.
Something else would have gone up in smoke.
Leo..

On my schematic, it's a 10uF polarized cap (probably tantalum).

True on the Eagle files.
All the tantalum caps I have seen have some + markings, but you could be right there.
Maybe the cap was mounted reversed in the factory.
Leo..

thank you for the responses.

prior to hooking this up, i double-checked that the +/- were in the right spot, and i just went back and confirmed it.

the caps on all 5 boards are all installed the same way, so i'm relatively sure it wasn't put in backwards. however, i have caps with 3 different markings on them entirely (not making me happy about my purchase)
GA7A
A7C
C106

the capacitor that popped is labeled: GA7A, and from what i've found online (couple different datasheets) this would be a 4V, 10uF cap made in 01/2013 or 01/2017 (although, i could be reading it wrong). i took that cap off and hooked it up to the computer via USB and everything seems to be in working order. i can write my sketch to it and the board is responsive to input, so i don't think the entire board is a lost cause. i tried to solder a 10uF cap back in place, verifying - to -. now the board doesn't do anything when i plug it in to 12v, but it still works on the 5v side.

I'm going to get a 5v voltage regulator and install that and re-wire it to the vcc pin.

as far as the other 2 caps... well, i can't find much information on what the other 2 values mean.

thanks agin.

The date codes aren't a reliable ID. What would be interesting is to check the orientation against a data sheet. I'm sure the data code has a standard orientation that effectively identifies the polarity. It could be just a part failure, why not just spend $2 on another board?

I see on the PCB that both 106 caps (the number suggests 1 uF, not 10 uF - so skimping on voltage rating may be expected, too) have a rectangular marking on one side, an angled one and a line on the other. Looks like polarization marking.

Maybe best use a 7805 or similar 5V regulator and connect it to the 5V pin.

I see on the PCB that both 106 caps (the number suggests 1 uF, not 10 uF - so skimping on voltage rating may be expected, too)

106 is 10uF… The caps in the photo do seem to have a white band on the top end; indicating polarity, and probably that they are polarized caps. Ceramic caps also tend not to have ANY markings on them.
Tantalum caps are relatively infamous for failing spectactularly in the face of relatively brief over-voltage conditions or they could be under-spec’ed (10V is a common voltage.)

Ah, missed a zero :slight_smile:

The other day I had a 20V tantalum smoke after being connected to 12V for a long time (correct polarity, it just spontaneously failed). That was using a 5V-12V boost converter.

Was there a lot of ripple on the 12V supply?

For me - not that I'm aware of. Nothing else connected to it, its a simple USB plug with 12V output, boost converter built into the USB connector.
Spontaneous combustion :slight_smile: