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Topic: Pro mini fried RAW input (Read 163 times) previous topic - next topic

bpjobin

Hi,

This is my first project here so please bear with me.  :)

It seems that I somehow fried one of my pro minis RAW input. I can still power it on via the 5V VCC input and it'll run basic code correctly. However when I power it through the RAW input nothing happens. Nothing seems physically damaged on the board hence my reluctance to replace the voltage regulator before what's actually broken. Would you guys know a way I could repair this board or am I confined to use it only through the vcc pin at 5V?


Here's the project I'm attempting to build. So far I was able to put it all together on a breadboard (minus the resistor). When I tried to make it more permanent though the board seemed to have shorted out. I have other boards available to replace it but I'd like to prevent such thing from happening again. It was powered through 12V 5A.

I'll take any advice you guys have!

Thank you! :)


jremington

#1
Mar 19, 2018, 03:15 pm Last Edit: Mar 19, 2018, 03:18 pm by jremington
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When I tried to make it more permanent
Please explain what you did.

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I'll take any advice you guys have!
Avoid idiot Fritzing diagrams, as they are usually confusing and misleading. What is the black thing labeled "VREG" and what are the associated pins?

bpjobin

Please explain what you did.
I meant soldering wires directly to pins on the board and on each components the same way it was wired on the breadboard prototype.

jremington

That is what I suspected. You probably have a bad solder connection, or a solder bridge shorting two connections together. Inspect everything with a magnifying glass, and check continuity/shorts with your multimeter.

bpjobin

Please explain what you did.
Avoid idiot Fritzing diagrams, as they are usually confusing and misleading. What is the black thing labeled "VREG" and what are the associated pins?
It's a semiconductor. Model TIP31A.
http://www.datasheetlib.com/datasheet/317801/tip31a_mospec-semiconductor.html

Do you have a better alternative for Fritzing? It was actually meant for future personnel reference.

Thanks!

jremington

#5
Mar 19, 2018, 03:30 pm Last Edit: Mar 19, 2018, 03:35 pm by jremington
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Do you have a better alternative for Fritzing?
A hand drawn schematic, with care taken to properly label components and connections, is almost always better than Fritzing. A simple rectangular box, with labeled pins, works for most modules like Arduino, voltage regulators, etc.

Note that a TIP31A NPN transistor has no relation whatsoever to a "VREG" or voltage regulator, which illustrates my point.

I use professional schematic preparation programs, i.e. LTSpice (free, and also does circuit simulation) or Eagle (which produces circuit board designs). There are many others.

bpjobin

That is what I suspected. You probably have a bad solder connection, or a solder bridge shorting two connections together. Inspect everything with a magnifying glass, and check continuity/shorts with your multimeter.
I did inspect it for shorts due to a solder bridge but could find any. It must be a wiring short then but I've inspected it multiple times and it's wired exactly the same way as the prototype.

I could post a picture to see if you can spot any mistake.

About my question about resurrecting the pro mini? Is it doable?

jremington

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About my question about resurrecting the pro mini? Is it doable?
No idea. They cost $2 on eBay, so I buy a few at a time and have thrown a few away.

ReverseEMF

#8
Mar 19, 2018, 07:02 pm Last Edit: Mar 19, 2018, 07:13 pm by ReverseEMF
Just a possibly related note: The Pro Mini specs [https://store.arduino.cc/usa/arduino-pro-mini] stipulate a max voltage on the Raw input of 12V, but I've damaged several Pro Mini clones by powering them with 12V! In fact, the schematic indicates a max of 16V!!

So, it's weird that my clones have been blowing out, since the official schematic calls for an MIC5205 voltage regulator which is spec'ed to take as much as 16V on it's input (and even an Absolute Max of 20V!)-- so, perhaps the clone manufacturer that sources my Pros is using something different.  I haven't tried this, yet, but maybe you have a similar situation going, and if you have micro-soldering skills, you could try replacing that part.

And, just like your case, I'm still able to power these "fried" Pros from the +5V pin.                                                                                                                                       
                                                                                                                                                           
                                                                                           
The Elevator Goes Up and Up!

Wawa

A ProMini has a tiny 5volt regulator without heatsink.
With 12volt on RAW (V-in) you can't draw any power from a pin (for a LED, etc) without overheating that regulator.
Use a micro-power buck converter set to 6 or 7volt, or set it to 5volt and connect it directly to the 5volt pin.

What are you trying to drive with that TIP31.
A TIP31 with 1k base resistor is fine for driving a single piece of LED strip (as in the Fritzing picture).
But don't try to drive more than one section with it.
Leo..

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