(Boarduino) Voltage Regulator getting hot

Hi - this pertains to the Boarduino - but I can’t find the forum link on the adafruit site - maybe it is a generic enough question though.

I built a circuit using the Boarduino and the MAX7219 chip. Have done this a number of times before. This time I am not getting the expected response from the 7219 and the Boarduino voltage regulator is getting hot enough to not want to hold my finger on it. It still functions though- am able to upload sketches, blink pin 13 etc.

I’ve checked all my traces with a continuity checker looking for shorts, etc. Found none. The only thing I can think of is that I fried the 7219 and it is causing the voltage regulator to heat up.

So I guess in the category of “General Things That Can Go Wrong” for $200 - what is the significance of a hot voltage regulator (oh - feeding this with a 9v wall wart power supply). Or more simply… “Why do electronic things sometimes get really hot”? :wink:

Like the saying, "follow the money", for heat problems you must "follow the current".

You need to measure total current consumption and if higher then other similar modules, then you need to find the specific power branch that is consuming higher then normal current. It will lead you to the problem.


dumb question - but can I do this by using a multimeter on the voltage regulator and other components to see what they are drawing?

(I am not completely without clues - just don’t always have the right ones :slight_smile: )

Sounds like the MAX7219 is drawing a lot of current and the regulator is getting hot as a result. Put your multimeter in DC current measuring mode and put it in series with the power supply going to the MAX7219 to see how much current its drawing.

If your multimeter can measure current then you can read the total amount by connecting the multimeter in serial with the power lead, but you may need to cut a wire on the wall wart to do this. Another approach is to meausure the current flowing through the 7219 power pin (multimeter between this pin and 5volts).

But first, measure the voltage on your wall wart, many produce voltages higher than the rated amount. Ideally you want one that produces around 8 volts DC, everything above this gets converted into heat.