April Board SD Card Holder getting warm/hot

Alright, so I got an April board form Adafruit, I plugged in a 9V battery and after a few minutes, I realized that there was a jumper that need to be on “BAT” for the Vin rather than USB. Well, I’m running it still now not he 9V and I’m able to do the “Hello World” blink. For the LED I was using a 3V LED, so I just skipped the resistor from Pin 9 to GND on the board, but I figured I should do things right, so I swapped out the 3V with a red 2V and put a 68 ohm resistor in.

So the problem is, the SD socket is getting pretty warm/hot while running. What’s the deal? Did I burn something out just by having the Vin jumper to USB, if so, that’s a pretty sad designed board.

Edit: I’m using the USB now and it still get hot to the touch.

Edit #2: So I checked the schematics & board design and there shouldn’t have been any issue with the way I wired things up. I’m reading 3.273V on the 3V3 to GND pins. With the USB it’s 5.02V to GND. I’m still not understanding why it’s warm/hot to the touch. I sure hope someone from Electric Imp can shed some light on this. Very frustrating to bust these out of their boxes only to have this issue.

VIN seems to be directly connected to the usb connector, so I think it is meant to only get 5V max.

To connect a battery you should solder it to the two pads marked with + and -, and move the jumper over to BAT.

However, it should not damage the Imp.

I have made one Imp get very hot too, but that was after shorting an output to gnd.

Remove your 9V and go back to using the USB (put the jumper back in).
Then wait and see if it gets hot.
Basically, you’re going back to square one and seeing if anything is strange.
If it doesn’t get hot, you know you’re OK and can re-evaluate your power source.

The tutorial says to use a 330ohm resistor. You are drawing more current with the 68 ohm… probably more than the pin wants to handle. Skipping the resistor is bad for the imp and the LED.

If you ever saw 5v on the 3.3v/GND pins, then you have likely partially fried the imp. It still working, but getting hot (even when running at 3.3v) is consistent with how silicon can behave when partially fried. It probably won’t last very long from this point.

Hugo, I should have clarified. The 5V I saw was when I was plugged in using USB for power measuring from Vin to GND. I know that the 3V3 regulator is pretty precise so I was happy to see the 3.273V was 3V3 to GND.

Once the initial frustration subsided, I just ended up ordering another set from Amazon. Still kind of frustrated at how easy this thing is to burn up. The only possible thing I can think of at this point was driving too much current from Pin9 when I had an LED hooked up. One thing I would like to see is something as simple as the forward voltage for the led they have in the initial tutorial. I find it funny they make sure to state 330 ohm resistor but don’t mention the forward voltage. For a typical 2V red led that I have, that’s only 6mA which is not that much at all considering most call for 15-20mA. Just my observation.

Edit: Once I receive my new set, what risk would I be running testing a new Imp on a possibly bad board or a bad imp on a new good board? Just wondering if in finding out the culprit if I’ll end up destroying my new stuff.

You would have problems blowing it by connecting things that draw current to the IO pins. Worst case you’d damage a single pin driver, not the whole thing.

But… bear in mind that the imp is not a 5v arduino; the silicon is fabricated in a much smaller silicon process and so is more sensitive to overvoltage or reverse voltage, either on the power rails or on IO pins.