Pi IoT printers starts up with smoke - not good!

[franswaas]

When finished building and wanted to test my Pi IoT printer there was smoke coming out of after plugging it in. I know it's a thermal printer, but smoke didn't seem ok... unplugged to see that the pi T-cobbler print got burned.

I double checked the wiring with the instuctions on http://learn.adafruit.com/pi-thermal-printer/soldering, but can't see what went wrong. I'll attach images of the damaged cobbler, maybe you can tell me what went wrong.

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Could it be a soldering issue? I used the power supply provided (only changed the 8-cable going to the wall socket because of different plug, I live in the Netherlands), so that should be OK.

[adafruit_support_bill]

Definitely a short circuit of some kind. It looks like you fried the trace from the 5v pin. My guess is that you plugged the ribbon cable on to the RPi GPIO header backwards. That would connect the 5v pin directly to the GND pin.

Make sure that pin 1 of the cobbler is connected to pin 1 on the Pi (closest to the SD card). Usually, the cable edge corresponding to pin 1 has a stripe on it. It will only plug in one way on the cobbler, but there is no key on the Pi to prevent you from plugging it in reversed.

[franswaas]

Mmm... I'm 100% sure I placed the cobbler correctly on the pi. Didn't use a cable, as I followed the instructions and connected the T-shape board with the sockets soldered on the underside of the board directly to the pi (where 5V pin is indeed first in the corner near the SD card, I checked with the wiring instructions and available photos).

Maybe I should mention that the LED-ring of the push button was giving light (despite me frying the 5V trace).

Do you have any other suggestion at what I could have been doing wrong? Want to make sure not to make the same mistake when I get a new Pi T-Cobbler board...

[adafruit_support_bill]

Maybe I should mention that the LED-ring of the push button was giving light (despite me frying the 5V trace).

The trace was your fuse. Once fried, the led would be powered normally.

Do you have any other suggestion at what I could have been doing wrong? Want to make sure not to make the same mistake when I get a new Pi T-Cobbler board...

It looks like you have all the right connections. Before powering anything up, test for any continuity between 5v and GND. It's probably worthwhile doing that test with the fried cobbler first to find out what went wrong with that. You can solder a jumper to replace the burnt trace. Test it both on and off the Pi.

[adafruit_support_rick]

You had the Cobbler plugged in like this, right?

Is it possible that you had it shifted by one or two pins, left or right? That's easy to do with the unshrouded header on the Pi.

[franswaas]

Started measuring with a Volt-meter. Only logical explanation seems to be that I shifted the cobbler indeed to the left of the pi (to the right I would have seen the pins), as all the rest seems OK. Will try with a new cobbler (but must first order one...). Thanks for your support!

[adafruit_support_rick]

That's kind of what I figured - one pin to the left would connect GND to 5V.

[franswaas]

A new T-cobbler fixed the problem!
I now have a fine working IoT printer, thanks for helping to find out what I did wrong!