Mini Thermal Printer Not Printing Correctly/At All

[mantismei]

Hi, I'm fairly new to all of this and I've been having a couple of issues with my printer:
1: the test prints out ~12cm of blank paper
2: following the instructions from https://learn.adafruit.com/mini-thermal ... controller , I loaded A_printertest onto my Arduino and this was what it printed instead:

IMG_8345.JPG (73.13 KiB) Viewed 213 times

This is my set up. The Arduino is connected to my laptop USB port, I have it set at 5V. Baudrate at 19200 like what the Selftest sheet lists.

IMG_8346.JPG (177.59 KiB) Viewed 213 times

Another thing I tried: I connected the printer to a 9V battery while disconnected from the Arduino + while connected with the laptop-powered Arduino. Either way, the light started blinking faster, but it refused to print altogether. I also tried to switch RX and TX, but that seemed to make it print out even less, so probably not the solution here.

All help is appreciated!

[adafruit_support_mike]

The thermal printer wants at least 1.5A of current. It takes a lot of power to run the resistors on the thermal print head.

In the photo, it looks like you're getting power from the Arduino, which in turn gets power from a USB cable. That's known to fail:

https://learn.adafruit.com/mini-thermal ... nter/power

Try powering the printer separately, using at least a 2A @ 5V power supply.

[mantismei]

Thanks for this, I didn't realize the Arduino power source could be a problem. All is running smoothly now!

[adafruit_support_mike]

Yep.. it takes a lot of current to make the array of resistors in the thermal print head heat up.

Glad to hear things are working for you. Happy hacking!