faded print via thermal printer

Hello, I have bought Thermal printer: QR-701, from ali-express.
I have attached the printer to Arduino UNO like this sketch:

vh - 5v,
gnd - gnd
RX - PIN 6
TX - PIN 5

And I've uploaded this code from Adafruit_Thermal API on github.(the libaries are added successfully)

And this is the results:

also the print is very slow, for the piece of paper that I've pictured for you took at least 45Seconds.

is this because of something I did wrong? or the product is damaged.


How much current does the printer data tell for the printer?
The first thought is that it is a power issue.
Have You measured that 9 volt during the print test?
Any timing for the signals to the printer?

I wonder where the graphics data come from (slow device?), how many bytes and how fast they are transmitted to the printer (baudrate?).

I have replace the power supply and its work now, thanks!