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Therma Printer - print intensity
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Therma Printer - print intensity

by janolobos on Fri Mar 12, 2021 7:24 pm

I have followed all the tutorials of the mini thermal printer but I have problems printing QR codes, they are unreadable, as shown in the attached image. They have some other library that allows you to print QR codes to some function that allows you to obtain a better printing of images ...
Thank you...
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image (1).png
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Re: Therma Printer - print intensity

by janolobos on Thu Mar 18, 2021 6:31 pm

I have also tried the Python library and even the text and bar codes of the test page do not print correctly...

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Re: Therma Printer - print intensity

by adafruit_support_carter on Thu Mar 18, 2021 6:52 pm

That looks like a power supply issue. What are you using to power the printer?

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Re: Therma Printer - print intensity

by janolobos on Thu Mar 18, 2021 7:18 pm

adafruit_support_carter wrote:That looks like a power supply issue. What are you using to power the printer?


I have used a 5v 2000mA adapter and a 12v 2000mA adapter connected to a DC-DC converter (like the one in the picture) regulated at 7.5v
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DC-DC 3A.png
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Re: Therma Printer - print intensity

by adafruit_support_carter on Thu Mar 18, 2021 7:25 pm

Is there something requiring that power arrangement? Can you just connect the 5V power supply directly?
https://learn.adafruit.com/mini-thermal ... nter/power

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Re: Therma Printer - print intensity

by janolobos on Sat Mar 20, 2021 10:33 am

adafruit_support_carter wrote:Is there something requiring that power arrangement? Can you just connect the 5V power supply directly?
https://learn.adafruit.com/mini-thermal ... nter/power

as I said, connect the printer to a 5v 2000mA adapter, attached image of the adapter
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Re: Therma Printer - print intensity

by janolobos on Sat Mar 20, 2021 10:37 am

Also, increase the size of the image to test if the QR readers could read it, but the image is not readable
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Re: Therma Printer - print intensity

by janolobos on Sat Mar 20, 2021 4:49 pm

One important thing is that I have not been able to update the printer fumware, with the software provided by Adafruit
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Re: Therma Printer - print intensity

by adafruit_support_carter on Mon Mar 22, 2021 10:30 am

Sorry, still confused about how the printer is being powered.

Is the 5v 2000mA adapter being connected to the printer directly? Or is it the 5v 2000mA adapter being connected to the DC-DC converted and then to the printer?

And why is there a secondary power supply? (the 12v 2000mA adapter)

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Re: Therma Printer - print intensity

by janolobos on Tue Mar 23, 2021 5:11 pm

adafruit_support_carter wrote:Sorry, still confused about how the printer is being powered.

Is the 5v 2000mA adapter being connected to the printer directly? Or is it the 5v 2000mA adapter being connected to the DC-DC converted and then to the printer?

And why is there a secondary power supply? (the 12v 2000mA adapter)


I connect the 5v 2000mA adapter directly ... In another test, connect the 12v 2000mA adapter, connect it to the DC-DC converter and regulate it to 8.5v and connect that voltage to the printer to test if increasing the voltage improves the print quality....
it's clear now?
I think it is not a hardware problem, including the adapter, because if you check the images, the impression is clearer in some lines and not in others.

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Re: Therma Printer - print intensity

by adafruit_support_carter on Tue Mar 23, 2021 6:09 pm

Increasing the voltage does help in cases where the printing is dim. 5V is the minimum. But bumping up to 9V does seem to help in these case:
https://learn.adafruit.com/mini-thermal ... nter/power

Do you know how much current the DC-DC converter is rated for? Is it able to pass the full 2A from the 12V supply?

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Re: Therma Printer - print intensity

by janolobos on Tue Mar 23, 2021 6:32 pm

adafruit_support_carter wrote:Increasing the voltage does help in cases where the printing is dim. 5V is the minimum. But bumping up to 9V does seem to help in these case:
https://learn.adafruit.com/mini-thermal ... nter/power

Do you know how much current the DC-DC converter is rated for? Is it able to pass the full 2A from the 12V supply?


Yes, the converter supports up to 3000mA...

Please do not insist on looking for a problem with the adapter ... If you see the photos, you will notice that in the print there are lines that are of better quality than others, I do not think that is produced by the power supply, since the source delivers a continuous voltage and does not change from one line to another line.

You can answer other questions that have arisen from this problem ...? Why can't I update the printer's firmware with the software you provide? the printer I received has version 2.19

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Re: Therma Printer - print intensity

by adafruit_support_carter on Tue Mar 23, 2021 7:26 pm

Why can't I update the printer's firmware with the software you provide?

Are using the software linked here?
https://learn.adafruit.com/mini-thermal ... -1825755-2
If so, see text above link.

Have you tried doing a test print yet? If so, how did it look?
https://learn.adafruit.com/mini-thermal ... first-test

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Re: Therma Printer - print intensity

by janolobos on Tue Mar 23, 2021 9:09 pm

adafruit_support_carter wrote:
Why can't I update the printer's firmware with the software you provide?

Are using the software linked here?
https://learn.adafruit.com/mini-thermal ... -1825755-2
If so, see text above link.

Have you tried doing a test print yet? If so, how did it look?
https://learn.adafruit.com/mini-thermal ... first-test


Yes, I use the application that you indicate....
please I need some real help ... I already tried all the tutorials and suggestions I found on the Adafruit website ... Please read the previous posts

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Re: Therma Printer - print intensity

by adafruit_support_carter on Tue Mar 23, 2021 9:26 pm

OK, as indicated, that software linked is provided without any support and is for use at your own risk.
If you'd like to risk it, you can revert/change the firmware using this tool that is from the manufacturer. We haven't tried it. It's completely utterly unsupported and you may break your printer. We won't replace it if it stops working due to a firmware change!


Printing a self-test page will be useful for a few reasons. We can compare the general quality of that print to the QR code print. It also typically has a readout of the actual power supply voltage seen by the printer, which might be useful information.

This is still, most likely, some form of power issue.

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Please be positive and constructive with your questions and comments.