3 Signs of a Faulty TTO PCB

Thermal printers are essential devices in various industries, facilitating efficient printing of labels, receipts, and other important documents. However, like any electronic component, the PCB (Printed Circuit Board) of a thermal printer can deteriorate over time, leading to functionality issues. In this blog post, we will discuss the top three signs that indicate your thermal printer's PCB might need to be replaced. Recognizing these signs will help you diagnose the problem accurately and take appropriate action.

No Power: The Silent Unit
One of the primary signs of a faulty PCB is when your thermal printer fails to power on entirely. When you attempt to turn on the unit but nothing happens, it's crucial to investigate further. Start by inspecting the touchscreen's ethernet port. If the screen remains unlit and the LED lights on the front of the printer are also not illuminated, it indicates a power supply issue. However, if the ethernet port quickly blinks when power is supplied, it suggests that the touchscreen's power supply unit (PSU) is functioning correctly. In such cases, the fault likely lies with the PCB.

Printing Issues Persist Despite Component Replacements
When your thermal printer consistently fails to print, even after replacing the printhead and printhead cable, it is a clear indication that something is amiss with the PCB. To understand the cause, it helps to consider the flow of energy in the printing process. Energy is sent from the PCB to the printhead through the cable. If the image quality is compromised, it could be due to a fault in any of the three components involved: the PCB, cable, or printhead. However, if the printhead and cable have been recently replaced, the PCB becomes the primary suspect.

Calibration Failure and Unusual Sounds
Printer calibration is an essential procedure that ensures accurate printing and alignment of labels or receipts. If your thermal printer experiences recurrent calibration failures without any apparent reason, it may indicate a problem with the PCB. You might also notice a strange sound accompanying the calibration failure. This sound is typically caused by the motors spinning excessively as they attempt to record a tension measurement. When the measurement fails, the calibration error appears. This combination of failed calibration and unusual sounds serves as a strong indication of a faulty PCB.


Thermal printers are complex devices, and their PCBs play a crucial role in their overall functionality. By recognizing the top three signs that your thermal printer's PCB needs replacement - a silent unit with no power, persistent printing issues despite component replacements, and calibration failures accompanied by unusual sounds - you can effectively diagnose the problem. If you encounter any of these signs, it is recommended to consult a professional technician or contact the printer manufacturer for further assistance. Promptly addressing PCB-related issues will help ensure the continued performance of your thermal printer and minimize downtime.