Why Your Printer Won’t Feed Paper After Replacing the Printhead and Carriage: Troubleshooting Feed Issues and Motor Errors

Question:
I recently installed a new printhead and carriage from BCH Technologies and also replaced some transistors. However, now my printer won’t print at all—the paper, which is on a roll, does not move during print attempts. Could this be an installation issue, or is it more likely something wrong with the motherboard? I'm unsure what step to take next.

Answer:

Understanding Printer Motion Axes

Your printer operates with two key axes:

• X-axis: Controls the side-to-side movement of the printhead (known as the carriage return), powered by the CR motor.

• Y-axis: Manages the front-to-back paper movement (the paper feed), powered by the PF motor and monitored by the PF scale sensor.

Since your printhead carriage moves correctly and the issue lies with the paper not feeding, your problem is isolated to the Y-axis or paper feed mechanism.

Potential Causes and What to Check

1. PF Motor and PF Scale Sensor
   The PF (Paper Feed) motor is responsible for pulling the paper forward, while the PF scale sensor ensures precise paper advancement. If either of these components is malfunctioning—especially after major replacements like the carriage and transistors—it could disrupt normal paper feed behavior.

   A misalignment or improper reinstallation of the PF scale sensor, in particular, can prevent the printer from knowing where or when to feed the paper.

2. Mainboard Damage or Faulty Signal
   If you’ve also worked on the transistors or other components on the mainboard, it’s possible that the PF motor signal line was affected. A damaged transistor or PCB trace could prevent the board from sending commands to the motor, essentially “silencing” it.

3. PF Override Board (Roll Adapter Board)
   Since you're using roll paper, another thing to consider is a PF override board (also known as a roll adapter board). These are third-party boards designed to trick the printer into accepting roll paper instead of cut sheets. If misconfigured or defective, the PF override board could interrupt or suppress the page feed signal entirely.

   Try temporarily disconnecting the override board (if applicable) and test the printer using regular cut sheet paper. If the printer feeds normally without the roll adapter, that suggests the third-party board may be the culprit.

4. Firmware Limitations or Communication Glitches
   In some models, replacing components like the printhead or carriage can trigger firmware-level restrictions or calibration errors. Running a full printer reset or firmware recalibration (if your printer allows it) might help reinitialize the paper feed system.

Final Notes on Repairs and Support
Dealing with printer issues often involves hands-on, component-level diagnostics, which are hard to resolve remotely. Because of this, we unfortunately can’t offer in-depth troubleshooting over email or chat. However, we do provide an in-person diagnostic and repair service through our local repair facility (https://bchtechnologies.com/printer-repair-service).

Please note that:

• Repairs are first-come, first-served, and we may need a few weeks to fit you into the queue.

• We can work on full printers or targeted part repairs.

• Our service is not the cheapest option, so we highly encourage DIY troubleshooting when possible.

For DIY help, the best place to start is our YouTube channel homepage (https://youtube.com/@bchtechnologies). Click the search icon next to the “About” tab and enter the issue you're working on. With over nine years of content, we likely have a video that covers your topic—or YouTube may suggest helpful videos from other experts.

Thanks again for your question and your continued trust in BCH Technologies. We're always here to support your repair journey, whether you're watching our videos, shopping for parts, or dropping off a machine. Keep the questions coming!