Epson ET-8550 DTF V2 Conversion Error 031004: PF Encoder Disc, PF Sensor, and Cable Checks

Question

I recently performed a DTF V2 conversion on my Epson ET-8550 and installed the upgrade board that resolves the page-size issue and controls the ink and CIS motors. After the conversion, the printer keeps showing error 34004. I checked for paper jams but did not find anything. I also installed the drag chain. What should I try next?

Answer

First, I want to clarify the error code. You mentioned 34004, but on the Epson ET-8550, this may actually be 031004. These two can be easy to confuse depending on how the error is displayed. Error 031004 is commonly related to the PF path, which means the printer is having trouble detecting or controlling the paper feed movement. "PF" stands for paper feed, and this system includes the PF motor, PF encoder disc, PF sensor, PF feedback cable, and related mechanical movement.

Since you already checked for paper jams and did not find any, I would focus next on the PF encoder disc and PF sensor area.

The first thing I would check is whether the PF encoder disc is properly installed inside the PF sensor. The encoder disc must sit between the two sides of the sensor, not outside of it. The sensor reads the fine markings on the encoder disc as the paper feed mechanism moves. If the disc is not positioned inside the sensor slot, the printer cannot read movement correctly. When that happens, the printer may think the PF system is stalled, blocked, or out of sync, even if there is no actual paper jam.

After a DTF V2 conversion, drag chain installation, or internal cable routing work, it is possible for the PF encoder disc or sensor area to be disturbed. Even a small misalignment can cause the printer to throw a PF-related error. Look closely at the disc and make sure it is not sitting beside the sensor, rubbing against the sensor housing, bent, dirty, or blocked by a cable.

Next, check the PF sensor FFC cable orientation. For this model and setup, I would make sure the PF sensor's FFC cable is installed with the silver contact side facing left and the blue stiffener side facing right. If the FFC cable is reversed, partially inserted, or not locked evenly, the mainboard may not receive the PF sensor signal correctly.

When checking the FFC cable, do not only look at whether it is inserted. Remove and reseat it carefully if needed. Make sure the cable goes in straight, the contacts are clean, and the locking tab is fully secured. A cable that is inserted at a slight angle can still look connected but fail to transmit the signal properly.

Then check the PF feedback cable connection on the mainboard. Make sure it is securely installed and fully seated. During conversion work, especially when installing an additional control board for DTF functions, cables can become slightly loose. A loose PF feedback cable can produce the same kind of error because the printer cannot confirm that the PF motor and encoder system are moving as expected.

Also inspect the PF cable for damage. Look for creases, torn traces, scratched contacts, or pressure marks from the drag chain. The drag chain is helpful for managing tubing and cable movement, but if it creates too much tension or restricts motion, it can interfere with the carriage or paper feed system. Make sure the drag chain has enough slack and does not pull against any sensor cable, motor cable, tubing, or moving assembly.

Since the error appeared after the DTF V2 conversion, I would also check for anything that may be mechanically preventing normal movement. Even if there is no paper jam, the printer can still report a PF-related error if the mechanism feels resistance. Check for tubing, wires, brackets, screws, or the drag chain interfering with the carriage path or paper feed path. Move the carriage and related assemblies gently by hand with the printer powered off, and feel for any unusual binding or obstruction.

Here is the order I would suggest checking:

1. Confirm whether the error is actually 031004 rather than 34004.

2. Check that the PF encoder disc is placed between the two sides of the PF sensor.

3. Make sure the disc is not outside the sensor slot, bent, dirty, or rubbing.

4. Verify the PF sensor FFC orientation: silver side toward the left, blue side toward the right.

5. Reseat the PF sensor FFC and make sure it is straight and fully locked.

6. Check the PF feedback cable on the mainboard and make sure it is securely installed.

7. Inspect all cables and tubing affected by the drag chain installation.

8. Make sure the drag chain does not restrict movement or pull on cables.

9. Look for any mechanical resistance in the paper feed path or carriage movement.

If the printer was working before the conversion and started showing this error afterward, the most likely cause is something disturbed during the installation rather than a failed motor or failed mainboard. In many cases, this kind of error comes down to the encoder disc being outside the sensor, the FFC cable being reversed, or the cable not being fully seated.

Addressing printer issues can be a complicated affair because many problems require hands-on inspection. For that reason, we are not able to provide remote troubleshooting, detailed repair guidance, or ongoing repair support for individual printer cases. We do offer an in-person evaluation and repair service through our local diagnostic facility, BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]. Due to high demand, this service is handled on a first-come, first-served basis, so it may take a few weeks before we can receive your printer for drop-off. Our services are structured to repair either a complete printer or specific parts, with clear instructions on how to proceed. However, we understand that our rates may not be the most economical option for everyone. Because of that, we highly recommend using self-help resources and online research whenever possible. You can start by checking YouTube or visiting our YouTube channel homepage at BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Use the search icon next to "About" on the right-hand side of the menu bar to search for specific topics. I receive dozens of questions every day asking for videos on particular repairs, and after creating videos for more than nine years, it is difficult to remember every single one. YouTube's search function is usually the most efficient way to find the right video, and it may also suggest helpful videos from other channels.

Thank you again for contacting us and for supporting BCH Technologies. I hope these checks help you narrow down the source of the 031004 / PF path error and get your ET-8550 DTF V2 conversion moving in the right direction.