How to Diagnose Epson ET-8550 Error Code 031006 After Incorrect Printhead Installation

Customer Question:

After watching your video on converting mesh dampers to nipple dampers on the Epson ET-8550, I attempted to reinstall the printhead. However, I may have inserted the FFC (Flat Flexible Cables) incorrectly. Initially, the printer wouldn’t power on. I then corrected the cable placement, and the printer turned on but displayed error code 031006. Based on your video, I tested the fuses on the motherboard and found that fuse F1 appears to be the issue. I’ve ordered a new fuse from your website. My question is: Since only fuse F1 was damaged, is it likely that the motherboard is still safe, or could it have been damaged as well?

Answer:

Understanding Error Code 031006

The 031006 error typically indicates a fatal hardware error, often caused by an improper connection or damage to the printhead or FFC cables. This code is notorious for being ambiguous—it doesn’t always point directly to the source of the problem, but it nearly always involves the printhead circuit.

From your description, it appears that you initially reversed or misaligned the FFC cables during the reinstallation of the printhead. Unfortunately, incorrect cable orientation can lead to an immediate short circuit, especially on sensitive lines carrying power. In such cases, it's very common for fuse F1 on the motherboard to blow as a safety measure to protect other components.

Is the Mainboard Likely Safe?

The fact that your printer was able to power on and display 031006 after the fuse incident is a very positive sign. This suggests that the motherboard (mainboard) was not entirely compromised and retained some basic functionality. If the motherboard had suffered extensive internal damage, it likely wouldn’t even turn on or complete its initial boot phase.

That said, blown fuses can sometimes signal deeper issues, especially if voltage fluctuations traveled to other components. Replacing fuse F1 is a smart first step—and if that resolves the power flow without additional error codes beyond 031006, you may have escaped broader board damage.

But What About the Printhead?

Here’s the more sobering part: in cases like this, the printhead is usually permanently damaged. These components are highly sensitive to both voltage misrouting and reverse polarity. If even one signal or power pin is misaligned or reversed during reinstallation, the internal circuitry of the printhead can be irreparably harmed. That’s why even though your mainboard might have survived, the printhead is almost certainly nonfunctional.

Additionally, before installing a new printhead, please check the condition of your FFC cables. If they are crimped, burned, or degraded in any way, they could damage your replacement part too. Always replace damaged cables and confirm orientation using reference marks or documentation.

Final Recommendations

• Replace fuse F1, which you've already ordered from us—good move.

• Once replaced, try powering on the printer again without connecting a printhead first to see if any different errors emerge.

• Test your FFC cables thoroughly.

• When ready, install a new genuine or compatible ET-8550 printhead using the correct orientation.

• Monitor for any signs of overheating, abnormal noise, or repeating error codes.

Important Service Disclaimer

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. So, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We offer an in-person evaluation and repair service via our local diagnostic facility (https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first-come, first-served basis, and it may take a few weeks before your printer can be dropped off.

Our services are structured to repair either the whole printer or specific components, with clear instructions on how to proceed. However, we acknowledge that our rates aren't the most economical. We strongly recommend starting with self-help resources, such as researching issues on YouTube (https://youtube.com/@bchtechnologies). Use the search icon next to "About" on our channel to look for specific topics. We've created hundreds of videos over nine years, and YouTube’s search function is the best way to find relevant content—often even from other helpful creators.

Thank you again for your thoughtful question and for being part of our technical community. We wish you the best of luck with your Epson ET-8550 repair, and we’re always here to support your journey in any way we can.