Troubleshooting Two Solid Red Lights on an Epson L1800 After Replacing the Printhead and Motherboard

Question:
I recently purchased a replacement printhead for my Epson L1800 from a third-party supplier. After installation, it immediately fried the motherboard. I replaced both the printhead and motherboard with new components. Now, when I turn the printer on, the green lights are on, but the two red lights on the front panel stay solid (not blinking), the printhead doesn’t move, and the ink pump isn’t functioning. My computer also won’t recognize the printer, so I can’t see any error codes. The seller is advising me to purchase a new power supply, switch, and motherboard again—but I’m hesitant, as I don’t believe those are the actual issues. What should I do next?

Answer:
Thank you so much for contacting us—and I sincerely apologize for the delay in getting back to you. I know how frustrating and urgent these printer failures can be, especially when you're investing in parts and not getting the expected results. At BCH Technologies, we always strive to respond thoughtfully and thoroughly, and we truly appreciate your support and engagement—especially on our YouTube channel (https://youtube.com/@bchtechnologies). Your questions help us refine our content and expand our technical knowledge base.

Let’s dive into your L1800 issue.

What the Two Solid Red Lights on an Epson L1800 Mean

When both red lights on the Epson L1800 remain solid (not blinking)—and there's no movement from the printhead or activity from the ink system—it usually points to a critical hardware failure, not just a simple consumables warning (like ink or waste pad reset). The fact that the printer also does not connect to your laptop confirms a deeper system issue.

This behavior is different from blinking patterns, which indicate more recoverable or software-level errors. Solid red lights combined with no USB detection often mean the printer is not completing POST (Power-On Self-Test), which happens when key hardware components fail to initialize or communicate.

Possible Causes and What to Check

You've already replaced the motherboard and printhead—smart steps—but there are still a few core components that could be at fault or contributing to a cascading failure.

🔌 1. Power Supply (Power Box)

This is a likely culprit, especially if the original printhead shorted and caused a chain reaction. A faulty or unstable power supply can damage other parts, even new ones. Before buying a new one, use a multimeter to check that the voltage output matches the printer’s required spec (usually printed on the board or housing). Any variation—even brief spikes—can cause protection circuits on the motherboard to shut down.

🔄 2. Faulty or Incomplete Wiring

Check all cable connections—particularly:

• Ribbon cables from the motherboard to the carriage/printhead.

• Power wires from the power supply to the mainboard and ink pump motor.

• FFC cables (Flat Flexible Cables) that might have been misaligned, pinched, or inserted upside down.

Make sure nothing is shorted, crimped, or slightly off-center. One misaligned pin can prevent the system from starting up properly.

🔧 3. Damaged USB Interface or Driver ICs

If your computer isn’t detecting the printer at all, and you’ve ruled out cable or port issues, it's possible the USB controller on the motherboard is fried—or, less commonly, that there's a corrupt EEPROM or firmware glitch preventing boot.

Try a different USB cable and a different computer, just to rule out simpler causes before assuming it's a board-level failure.

🔬 4. Printhead Short Circuits

It’s rare, but some aftermarket printheads have shorted circuits internally. When installed, they can damage the motherboard—or draw power in a way that causes the system to shut down or enter a fail-safe mode. If this happened again, it might explain why your new motherboard and printhead show no functionality.

If possible, remove the printhead and power the printer on without it. If the printer passes POST (the printhead moves or the red lights change), the head may be faulty.

A Word of Caution About Buying More Parts

You're right to be cautious. If your current power board outputs the correct voltage and there's no obvious short in the wiring, there’s no reason to keep replacing parts blindly. The "buy another full set of components" advice is often given as a catch-all fix, but it's not cost-effective and may not solve the root issue.

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). Due to high demand, we operate on a first-come, first-served basis, and it may take a few weeks before your printer can be evaluated. We can repair either the entire printer or specific parts—whichever you prefer—with clear communication throughout the process. That said, we know our rates might not fit every budget. So, we recommend starting with self-help, including tutorials on our YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon near the "About" tab to find specific videos. With nine years of content, the search bar is the fastest way to locate guides—even from other creators YouTube recommends.

Thanks again for reaching out. We hope you're able to resolve this without unnecessary expenses, and we’ll be here if you need expert support.