Why Your Epson EcoTank ET-8550 Won’t Power On After Replacing the Printhead—And How to Fix It

Question: I recently changed the nozzles/printhead on my brand-new Epson EcoTank ET-8550, and now it won’t turn on. Could this be related to an incorrect printhead connection or a power supply issue?

Answer:

Common Causes and Fixes for ET-8550 Power Failure After Printhead Replacement

1. Incorrect Printhead or Ribbon Cable Connection

Yes, this is a likely culprit. The Epson ET-8550 performs hardware integrity checks at startup. If the printer detects any abnormality—especially something that could damage internal components—it will not power on.

Here’s what to look for:

• Loose or Half-Inserted FFC (Flat Flexible Cables): These ribbon cables must be pushed in firmly and evenly.

• Wrong Orientation: Ensure that the shiny metal contacts face the correct direction. A reversed cable will not just fail—it might cause shorts.

• Bent Pins or Damaged Connectors: Scrutinize connectors under bright lighting. Even slight misalignment can trigger a fail-safe.

• Internal Short Within the Printhead: A defective printhead (even a new one) could short the motherboard and prevent power-on.

Fix: Reopen the unit and carefully inspect the cable terminations at both ends. Straighten any crimps and reinsert with precision. Ensure no metal shavings, ink, or debris shorten the contacts.

2. Power Supply, Blown Fuses, or Mainboard Fault

If you powered the printer during the swap or if a cable was misaligned during startup, this could have blown key protection components:

• F1 and F2 Surface-Mount Fuses: These miniature but critical fuses on the mainboard protect against short circuits. If one or both are blown, the printer will appear dead.

• Capacitors near the Power Circuit: Look for bulging, leaking, or blackened components. These are signs of electrical stress or damage.

• Burn or Scorch Marks: Especially around voltage regulator chips or the main DC input rail.

Fix: Use a multimeter to test F1 and F2 for continuity. If either reads “open,” it has blown and must be replaced. Visually inspect the board under magnification for component damage. We offer a mainboard diagnostic and repair service if you're unsure how to proceed.

You can learn more here: BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service).

3. Test Power Without the Printhead

A helpful test: try disconnecting the printhead cables entirely and attempting to power on the printer. If it powers up now, the printhead is likely internally shorted.

If it turns on without the printhead:

• Replace the printhead.

• Double-check the cable connections before inserting a new one.

Suggested Action Steps

1. Disconnect and carefully reseat all ribbon cables between the printhead and mainboard.

2. Check F1 and F2 fuses with a multimeter.

3. Visually inspect for damaged capacitors or burn marks.

4. Try powering the printer without the printhead installed.

5. If nothing works, consider sending your mainboard to BCH Technologies for evaluation.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. So, we cannot 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. It may take a few weeks to get your printer to drop it off. Our services are structured to repair a whole printer or specific parts, with clear instructions on how to proceed. However, we acknowledge that our rates aren't the most economical. Thus, we highly recommend that you resort to self-help via online research. You can start by checking out YouTube or visiting our YouTube channel's homepage (https://youtube.com/@bchtechnologies). Look for specific videos using the search icon next to "About" on the right-hand side of the menu bar. I receive dozens of queries every day asking about videos for specific topics. Having created videos over the past nine years, it's challenging to remember every single one. Therefore, using YouTube's search function would be most efficient. Plus, YouTube might suggest relevant videos from other channels that could assist you.

Thanks again for your patience and for your question. We appreciate your continued support of BCH Technologies and are here to help however we can.