Epson ET-8550 Error 031006 After Replacing F1 and F2 Fuses: Correct Fuse Specs, Causes, and What to Check Next

Question:
I have an Epson ET-8550. I replaced the F1 fuse because it was shorted, using a 1A fuse, and it worked for a few restarts. Then the F2 fuse failed. I replaced F2 with the same 1A fuse, but now it keeps blowing repeatedly and the printer shows error 031006. I cleaned the printhead and the sensor board on both sides, and the flex cables appear fine. Is there an exact specification for the F1 and F2 fuses? I measured about 15 to 20 ohms around the fuse area where the scanner and printer side meet on the board. The capacitors also seem fine based on meter checks and a thermal check using a bench power supply.

Answer:

In your case, the most important point is this: the F1 and F2 fuses on the ET-8550 are not the same fuse. They may look similar physically, but they are different in electrical characteristics. These differences are not limited to current rating alone. They can also differ in response speed, surge tolerance, and voltage-related behavior. That is exactly why we offer them as a matched set in this F1/F2 fuse bundle for the Epson ET-8550 and ET-8500 [(https://bchtechnologies.com/products/f1-f2-fuse-bundle-for-epson-et-8550-et8550-et-8500-fix-errors-031004-031005-031006-no-power-issue?_pos=2&_sid=09e2a102e&_ss=r)].

The reason this matters is that replacing either fuse with a generic 1A fuse can allow the circuit to behave in a way it was not designed for. Even if the printer powers up briefly, the wrong fuse may not open at the proper time, or it may open too slowly. When that happens, a downstream component-often an IC, driver circuit, or power-management component-can be damaged before the fuse sacrifices itself. Once that downstream part is damaged, installing another fuse usually does not solve the problem. Instead, the new fuse blows again because the short or overload is still present.

That repeated fuse failure strongly suggests that the issue has moved beyond just the fuse itself. Based on what you described, that is the most likely reason you now keep seeing error 031006. On Epson models in this family, error codes 031004, 031005, and 031006 are commonly associated with startup and hardware initialization faults related to board-level power distribution, scanner/printer communication, or protected circuits that are no longer operating correctly. Since your printer worked only briefly after the first repair and then began repeatedly blowing F2, that pattern is consistent with a damaged downstream board component.

Your cleaning steps were still worthwhile. Cleaning the printhead area, sensor board, and checking the flex cables helps rule out contamination, corrosion, and obvious cable damage. However, when a fuse blows repeatedly, especially after substitution with an incorrect type, the root problem is often electrical rather than cosmetic. A cable may still look fine and yet have an intermittent short. A capacitor may pass a basic meter test and still fail under load. Likewise, thermal checks with a bench supply can help, but they do not always catch partially failed ICs or semiconductors that only misbehave during full startup conditions.

The 15 to 20 ohms reading you found around the fuse area is not, by itself, enough to clear the board. In low-voltage printer circuits, that resistance can still indicate a heavy load path, depending on where exactly the measurement was taken and whether other components were still in circuit. Resistance checks on an assembled board can be misleading because you are often reading through multiple parallel paths. In other words, "not a dead short" does not necessarily mean "safe to power." A circuit can still be faulty enough to pop the fuse once live voltage is applied.

At this stage, the most likely possibilities are:

1. The wrong fuse specification caused secondary damage downstream.
   This is the leading possibility based on your description.

2. There is still an unresolved short in the circuit protected by F2.
   This could involve a power IC, motor driver, scanner-related subcircuit, or another board-level component.

3. A cable or connected module is shorting only under live voltage or during initialization.
   Static continuity checks do not always reveal this.

4. A partially damaged component is drawing excessive current during startup, triggering error 031006 and blowing the fuse repeatedly.

Because of that, simply replacing the fuse again-even with the correct one-may not fix the printer anymore. If a downstream IC has already failed, the correct fuse will simply do its job and open again.

The practical next step is board-level diagnosis using proper tools: a current-limited bench supply, thermal camera or freeze spray, diode-mode comparison, schematic-level tracing if available, and experience isolating printer power rails. This kind of testing usually goes beyond what can be done with a standard multimeter alone. That is why I would strongly suggest professional board repair help at this point.

You can review our mainboard repair service page [(https://bchtechnologies.com/collections/printer-repair-service/products/fast-track-mainboard-repair-l1800-xp-15000-et-15000-wf-7610-7620-wf-7110-wf-7710-7720-et-8550-et-2720-et-2750printer-mainboard-formatter-board-motherboard-troubleshooting-and-repair)]. That page explains the repair cost, supported models, whether to send the mainboard or the whole printer, what is included, what is excluded, turnaround expectations, shipping responsibility, warranty details, and when full-printer repair may be the better option. Please read it carefully before ordering so you know exactly what to expect.

Printer problems like this can be difficult because they are very hands-on by nature. Because of that, we are not able to provide remote troubleshooting, repair suggestions, or step-by-step support for board-level printer repair. We do offer an in-person evaluation and repair option through our local diagnostic and repair service [(https://bchtechnologies.com/printer-repair-service)]. Due to demand, all work is handled on a first-come, first-served basis, and it may take a few weeks before we are ready to receive your printer or board. Our service structure allows repair of either the complete printer or selected parts, with clear instructions on how to proceed. That said, we recognize that our rates may not be the cheapest option. For that reason, we also strongly encourage self-help through online research. A good place to begin is YouTube, including our BCH Technologies YouTube homepage [(https://youtube.com/@bchtechnologies)]. You can use the search icon next to "About" on the right side of the menu bar to look for videos on very specific topics. We get many questions every day asking whether we have made a video on a certain repair. Since we have published videos over many years, using YouTube's search function is often the fastest way to locate the right one. It may also surface useful videos from other channels.

Thank you again for reaching out to us and for supporting BCH Technologies. We truly appreciate your patience, your trust, and your continued engagement with our content.