Epson ET-8550 Motherboard Fuse Repair: B15, F1, and F2 Fuse Identification for Error Codes 031004, 031005, 031006, No Power, or Freezing

Question

I am working on an Epson ET-8550 motherboard repair and noticed that the board shows a fuse labeled B15, but I do not see B12. Did you mean B15 instead of B12? I do not want to start the repair until I confirm this, especially because the parts look very similar. In your video, you mentioned that F1 and F2 look identical but are not the same, so I want to make sure I identify the correct fuse before replacing anything.

Answer

Yes, you are correct. It should be B15, not B12. That was a typo on our part, and it has now been corrected. Thank you for catching it before starting the repair.

The correct product page is here: 3-in-1 Combo B15, F1, F2 Fuse for Epson ET-8550 / ET-8500 [https://bchtechnologies.com/products/3-in-1-combo-b12-f1-f2-fuse-for-epson-et-8550-et8550-et-8500-fix-errors-031004-031005-031006-no-power-freeze?_pos=2&_sid=02f07e754&_ss=r]. Although the URL may still contain the older wording, the correct component identification is B15, along with F1 and F2.

If you look at the second picture on the product page, it clearly identifies the locations of B15, F1, and F2 on the ET-8550 / ET-8500 motherboard. That picture should be your main visual reference when locating the components on the board.

This fuse set is commonly associated with Epson ET-8550 and ET-8500 mainboard problems such as:

• Error 031004

• Error 031005

• Error 031006

• printer freezing

• printer not powering on

• printer partially powering on but not completing startup

• sudden shutdown after a short attempt to initialize

These symptoms can happen when one of the protection components on the motherboard has failed. The fuses are there to protect the circuit, so if a downstream component shorts or draws too much current, the fuse may open instead of allowing more serious board damage. However, replacing the fuse alone does not always solve the root problem. If the original cause is still present, the new fuse may blow again immediately.

For the ET-8550 motherboard, the important correction is:

B15 is the correct fuse location. B12 was a typo.

You are also right to be cautious about F1 and F2. They may look identical physically, but you should not assume they are interchangeable without confirming their placement and rating. On a motherboard, many surface-mounted components can look the same from the outside, even when they serve different parts of the circuit. A fuse, resistor, capacitor, diode, or zero-ohm jumper may have similar size and color, but they are not automatically the same part.

Before replacing anything, I recommend the following careful approach:

First, use the product photo as a map and confirm the silkscreen label on your actual motherboard. Look for the printed markings near the component itself. If the board marking says B15, then you should treat that location as B15.

Second, do not rely only on appearance. F1 and F2 may look the same, but their circuit locations matter. Replace each part only with the matching part intended for that exact board position.

Third, test the fuse before removing it if you have a multimeter. Set the meter to continuity mode. A good fuse should normally show continuity. A blown fuse will usually show open circuit. If B15, F1, or F2 is open, that can explain startup, no-power, freezing, or error-code behavior such as 031004, 031005, or 031006.

Fourth, inspect the surrounding area before soldering. Look for burned marks, liquid damage, corrosion, lifted pads, cracked components, or damaged ribbon cable connectors. The ET-8550 motherboard is sensitive, and a shorted cable, damaged printhead, or damaged peripheral component can cause the replacement fuse to fail again.

Fifth, be very careful with heat. These are small surface-mounted components. Too much heat can lift the copper pads from the motherboard. If the pads lift, the repair becomes much more difficult than a simple fuse replacement. Use proper flux, avoid excessive force, and do not scrape the board aggressively.

Sixth, after replacing the fuse, do not immediately reassemble everything and assume the printer is fixed. Recheck for shorts if possible. If the fuse failed because of a connected component, such as the printhead, scanner, carriage cable, or another board circuit, the new fuse may blow again as soon as power is applied.

In short, yes, you should be looking for B15, not B12. The typo has been corrected, and the second picture on the product page identifies B15, F1, and F2 clearly. Your caution is correct, especially because F1 and F2 look identical but should still be treated as separate components in their proper locations.

Addressing printer issues can be a complicated affair because many of these repairs require hands-on testing, board inspection, and careful component-level work. For that reason, we are not able to provide remote troubleshooting, repair suggestions, or individualized repair support for printer repairs. 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, we operate on a first-come, first-served basis, so it may take a few weeks before your printer can be scheduled for drop-off. Our services are structured to repair either the whole printer or specific parts, with clear instructions on how to proceed. However, we understand that our rates are not the most economical option for everyone. Therefore, we strongly recommend self-help through online research whenever possible. You can begin by searching YouTube or visiting our channel homepage: 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 look for specific repair topics. I receive dozens of questions every day asking for videos on specific subjects, and after creating videos for the past 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 YouTube may also suggest helpful repair videos from other channels.

Thank you again for pointing out the B12/B15 typo and for checking before starting the repair. That careful approach can save a motherboard from unnecessary damage.