Two Flashing Lights After Replacing the Power Supply, Printhead Carriage, and Printhead: What Could Be Causing the Printer Errors?

Question

I replaced the power supply, printhead carriage, and printhead on my printer, but I am still getting errors and two flashing lights. I have a picture of the error codes, and I have already spent several days with tech support, but nobody seems to know how to fix it. I am not sure whether the problem is the motherboard or something else. I have tried many different things and still cannot get the printer working. What should I check next?

Answer

Since you mentioned that the printer is showing errors and two flashing lights, but the actual error-code picture was not included here, I cannot identify the exact code from the image. However, two flashing lights after replacing the power supply, printhead carriage, and printhead usually points to one of several areas: carriage movement, printhead detection, cable communication, sensor feedback, or mainboard protection.

The first thing I would check is whether the printer is actually detecting the new printhead and carriage correctly. A new printhead does not always mean the printer will immediately recognize it. If the printhead FFC cable is not fully seated, inserted slightly crooked, reversed, damaged, or contaminated with ink, the printer can throw an error immediately. Even one damaged trace on the ribbon cable can cause a communication failure between the printhead and the motherboard. In some cases, the printer may power on, attempt initialization, and then stop with flashing lights because it cannot communicate with the printhead.

The next thing to inspect is the printhead carriage cable connection on both ends. Many printers use one or more flat flexible cables that connect the printhead carriage assembly to the mainboard. If the locking tab on the connector is loose, broken, or not fully clamped, the printer may behave as if the printhead or carriage is defective. Also check for bent pins, ink residue, corrosion, or burn marks around the cable sockets. If the old printhead failed electrically, it may have damaged the cable or even the mainboard connector.

Because you already replaced the power supply, I would not assume the power supply is still the main suspect unless the replacement is incorrect, unstable, or not matching the original printer specifications. A wrong-voltage or weak power supply can create strange symptoms, but if the printer powers on consistently and attempts to initialize, the issue is more likely downstream: mainboard, carriage movement, printhead communication, or sensor feedback.

The two flashing lights can also be caused by a carriage jam or carriage-positioning problem. Even if the carriage physically moves, the printer needs to know where the carriage is. That depends on the carriage encoder strip and the carriage encoder sensor. The clear plastic encoder strip behind the carriage must be clean, properly seated, and running through the sensor correctly. If it is dirty, scratched, out of its slot, or contaminated with grease or ink, the printer may lose track of the carriage position and stop with blinking lights. Clean the strip gently with water or a mild cleaner on a lint-free cloth, but do not scratch it.

Also check whether the carriage can move freely from side to side when the printer is powered off. It should not feel stuck, grinding, or blocked. Look for anything that may have been left inside the printer during the repair: a screw, piece of plastic, cable routed incorrectly, ink tubing, damper line, or a mispositioned capping station. If the carriage hits an obstruction during startup, the printer may interpret that as a fatal carriage error.

Another important area is the CR motor and belt system. The carriage motor must be able to move the printhead carriage smoothly. If the belt is too loose, too tight, off-track, or slipping, the printer may fail during initialization. Also check the carriage rail. If the carriage rail is dry, dirty, or has too much resistance, the printer may stop and flash the error lights. The carriage should glide smoothly without binding.

Since you replaced the printhead, it is also possible that the original printhead failure damaged the motherboard. This is especially common when a printhead shorts internally. A shorted printhead can blow a fuse, transistor, driver circuit, or printhead-control component on the mainboard. In that case, replacing the printhead alone will not fix the printer because the board can no longer drive or communicate with the printhead properly. If the printer gives a printhead-related error immediately after startup, even with a known-good printhead and known-good cables, the mainboard becomes a stronger suspect.

Look closely at the mainboard for small surface-mounted fuses. Some Epson-style boards, for example, have tiny fuses labeled with markings such as F1, F2, or similar. If one of these fuses is open, the printer may power on but fail to drive the printhead or carriage electronics. You would need a multimeter to test continuity across those fuses. Do not bypass a fuse unless you know exactly why it failed, because bypassing it without fixing the root cause can cause more serious board damage.

If your printer uses a waste ink counter or service error system, two flashing lights can sometimes indicate a waste ink pad or maintenance error. However, because your issue appeared after replacing the power supply, carriage, and printhead, I would first focus on hardware communication and initialization failures rather than assuming it is only a waste ink counter. Still, if the printer model supports a service utility, it may be worth checking the exact error code through the manufacturer's adjustment program or diagnostic tool.

For the error codes shown in your picture, the exact meaning depends heavily on the printer model. Some codes point to a carriage return error, some point to a printhead temperature or communication error, some point to paper feed or encoder failure, and some point to a mainboard-related fatal error. Since the actual codes were not visible in the text of the question, I would not want to misidentify them. If the code is a general "fatal error," that usually means the printer detected a hardware condition it cannot recover from during startup. If the code is a carriage error, then focus on the CR motor, belt, encoder strip, carriage rail, and carriage path. If the code is a printhead error, then focus on the printhead, FFC cables, printhead lock, carriage board, and mainboard fuse or driver circuit.

Here is the order I would check things:

First, reseat all flat cables, especially the printhead and carriage cables. Make sure they are straight, clean, fully inserted, and locked. Second, inspect the cables for ink damage, cracks, creases, or burned contacts. Third, check the encoder strip and carriage sensor. Fourth, confirm the carriage can move freely and nothing is blocking it. Fifth, inspect the capping station, pump, and wiper area to make sure the carriage is not hitting anything during startup. Sixth, test the mainboard fuses with a multimeter. Seventh, if everything else checks out, consider that the mainboard may have been damaged by the original failed printhead.

One thing I would be careful about is repeatedly powering the printer on and off if there is a possible short. If a cable is inserted incorrectly, or if the replacement printhead is defective, repeated startup attempts can damage the mainboard further. Before continuing, I would inspect every cable and connector carefully. A reversed or misaligned FFC cable can instantly create a serious fault.

Also, replacement printheads and carriage assemblies are not always guaranteed to be good, especially if they are used, refurbished, or aftermarket. A defective replacement printhead can produce the same symptoms as the original failed printhead. If possible, compare the part numbers and physical layout with the original part. Make sure the replacement printhead is truly compatible with your exact printer model.

At this point, yes, the motherboard is definitely a possibility, but I would not jump to it until the cables, encoder system, carriage movement, and fuses have been checked. Many "bad motherboard" symptoms are actually caused by a loose FFC cable, dirty encoder strip, jammed carriage, or damaged connector. However, if the printer had a printhead short before the repair, then the mainboard may already have been damaged before the new parts were installed.

Addressing printer issues can be a complicated affair because many of these problems require hands-on testing. For that reason, we are not able to provide remote troubleshooting, personalized repair suggestions, or step-by-step support for individual 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 you can drop off your printer. Our services are structured to repair either a complete printer or specific parts, with clear instructions on how to proceed. However, we understand that our rates may not be the most economical option for every customer. For that reason, we strongly recommend using self-help resources and online research whenever possible. You can begin by checking YouTube or visiting our YouTube homepage at BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Use the search icon next to the "About" tab on the right-hand side of the menu bar to search for videos related to your specific printer model, error code, carriage problem, printhead issue, or motherboard repair. I receive dozens of questions every day asking where to find videos on specific topics. Since we have created repair videos over the past nine years, it is difficult to remember every single one, so YouTube's search function is usually the fastest way to locate the most relevant video. YouTube may also suggest helpful videos from other repair channels.

Thanks again for contacting us and for supporting BCH Technologies. I hope this gives you a clearer path for checking the printer instead of replacing parts blindly. In your case, I would focus first on the printhead cable connections, encoder strip, carriage movement, and mainboard fuses before deciding that the motherboard must be replaced.