Question: I attempted to manually clean my printer's print head, and now I'm facing multiple issues. After reassembling, I heard something rubbing and noticed missing small blue plastic pieces. I replaced these with cut hose pieces but it's not working properly. The print head initially spits ink during a head cleaning instead of during a nozzle check and it won't feed paper at all, even though the internal metal bar rolls. I tried reinstalling the printer and its software, but no success. I then turned it off to avoid further damage. When I turned it back on, only the back would turn on, followed by a high-pitched beep after checking the back fuses. I've now ordered a new printer cable and new transistors for my husband to solder, and a fuse from the original supplier. Could these steps address the underlying issues, or should I consider other components?

Answer: Thank you for your detailed message and for seeking help with your printer issues. At BCH Technologies, we appreciate your engagement, especially with our YouTube channel. Your efforts play a crucial role in deepening our collective understanding of printer maintenance and repair.

You've embarked on a thorough approach to diagnosing and fixing your printer, which appears to involve several interrelated issues. Let's address each component you've mentioned:

Printer Cable and Mechanical Assembly Issues: The rubbing sounds and the discovery of missing blue plastic pieces suggest that part of the mechanical assembly may have been compromised during your initial cleaning attempt. Without looking at them, I am not sure what they are. Replacing these parts with cut hose pieces was a creative solution.

The issues with your print head and paper feed suggest that the printer cable, especially if bent, could indeed be a significant part of the problem. Replacing the printer cable is a sensible first step, as a damaged cable could affect data transmission and power supply, leading to the printer behaving erratically.

Fuse and Electrical System: I noticed that your printer is a Model 1390, not an L-1800. The fuse for this model is located at the front; you can refer to the image where I've highlighted this area. It appears that Procolored has rerouted a pair of white wires to bypass the original fuse. I'm unsure if they've added another fuse at the end of these wires or if it's simply been bypassed without additional protection. If the latter is the case, there is a significant risk of damaging the mainboard due to the lack of proper circuit protection. Consequently, the fuse originally on the mainboard is now bypassed and ineffective, with the circuit's integrity depending entirely on what's been done at the end of these white wires.

The fuse blowing and needing replacement indicate an overcurrent or short circuit within the printer. It's good that you’ve ordered a new fuse, but it's also crucial to investigate what caused the fuse to blow in the first place. The installation of bypass wires you mentioned could complicate this, as any improper handling or modifications to the electrical system could lead to more severe damage, such as burning out the mainboard. Ensure that any modifications, like bypassed fuses, are done correctly or restored to their original configurations to prevent further issues.

MOSFETs and Control Circuits: The MOSFETs controlling the power bridge are crucial for the mainboard's functionality. If the printer powers up partially but then fails, it suggests that while the MOSFETs might not be entirely faulty, other parts of the circuit could be. The high-pitched beep could indeed point to a malfunctioning chip or a stalled motor, which aligns with your paper feed issues.

Systematic Troubleshooting: You are correct in addressing the most straightforward fixes first, like the cable and the fuse. However, considering the variety of symptoms, it may also be worth examining other components such as the print head itself, the driver chips, and the entire mechanical assembly for any additional misplaced or damaged parts. The high-pitched sound you're hearing could be due to several factors, such as a malfunctioning chip or a stalled motor. Given that the printer is failing to feed paper, the issue might indeed involve the motor. It would also be wise to inspect the driver chip. There are numerous components to check in this printer. While I concur with the technician that the MOSFETs may not be the issue, I also doubt that the fuse is at fault. Unfortunately, without physically examining the printer myself, pinpointing the exact problem is challenging.

Professional Assistance: Given the complexity of these issues and the potential for further damage, seeking professional help might be advisable if these initial fixes don’t resolve the problems. At BCH Technologies, we offer in-person evaluations and repairs at our local diagnostic facility, and we recommend taking advantage of this service, especially for intricate issues that persist after initial troubleshooting.

Thank you again for reaching out. Your proactive approach to understanding and resolving these issues is impressive, and we are here to support your efforts to get your printer functioning smoothly again. For further assistance, do not hesitate to contact us or visit our YouTube channel for instructional videos that might help with your current printer issues.