Epson ET-8550 DTF Conversion Printer Won't Turn On? Common Causes After Printhead Modification

Question

After watching the Pro-Level ET-8550 DTF Conversion: Modify the Printhead - Complete Course (Part 2) video, I completed the modification on my printer. However, after finishing the conversion, the printer no longer powers on.

Before I start retracing all my steps, I wanted to ask if there are any specific issues or common mistakes that could cause the printer to stop turning on after this modification. Is there anything in particular I should check first?

Answer

Yes-this situation actually happens quite often when people bring partially converted ET-8550 printers to us. When a printer does not power on after the DTF conversion, the issue is usually related to a short circuit, cable connection problem, or fuse failure on the mainboard.

Below are the most common causes we see.

1. Ink Leakage During the Nipple Conversion

The most common cause is related to the printhead nipple conversion.

During this modification, the printhead is removed and reinstalled. If the printhead screws are not tightened properly, the printhead may not seal correctly. When the system is later primed, ink can leak down from the printhead area.

Unfortunately, this leaked ink can travel downward inside the printer and reach the mainboard, which may cause a short circuit.

Once a short occurs, the printer may:

• Fail to power on completely

• Blow one of the mainboard protection fuses

• Appear completely dead

Because this scenario happens frequently, I redesigned the newer version of the conversion course so that the mainboard is temporarily placed outside the printer during the modification process, reducing the chance of ink leaking onto it.

I am also working on an improved gasket design to help reduce the risk of ink leaks around the modified printhead assembly.

2. Check the Mainboard Fuses (F1 and F2)

If the printer does not power on after the modification, the first diagnostic step is to check the mainboard fuses, specifically:

• F1 fuse

• F2 fuse

These are small protective fuses designed to prevent further damage if a short occurs. If ink leakage or a wiring mistake creates a short, these fuses will typically blow.

Testing them is straightforward:

1. Remove the printer casing.

2. Locate the mainboard.

3. Use a multimeter in continuity mode.

4. Test F1 and F2 for continuity.

If either fuse shows no continuity, it has blown and must be replaced before the printer can power on again.

3. MOSFET and Driver Circuit Damage (Less Common)

Fortunately, in most cases the damage stops at the fuse level. I rarely see MOSFETs or printhead driver circuits burn out in this situation.

However, if the fuse replacement does not restore power, the next components to check would be:

• MOSFET driver transistors

• Voltage regulators

• Driver ICs

These components control power delivery to the printhead and other subsystems.

4. Control Panel Ribbon Cable Installed Incorrectly

Another surprisingly common issue is related to the control panel cable.

The ET-8550 uses very small-pitch ribbon cables, and during reassembly it is easy to:

• Insert the cable slightly crooked

• Not fully seat the connector

• Insert the cable backwards

If the control panel cable is installed incorrectly, the printer may fail to initialize or appear completely unresponsive.

Carefully check that:

• The cable is fully seated

• The connector latch is closed

• The cable orientation is correct

5. Review the Conversion Steps

Since you are planning to retrace your steps, pay particular attention to these areas:

• Printhead mounting screws

• Ink tube routing

• Ribbon cable connections

• Mainboard wiring

• Ink leaks around the capping station or printhead

Even a small drop of conductive ink can cause electrical issues inside the printer.

Diagnostic Video for Checking the Mainboard

I will also be releasing a detailed video showing how to diagnose these problems quickly while the printer is open.

You can already see the process of checking the board in this video:

Diagnosing Printer Mainboard Fuse and Electrical Issues
(https://youtu.be/RMCq5wXQNlI)

This guide demonstrates how easy it is to access the mainboard and test the protection fuses.

Updated Version of the Conversion Course

The video you referenced is actually part of the first-generation conversion design.

For the latest version of the ET-8550 DTF conversion process, including improved procedures to prevent these issues, please see the updated course playlist here:

ET-8550 DTF Conversion Course Playlist (Latest Version)
(https://www.youtube.com/playlist?list=PLcfraABWWFgl-bkCV9Ws34-EKRHgt0Jjy)

The newer version includes several improvements designed to reduce the risk of ink leaks and electrical damage during modification.

Addressing printer issues can be a complicated affair due to the hands-on nature of many printer problems. Because of this, we're not able to provide remote troubleshooting or repair guidance for individual printer repairs. However, we do offer in-person diagnostic and repair services through our repair 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, and it may take several weeks before a drop-off slot becomes available. Our services can cover either full printer repair or individual component repair, and we provide clear instructions for sending equipment in for service. That said, we recognize that our repair rates may not always be the most economical solution. For that reason, we strongly recommend exploring self-help options through online research. A good starting point is YouTube or the BCH Technologies YouTube channel homepage (https://youtube.com/@bchtechnologies). You can use the search icon next to the "About" tab on the right side of the channel menu to find videos related to your specific repair topic. I receive dozens of questions every day asking whether we have videos on particular problems. After creating videos for over nine years, it's difficult to remember every single one, so using YouTube's search feature is usually the fastest approach. Additionally, YouTube may recommend helpful videos from other creators that could also assist with your repair.

Thank you again for reaching out and for watching our videos. We truly appreciate your support of BCH Technologies and your interest in learning these advanced printer modification techniques.