Why Does My Galaxy DTF Printer Keep Blowing Bypass Boards? Troubleshooting Board and Printhead Compatibility

Question:

I own a Galaxy DTF station printer, and I’m having an issue with the bypass board. It keeps blowing. I've already replaced it twice. I’ve also installed a new printhead cable, motherboard, circuit board, and power cable, but the bypass board continues to fail. What could be causing this?

Answer:

Understanding the Problem: Why the Bypass Board May Be Failing

When a bypass board “blows,” it typically means that it's either short-circuiting or drawing too much power. Given that you’ve replaced the motherboard, circuit board, printhead cable, and power cable, the root cause likely lies in compatibility or incorrect wiring, particularly around the printhead connection.

Many DTF printers marketed as Galaxy, L1800 clones, or similar models are based on either the Epson L1800 or 1390 architecture. However, to cut manufacturing costs, some brands use a modification board—commonly known as a bypass board—that sits between the motherboard and the printhead. This board allows an L1800 motherboard to drive a different printhead, such as an L805, which is less expensive.

Key Troubleshooting Steps

✅ Step 1: Identify Whether You’re Using a Modified Setup

• Check if there’s a small green circuit board on the printhead carriage. This is often a conversion board that adapts the signal for an L805 head.

• Even though your printer is labeled “L1800,” the printhead might actually be L805, and the bypass board is handling signal conversion.

✅ Step 2: Test Without the Bypass Board

• Disconnect the bypass board and plug the cable directly into a true L1800 printhead.

• This test will help isolate the problem. If the system works without the bypass board using a genuine L1800 printhead, it likely means:

  • The bypass board was needed only for L805 compatibility.

  • The bypass board is not faulty on its own but is blowing due to incompatibility or overload in the signal conversion process.

✅ Step 3: Check Printhead Compatibility

• Confirm what printhead your machine is using. If it’s actually an L805, installing a real L1800 printhead and removing the bypass board altogether might resolve the issue permanently.

• This avoids unnecessary translation and voltage regulation that the bypass board introduces.

Why the Bypass Board Fails Repeatedly

If your printer uses an L805 printhead through a bypass board originally designed for an L1800 system, you’re forcing that board to manage complex signal and voltage conversions. Any slight irregularity—such as a loose cable, a tiny surge, or poor grounding—can fry the board.

You’ve done well to replace other components like the motherboard and cables. However, if the printer was never meant to run with that specific printhead and board combination, the only lasting solution is to match the printhead to the motherboard—ideally by switching to a true L1800 printhead.

Addressing printer problems like this often requires detailed inspection and physical testing. As such, we’re unable to provide remote support or one-on-one troubleshooting services. However, we do offer in-person diagnostic and repair services through our local repair facility. You can learn more or schedule a drop-off by visiting our Printer Repair Service page (https://bchtechnologies.com/printer-repair-service). Please note that due to high demand, we operate on a first-come, first-served basis, and it may take a few weeks before your unit can be evaluated. While our services may not be the most budget-friendly, they are designed to be transparent and structured—whether you're repairing a whole printer or just a component.

We strongly encourage customers to also explore self-repair by utilizing free resources on our YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon next to “About” on our channel page to find videos on L1800, L805, and DTF-specific troubleshooting. With hundreds of videos published over the years, the YouTube search tool is often the fastest and most effective way to find help.

Thank you again for your trust in BCH Technologies. We hope this helps you resolve the bypass board issue and get your printer back up and running.