How to Fix Blank Printing and Maintenance Box Errors on Epson ET-3750 After Deep Cleaning

Question: I recently inherited an Epson ET-3750 that had been sitting unused for several months. I reconnected a red and black signal cable behind the control panel and deep cleaned the printhead using a syringe and cleaning fluid. I also replaced the maintenance box and ran a Power Cleaning cycle, but the printer still shows the maintenance box as full, and no waste ink has collected. It continues to print blank pages. I'm concerned the waste ink line might be clogged and hesitant to run a Power Ink Flush. What should I check next?

Answer:

Thank you for contacting us, and I truly apologize for the delay in getting back to you. I completely understand how time-sensitive and frustrating printer issues can be—especially when you’ve already spent time replacing parts and carefully performing maintenance. We aim to provide the most thoughtful, specific, and technically sound guidance possible. At BCH Technologies, we're grateful for your engagement and continued support—especially for our YouTube channel (https://youtube.com/@bchtechnologies). Your input helps us refine our resources and serve the printer community more effectively.

Let’s take a deep dive into what’s likely going on with your Epson ET-3750 and how to proceed.

Reconnected Signal Cable: What It Affects

You mentioned reconnecting the red and black signal cable behind the control panel. That wire typically handles display communication or control panel input, so while it’s essential for user interaction, it doesn’t affect ink delivery, cleaning cycles, or waste handling directly. Good on you for confirming the reconnection with an Epson tech—that step ensures your control interface is back in working order.

Power Cleaning Without Waste Ink: What It Means

You've already:

• Replaced the maintenance box

• Manually flushed the printhead using a syringe

• Performed a Power Cleaning cycle

Yet the maintenance box remains empty, and printouts are blank—those two clues strongly suggest the waste ink line is clogged or the pump system has failed.

Under normal conditions, Power Cleaning should push a substantial amount of ink through the printhead into the capping station, which then routes it via the waste line to the maintenance box. If that system is obstructed:

• Ink won't flow.

• The pump won’t draw.

• No ink reaches the maintenance pad.

• The maintenance box chip may not register use, keeping the counter unchanged.

So your instinct is spot-on: don’t run a Power Ink Flush until the waste system is confirmed to be working. A flush under these conditions could cause ink to back up into the chassis and leak inside the printer.

Why the Maintenance Box Still Shows as Full

The Epson ET-3750 doesn’t measure actual ink volume inside the maintenance box—it relies on the chip embedded in the box. If the printer still reads it as full, here’s what might be happening:

1. Chip isn’t making proper contact: Try removing and reseating the maintenance box, or replacing it again to ensure a good electrical connection.

2. Firmware cache hasn’t reset: The printer may still be locked into a “full box” state and require a hard reset.

3. Waste ink pump isn’t cycling: A dead or clogged pump won’t register waste ink flow, and this can keep the counter from updating or triggering.

4. Third-party box compatibility: Some third-party boxes or chips may not be fully recognized by Epson firmware—try an OEM box if possible.

Confirming a Clogged Waste Ink Line

These signs indicate a blockage:

• No sound or vibration from the pump during Power Cleaning

• Maintenance box stays dry after multiple cleaning cycles

• No suction through the capping station or the sponge looks dry/cracked

Next Steps to Troubleshoot and Fix

1. Inspect the waste ink line
   If you're comfortable opening the back panel, locate the clear or translucent tubing that carries ink from the capping station to the maintenance area. If it appears discolored, stiff, or visibly blocked, it may be filled with dried ink and needs to be flushed.

2. Use a syringe on the waste tube
   Gently attach a syringe to the line and attempt to draw through it. Resistance or complete blockage means the waste system is compromised and will need either a cleaning or tubing replacement.

3. Manually test the waste pump
   If you can access the pump mechanism, try running it disconnected to see if it moves fluid. If the pump doesn’t engage or move ink, it may have failed mechanically or electrically.

4. Check the capping station sponge.
   If the sponge is dried or crusty, it won’t create a proper seal or suction on the printhead. Try flushing it with cleaning fluid or replacing the capping unit if needed.

Still Printing Blank Pages?

If ink still doesn’t flow after confirming waste functionality:

• Double-check the ink delivery system: Air bubbles or dried ink in the dampers or lines can stop flow.

• Ensure ink tank caps are open: Epson EcoTanks require the caps to be unsealed to equalize air pressure. If the tanks are sealed, the ink may not move.

• Purge airlocks: Use your syringe tool to draw ink from the printhead or damper assembly gently.

Addressing printer issues like this can be a complex and hands-on process. Unfortunately, we’re not able to offer remote diagnostics or support. However, we provide in-person evaluation and printer repair services at our diagnostic facility (https://bchtechnologies.com/printer-repair-service). Due to high demand, our repair queue is handled on a first come, first served basis and may require a waiting period. We support both complete printer repairs and component-specific services, with clear instructions for drop-off. That said, we understand our pricing might not fit every budget. We always encourage customers to seek DIY support by searching for guides on YouTube or directly through our YouTube homepage (https://youtube.com/@bchtechnologies). Use the search icon next to the “About” tab to locate videos specific to your issue. With hundreds of uploads over the years, that’s the fastest way to find what you need.

Thank you again for contacting us and for supporting BCH Technologies. We look forward to hearing how your repair progresses. Once you're back up and running, we’d love to be your trusted ink supplier!