InkSonic L1800 Flashing Red Ink Light, Carriage Slamming Side to Side, and Possible Encoder Fault

Question:
I have an InkSonic L1800 DTF printer with a flashing red ink droplet light. I believe it may be an encoder fault. The carriage runs hard to the right side near the ink tank area, then moves back to the left only about 10 mm. How can I reset the encoder or return it to the correct position?

Answer:

A flashing red ink droplet light on an L1800-style printer does not automatically mean an encoder failure. That is a very common assumption because encoder-related problems often cause violent carriage movement, carriage mispositioning, or the printhead slamming to one side. However, the same light can also appear for several different fault conditions, so the first step is to identify the actual stored error code rather than guessing based only on the light.

In your case, the symptom you described is important: the carriage runs toward the right side near the ink tank area, then returns only a short distance. That kind of movement often suggests the printer is failing its position read, which can indeed involve the CR encoder system. On Epson-based L1800 platforms, this may be related to the encoder strip, encoder sensor, timing/position reading, or even a mechanical obstruction that prevents normal initialization. But it can also be triggered by related faults such as a CR motor issue, APG-related problem, home-position detection issue, or a board/cable problem.

The best way to confirm the problem is to use the Epson Adjustment Program. This is a service utility used to read the printer's internal fault history. Here is the process:

1. Open the Adjustment Program.

2. Select the USB port that shows your printer's name.

3. Choose Particular Adjustment Mode.

4. Scroll to Printer Information Check.

5. Click Check.

6. The latest stored fault will appear at the top as Error Number 1.

That error code is much more reliable than trying to diagnose the machine by the red light alone. Once you have that code, you can interpret it much more accurately. For example, some printers may report an APG sensor error, a CR encoder error, a carriage overload, or another stored fault that points you in the right direction.

If you want a quick walkthrough of how to access that information, you can watch our short video here: Adjustment Program walkthrough [https://youtube.com/shorts/FPZzpyYuZLE].

Now, regarding your question about how to "reset the encoder" or put it back in position: in most cases, the encoder itself is not something you reset electronically. The encoder system on this printer normally consists of:

• the clear encoder strip running behind the carriage path,

• the encoder sensor mounted on the carriage,

• and the printer logic that reads the markings on that strip.

If the printer cannot read the strip correctly, it loses track of carriage position. That can cause the carriage to shoot to one side, hesitate, move only a short distance back, or repeatedly fail during startup.

Here are the most common things to check:

1. Dirty encoder strip
If the strip has ink mist, grease, dust, or cleaning fluid residue on it, the sensor may misread it. This is one of the most common causes.

• Power off the printer.

• Locate the transparent encoder strip behind the carriage.

• Clean it gently using a lint-free cloth or foam swab slightly dampened with water or isopropyl alcohol.

• Do not pull hard on the strip. It is easy to damage or dislodge.

2. Encoder strip out of position
If the strip is not sitting correctly in the sensor slot, the printer may not read position data at all.

• Check whether the strip is twisted, loose, detached on one end, or sitting outside the encoder sensor fork on the carriage.

• If it slipped out, it must be rethreaded carefully through the sensor.

3. Damaged encoder strip
A scratched, ink-stained, stretched, or torn strip can cause false readings.

• Inspect it under good light.

• If the markings are damaged or the strip is physically deformed, replacement may be necessary.

4. Dirty or failed encoder sensor
Even if the strip is clean, the sensor on the carriage may be dirty or failing.

• If the printer has had heavy ink contamination, overspray may have entered the sensor area.

• Cleaning around the sensor may help, but sometimes the sensor itself is defective.

5. Carriage path obstruction
A foreign object, dried ink buildup, warped tubing, or snagging cable can interfere with carriage motion and create symptoms that look like encoder failure.

• Check the full carriage path from left to right.

• Look for tubing catching, loose parts, scraps of film, bits of paper, or hardened ink around the capping station and parking area.

6. CR cable or mainboard issue
If the carriage sensor cable is loose, damaged, or improperly seated, the signal may not reach the board correctly. On converted DTF units, cable routing can sometimes be less stable than on factory stock printers.

• Inspect flat cables and sensor connections if you are comfortable doing so.

• Reseat only carefully, because flat flex cables are fragile.

7. Home-position or related sensor issue
Sometimes the problem is not the encoder strip itself, but another sensor involved in initialization. If the printer does not detect its home or expected startup position, it may behave erratically and still show a general error state.

As for manually putting the carriage "in position," the printer normally establishes that position on its own during startup. There is no normal user reset procedure where you simply park it and the problem is solved. If the printer cannot read the encoder or complete initialization, manually moving the carriage will only be temporary unless the underlying cause is fixed.

If you want to try a basic recovery approach, here is a safe sequence:

• Turn the printer off and unplug it.

• Move the carriage gently by hand only if it is unlocked and moves freely. Do not force it.

• Inspect the encoder strip and carriage path.

• Clean the strip carefully.

• Check for anything blocking the carriage near the right side parking area.

• Restart the printer and observe whether the movement changes.

• Then use the Adjustment Program to read the actual stored error code.

Please pay attention to the specific error number reported by the software. That number is the key. If the machine reports a CR encoder error, then focus on the strip, sensor, alignment, and cable path. If it reports an APG sensor error, then the fix may be in a different area entirely. If it reports a carriage overload or mechanical lock type of error, then something may be physically binding the carriage or drive system.

Printer issues like this are often complex because they are hands-on and mechanical in nature. Because of that, we are not able to provide remote repair troubleshooting or step-by-step support for printer repair work. We do offer an in-person diagnostic and repair service through our local facility: printer repair service [https://bchtechnologies.com/printer-repair-service]. Due to high demand, repairs are handled on a first-come, first-served basis, and it may take a few weeks before we are able to accept a printer for drop-off. We can service either a complete printer or specific assemblies, with instructions provided for each option. That said, we also understand that our service may not be the lowest-cost path, so we strongly encourage self-help research when possible. A good place to start is YouTube or our channel homepage at BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies]. Use the search icon next to "About" on the right side of the menu bar to look for your exact topic. I receive many questions every day asking whether we have a video on a specific issue, and after creating videos over so many years, YouTube search is usually the fastest and most efficient way to find the right one. It may also suggest useful videos from other channels that can help.

Thank you again for reaching out to us and for supporting BCH Technologies. We sincerely appreciate your engagement, and we hope this gives you a clearer direction for diagnosing the fault.