Epson 1390 Print Carriage Slamming Back and Forth: Encoder Problems, Mainboard Corruption, and EEPROM Reprogramming Options

Question:
My Epson 1390 printer has a problem where the print carriage is slamming back and forth. I originally thought the motherboard may need to be reprogrammed because the carriage movement is very violent. Can you help with this issue, and how can I get the Epson 1390 mainboard reprogrammed?

Answer:

For an Epson 1390 with the print carriage slamming, the first thing I usually suggest checking is the CR encoder system, not the motherboard. "CR" stands for carriage return, and this system tells the printer where the printhead carriage is located as it moves left and right.

The main parts to inspect are:

1. CR encoder scale, also called the clear timing strip or clear encoder belt
   This is the transparent strip that runs behind the carriage. It has very fine markings that the printer reads to track carriage position.

2. CR encoder sensor, located on the back of the carriage
   This sensor reads the markings on the encoder strip as the carriage moves.

3. Carriage belt, motor, and carriage path
   If the carriage is physically blocked, binding, or being pulled unevenly, the printer may lose position and crash.

When the CR encoder strip is dirty, scratched, knocked out of position, installed through the sensor incorrectly, or contaminated with ink mist, the printer can lose track of where the carriage is. The printer then keeps driving the carriage motor because it does not receive proper position feedback. That can cause a hard slam to one side.

However, there is an important difference. A bad or dirty encoder strip commonly causes the carriage to slam once, usually during startup or initialization. If the carriage is repeatedly slamming back and forth, then your suspicion about the mainboard becomes more reasonable. It does not automatically prove the mainboard is bad, but it does move the mainboard higher on the suspect list.

Before assuming the Epson 1390 motherboard needs reprogramming, I would check these items carefully:

• Make sure the clear CR encoder strip is seated correctly and runs through the encoder sensor slot.

• Clean the encoder strip gently with water or a mild cleaner that will not erase or damage the markings.

• Check that the strip is not twisted, stretched, scratched, or detached from either end.

• Inspect the CR encoder sensor on the back of the carriage for ink, dust, or physical damage.

• Confirm that the carriage can move smoothly by hand when the printer is powered off.

• Check for foreign objects, dried ink buildup, broken plastic, a jammed capping station, or anything blocking the carriage path.

• Inspect the carriage belt tension and motor gear engagement.

• Look for liquid damage, corrosion, burnt components, or damaged connectors on the mainboard.

If all of those areas look correct and the carriage still slams back and forth, then the problem could be related to the mainboard, corrupted memory, or a damaged control circuit.

For the Epson 1390, reprogramming the motherboard is not as simple as using a normal printer utility. There are a few different "levels" of reprogramming people may be referring to.

The first level is using software such as the Epson Adjustment Program or WICReset. These tools can sometimes reset counters, restore certain settings, or reload data that the printer uses during operation. If the issue is caused by corrupted service data or a bad setting stored in memory, this may help. This is the least invasive step and should be tried before removing chips from the board.

However, if the corruption is at the chip level, then software may not be enough. In that case, the memory chip itself may need to be read, backed up, erased, or written directly. That is where EEPROM programming comes in.

The Epson 1390 uses a non-standard external EEPROM-style memory arrangement compared with many common repair examples online. Because of that, public references are very limited. I do not know of a simple off-the-shelf programmer or public tool that reliably handles this board in the way people usually expect. For that reason, if someone wants to attack the problem directly at the EEPROM level, they may need to build or configure their own programmer.

That sounds intimidating, but the basic job of an EEPROM programmer is not complicated in concept. The programmer needs to:

• Power the chip correctly.

• Communicate with the chip through the correct pins.

• Read the existing data.

• Save a backup.

• Write new data if needed.

• Read the chip again.

• Verify that the written data matches the file.

A basic EEPROM programming setup usually needs these parts:

A controller
This can be an Arduino, Raspberry Pi, USB programmer module, CH341A-style board, or another microcontroller/programmer setup that can communicate with the chip.

Correct voltage supply
The chip may use 3.3V or 5V, depending on the exact chip. Do not guess. Applying the wrong voltage can destroy the chip or the mainboard.

Ground connection
The programmer ground and the chip ground must be connected together. Without a shared ground, communication will be unstable or impossible.

Communication lines
The programmer needs to connect to the chip's data and clock/control lines according to the chip's protocol. Some chips use a simple clock-and-data interface, while others use SPI or another serial format. The exact chip marking matters.

Optional write-protect control
Some chips have a write-protect pin. If that pin is held in the wrong state, the chip may read correctly but refuse to write.

Chip clip or SOP adapter
A clip may allow in-circuit reading, but it is not always reliable. The printer mainboard can interfere with the signals. Removing the chip and placing it in a proper SOP adapter is usually more stable, although it requires soldering skill.

The simplest learning setup is to remove the chip from the mainboard and place it in a SOP adapter connected to the programmer. In-circuit clips are convenient, but they often produce unstable reads because other components on the board remain connected to the same lines.

The general wiring idea is:

• Programmer VCC to chip VCC

• Programmer GND to chip GND

• Programmer CLK or clock line to chip clock pin

• Programmer DATA or data line to chip data pin

• Write-protect/control pin to the correct high or low state for writing

Before applying power, identify pin 1 on the chip. SOP chips usually have a notch, dot, bevel, or printed mark. Once pin 1 is known, count the pins around the package correctly. A reversed connection can destroy the chip.

The programming process should start with reading, not writing. This is extremely important. The first goal is to get a clean backup.

A safe reading process would be:

1. Initialize the programmer.

2. Send a test/read command.

3. Read the full chip into a file.

4. Read the chip again into a second file.

5. Compare both files.

6. If they match exactly, save the backup permanently.

7. Do not write anything until the backup is confirmed.

If the two reads do not match, do not continue. Mismatched reads usually mean one of the following:

• Bad clip contact

• Wrong voltage

• Incorrect chip selection

• Loose ground

• Board interference

• Wrong pinout

• Dirty chip legs

• Incorrect programmer settings

• A chip that must be removed from the board before reading reliably

A simple reading workflow would be:

• Open programmer connection.

• Set chip address to 0.

• Read one block of data.

• Save that block to a backup file.

• Move to the next block.

• Continue until the full chip is read.

• Read the chip again.

• Compare the first backup with the second backup.

• If both backups match, then the read is trustworthy.

Only after that should writing even be considered.

A writing workflow would be:

• Open the firmware or EEPROM data file.

• Set chip address to 0.

• Enable writing.

• Write one small block.

• Wait for the chip to finish writing.

• Move to the next block.

• Continue until all data has been written.

• Read the chip again.

• Compare the final read with the file that was written.

That final verification step is critical. A programmer saying "write complete" is not enough. You want the programmer to read the chip back and prove that the contents match the file.

For the Epson 1390 mainboard, I would treat EEPROM programming as a backup and recovery tool first, not as a blind firmware-editing project. Do not assume the chip contains only generic firmware. It may contain board-specific information, calibration values, counters, regional data, model data, or other unique information. If you erase it without a good backup, you may lose data that cannot easily be recreated.

My safe rule is:

• If you cannot read it twice and get the same file, do not write it.

• If you do not know the chip voltage, do not power it.

• If you do not have the original backup, do not erase it.

• If you are not sure of the pinout, do not connect the programmer.

• If the printer has a mechanical or encoder problem, reprogramming the board will not fix it.

Also, if the carriage is slamming because of a bad CR encoder sensor, dirty encoder strip, broken carriage cable, failing motor driver, or physical obstruction, reprogramming the motherboard will not solve the root cause. The printer may still slam after the board is rewritten. That is why it is important to rule out the encoder and carriage movement system first.

In short, I would approach the repair in this order:

1. Inspect and clean the CR encoder strip.

2. Inspect the CR encoder sensor on the carriage.

3. Check the carriage path, belt, motor, and capping station for physical problems.

4. Check all carriage and sensor cables.

5. Try software-level recovery such as an Epson Adjustment Program or WICReset-type utility.

6. Inspect the mainboard for corrosion, burnt components, or liquid damage.

7. Only then consider EEPROM-level backup and reprogramming.

8. If programming is attempted, read and verify the original chip contents before writing anything.

Addressing printer issues can be a complicated affair because many of these problems require hands-on inspection. For that reason, we are not able to provide remote troubleshooting, step-by-step repair support, or remote diagnosis for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility, BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]. Because demand is high, service is handled on a first-come, first-served basis, and it may take a few weeks before we can accept your printer for drop-off. Our repair service can be structured around either the whole printer or specific parts, with instructions provided on how to proceed. However, we understand that our repair rates may not be the most economical option for every situation. For that reason, we strongly recommend using self-help resources and online research when possible. A good starting point is YouTube, including our channel homepage, BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Once there, use the search icon next to "About" on the right-hand side of the menu bar to search for your specific topic. I receive dozens of questions every day asking where to find videos on specific repairs. Since we have made videos for more than nine years, it is difficult to remember every single one, so YouTube's search function is usually the fastest way to locate the most relevant video. YouTube may also recommend helpful videos from other channels.

Thanks again for contacting us and for supporting BCH Technologies. I hope this gives you a safer path for diagnosing the Epson 1390 carriage-slamming issue before attempting any mainboard reprogramming.