Question: I need help diagnosing an unstable, unpredictable issue with my DTF printer (Achi 1390 on the Epson R1390 platform). The printer randomly shows error 2H (CR Load Position Lock) and error 50H. Sometimes it works normally after power cycling and can print multiple jobs, then suddenly the error returns-often after finishing a print or on the next startup. After cleaning, it may work correctly, but without any change, the error comes back. The carriage moves freely and there's no obvious mechanical blockage. I have cleaned the encoder strip, cleaned the CR/home sensor area, inspected the carriage rail and drive belt, power reset, tested after long idle time and continuous operation, and visually inspected cables/connectors. A seller suggested sensor failure, blown fuse on mainboard, ribbon cable/wiring issues, but no definitive diagnosis. Do these symptoms point more to a CR/home sensor problem or to a mainboard/fuse issue? Have you seen cases where cleaning helps but the error returns randomly? Which parts are worth replacing first? Can standby/ready mode make it worse?

Answer:

You're seeing two key error codes:

• 2H - "CR Load Position Lock" (carriage position cannot be confirmed/locked at the expected location)

• 50H - carriage/home-position related fault (commonly tied to CR sensor feedback, encoder feedback, carriage movement timing, or the home position detect process)

On the Epson R1390 platform, these two errors appearing randomly almost always mean the printer is losing reliable position feedback intermittently. That feedback is mainly provided by:

1. Encoder strip + encoder sensor (timing/position feedback)

2. CR/home sensor (home position detection)

3. Carriage/head cables (ribbon cables) and connector seating

4. Carriage board / mainboard driver circuitry

5. Less commonly: power supply instability or a failing motor driver under load

Because your printer can run perfectly and then fail again, the problem is more consistent with an intermittent electrical/signal issue than a hard mechanical obstruction.

1) Do these symptoms point more to a sensor issue or a mainboard/fuse issue?

When it's more likely a sensor/feedback problem

Your description strongly matches intermittent signal loss from:

• Encoder sensor (or contamination returning quickly)

• Home/CR sensor (intermittent read)

• Ribbon cable / wiring (micro-fracture, oxidized contact, partially seated connector)

• Carriage board issues (if your setup uses one)

Why? Because if it were a true mechanical jam, you'd usually see:

• consistent grinding, binding, or repeatable failure at the same carriage location

• visible stalling every time you attempt initialization
  But you're seeing random behavior that temporarily improves after cleaning and power cycling.

Also, when cleaning "helps," it often means you briefly improved:

• optical clarity (encoder strip read)

• sensor window cleanliness (home/CR)

• contact seating (moving cables around during cleaning can temporarily improve a marginal connection)

When it's more likely a mainboard/fuse problem

A true blown fuse or hard power fault on the mainboard is typically:

• consistent (printer won't initialize, won't drive motor, won't power certain subsystems)

• not "sometimes it works perfectly for multiple jobs"

However, a mainboard can still be involved in intermittent cases if:

• a driver transistor/MOSFET is failing under heat

• solder joints are cracked and open when warm

• voltage regulation becomes unstable after a few jobs (thermal drift)

So the honest answer is:

• Most commonly: sensor/encoder/cable intermittency

• Less commonly (but possible): mainboard driver/regulator intermittency

2) Have people seen "works after cleaning, then randomly returns"?

Yes-this pattern is very common on DTF conversions built on Epson platforms.

Reasons cleaning appears to help:

• DTF ink mist and adhesive vapor can redeposit quickly on sensor windows and encoder components.

• The encoder strip can look "clean" but still have a thin film that scatters light.

• Cleaning often requires moving the carriage and harness, which can temporarily "reset" a marginal ribbon connection.

In DTF environments, contamination returns faster than in normal inkjet use, which is why intermittent carriage errors are more common on DTF machines than stock photo printers.

3) What parts are worth replacing first (best "preventive" order)?

Since you're trying to minimize random downtime, the most cost-effective approach is usually to replace high-probability intermittent items first-the ones that commonly fail in DTF use and can cause both 2H and 50H.

Highest priority replacements (most common root cause)

1. CR/encoder sensor (carriage encoder sensor)

   • If the sensor intermittently fails to read the strip, the carriage can't confirm position, triggering CR lock errors like 2H and related faults like 50H.

2. CR/home sensor (home position sensor / PF or CR home depending on variant)

   • If home isn't detected reliably at startup, initialization fails and errors appear random.

3. Carriage ribbon cable(s) / head data cables

   • These cables flex constantly. A cable can look fine but have internal fractures that open and close as the carriage moves.

   • Reseating is not enough if the copper traces are fatigued.

Next tier (situational but common in DTF)

1. Carriage board (if your Achi 1390 has one on the carriage)

   • Some conversions add intermediate boards; these can develop cracked solder joints or corrosion.

2. Power supply / DC harness checks

   • An unstable supply rail can cause sensors and logic to misread, especially during motor load.

Last tier (when you've ruled out sensors/cables)

1. Mainboard

   • If you've replaced sensors and cables and the problem persists, the mainboard becomes more likely-especially if errors correlate with heat, long run time, or specific motion phases.

This order is based on probability and on the fact that intermittent failures are most commonly caused by moving parts (cables) and optical sensors exposed to DTF contamination.

4) Can standby/ready mode make it worse?

It can-depending on how your printer behaves in standby.

Here's why standby might worsen intermittent errors:

• Heat soak: Electronics that are marginal can fail more often when warm (mainboard drivers, sensor circuits, cracked solder joints).

• DTF vapor exposure: Leaving the printer "ready" in a DTF environment can expose the carriage area to airborne mist longer, allowing more residue to settle on sensors/encoder.

• Micro-movements or periodic maintenance cycles: Some setups perform minor activity or keep certain circuits energized, which can exacerbate thermal drift.

That said, standby is not usually the root cause-it typically just makes an underlying marginal component fail more often.

5) What your symptom set suggests most strongly

Based on everything you wrote-especially:

• random 2H (CR Load Position Lock) and 50H

• temporary improvement after cleaning

• carriage moves freely

• no consistent mechanical blockage

• can print multiple jobs before failing again

...the most likely culprits are:

• encoder sensor/strip readability issues (including fast re-contamination)

• home sensor intermittency

• ribbon cable/harness intermittency
  with the mainboard as a secondary possibility if the issue is heat-related or if driver circuitry is failing under load.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems, and intermittent DTF faults are especially difficult to confirm remotely because they often require part-swapping, heat testing, and physical inspection under real operating conditions. For that reason, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We offer an in-person evaluation and repair service via our local diagnostic facility: printer repair service (https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first-come, first-served basis, so it might take a few weeks before we can get your printer scheduled for drop-off. Our services are structured to repair either an entire printer or specific parts, with clear instructions on how to proceed. However, we acknowledge our rates aren't the most economical. Thus, we highly recommend that you resort to self-help through online research. You can start by checking out YouTube or visiting our YouTube channel's homepage, BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Look for specific videos using the search icon next to "About" on the right-hand side of the menu bar. I receive dozens of queries every day asking about videos for specific topics. Having created videos over the past nine years, it's challenging to remember every single one. Therefore, using YouTube's search function would be most efficient. Plus, YouTube might suggest relevant videos from other channels that could assist you.

Thank you again for reaching out and for explaining the symptoms so clearly. I know it's frustrating when a printer behaves perfectly and then fails without warning-especially when production depends on it. I truly appreciate your patience and your support of BCH Technologies, and I hope the guidance above helps you prioritize the most likely parts first and reduce that random downtime.