Diagnosing Power Failure on a Procolored F13 (Epson L1800 Base): Causes, Symptoms, and Repair Advice

Issues can sometimes appear suddenly and escalate quickly when dealing with modified or converted printers like the Procolored F13, built on the Epson L1800 platform. A recent case involving a customer highlights a typical failure pattern: The printer powers on faintly at the rear switch but shows no activity on the front panel. The only signs of life are a slow, blinking green light and faint beeping from the motherboard.

This article will walk through the potential causes of this kind of failure, what it means when the motherboard enters protection mode, how printhead issues can trigger board-level damage, and whether it’s worth repairing or replacing affected components.

Symptoms of a Power Fault on the F13

In this particular case, the customer reported that the printer:

• Lit up only the rear power switch

• Showed no response from the front panel

• A faint, consistent beep was emitted from the internal board

• Displayed a slow blinking green light inside the printer

These are clear signs that the mainboard has entered a protection mode, a safety mechanism that prevents further elerical damage when the board detects a short circuit, failed transistor, or unstabite.

Prior Warning Signs: Faded and Smeared Prints

Before the total failure, the printer began producing smeared and faded prints. After attempting software-level fixes—including uninstalling and reinstalling the RIP software—the print quality temporarily improved. However, the problem returned within days, culminating in a complete power failure.

These symptoms suggest that the issue was not software-related but stemmed from a failing printhead or driver circuit. Such problems often begin with inconsistent firing, reduced ink output, or smearing. Left unresolved, they can lead to excessive current draw, especially during head cleaning or purge cycles, which overloads the motherboard components.

Transistor and Fuse Testing Results

Upon removing and inspecting the motherboard, the customer performed multimeter tests on the transistors:

• Transistors 2 and 4 measured 0.4 ohms and beeped on the continuity setting, indicating internal shorts.

• Transistors 1 and 3 measured 42.9 ohms without continuity, which could suggest open or degraded states.

This imbalance between the transistors strongly points to failed MOSFETs, which control high-voltage firing signals to the printhead. Once one or more of these transistors fail, the board may no longer regulate power properly, triggering protection mode.

What Causes This Kind of Failure?

Several factors could have contributed to this motherboard failure:

1. Overheating or Clogged Printhead
   A partially blocked printhead can generate excess resistance or current, leading to transistor stress and eventual shorting.

2. Voltage Spike During Cleaning Cycle
   The resulting surge can damage the switching circuits if a component fails mid-cycle during a head cleaning or purge.

3. Damaged or Aged FFC Ribbon Cables
   Even cables that look intact can have internal faults—like micro-cracks or arc marks—that short under load.

4. Unstable or Faulty Power Supply
   In rare cases, a power supply with voltage regulation issues can overdrive the board.

Why the Board Powers On With a Disconnected Cable

The user noted that disconnecting a small red/black wire on the right side of the motherboard allowed the board to power on. This cable is likely tied to the printhead ground line or a thermistor input. Unplugging it essentially interrupts the faulted circuit, letting the board start up but not fully initialize, meaning it can’t function or print correctly in that state.

Is Repair Worth Pursuing?

Yes, repairing the board can absolutely be worthwhile—especially if you’ve already taken the time to remove it and l, bel the cables, as this user removed it and labeled

At BCH Technologies, we offer a diagnostic and repair service where we can:

• Confirm the root cause of failure

• Replace damaged components such as transistors, fuses, or voltage regulators

• Test the board with known-good cables and printheads on our bench setup

• Help you avoid replacing the entire board when only a few parts have failed

To get started, visit our Printer Repair Service page (https://bchtechnologies.com/printer-repair-service).

Important Tips for Reinstallation

• Replace the Ribbon Cables: Even if they look fine, old FFC cables may have invisible damage that could short your new board or printhead.

• Avoid Direct Contact with Pins: Handle them carefully, and ground yourself to avoid static shock to the components.

• Check for Proper Grounding: Inconsistent or missing ground paths can cause performance issues or damage.

Final Note

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. So, we cannot provide remote troubleshooting, suggestions, or support for printer repairs. We offer an in-person evaluation and repair service via our local diagnostic facility (https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first come, first served basis. It may take a few weeks to get your printer dropped off. Our services are structured to repair a whole printer or specific parts, with clear instructions on how to proceed. However, we acknowledge that our rates aren't the most economical. Thus, we recommend that you resort to self-help via online research. You can start by checking out YouTube or visiting our YouTube channel's homepage (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.

Thanks again to our community for your continued engagement and for bringing thoughtful, detailed technical cases to our attention. Don't hesitate to reach out if you’re dealing with a similar issue or have a board you’d like evaluated.