Why Did My Printer Power Off After Installing a New Motherboard and Power Supply?

Question:
I installed a new motherboard and power supply in my printer. At first, the printer powered up normally-I even updated the firmware and started a test print. But about a quarter of the way through the page, the printer shut down unexpectedly and now will not power back on. I confirmed that all connections are secure, tried different power cords, and even swapped out the power switch board, but the issue remains. Later, I removed the mainboard and noticed the power supply had a burnt smell. How can I test the power board to confirm if it's working or if it has blown a fuse? And if the power supply has failed, is there a way to test the new motherboard to make sure it hasn't also been damaged?

Answer:

When dealing with power-related issues like this, there are a few critical checks and steps to consider:

1. Power Supply Concerns

The burnt smell you detected from the power supply is a strong indicator that something has failed internally. Printer power supplies typically contain fuses and transistors that can blow when there's a short or overload. To test your unit:

• Disconnect the power supply from the mainboard.

• Use a multimeter to check continuity across the fuse and inspect the output voltage. If the fuse is blown or voltage output is not within expected ranges, the power supply is defective.

• You can follow along with this troubleshooting video we made for Epson models: Epson EPS-135 Power Supply Troubleshooting Guide (https://bchtechnologies.com/products/epson-eps-135-power-supply-for-l-1800-1430-1400-1390-r2000-no-return?_pos=12&_sid=9a01916b7&_ss=r).

2. Motherboard Safety Checks

When installing the motherboard and power supply, ensure neither touches the underlying metal chassis. If they do, the metal can cause shorts that lead to burnt components. In some cases, even if you replace the power supply, a damaged mainboard will prevent the printer from starting.

• If your printhead was the original cause of the mainboard failure (e.g., a shorted printhead burning out the board), installing a new board without addressing the root issue may cause repeated damage.

• Once the power supply has been confirmed good, reconnect it carefully to the mainboard and check for activity. If the printer still won't power on, the mainboard transistors may have been burnt during the event.

3. Repair Options

At BCH, we do repair mainboards when the transistors or other circuits have failed. This can sometimes be more cost-effective than replacing the entire board, but it depends on the severity of the damage.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. Because of this, we're unable to provide remote troubleshooting, suggestions, or direct repair support. We do, however, offer in-person evaluations and repair services through our local diagnostic facility (https://bchtechnologies.com/printer-repair-service). Please note that we operate on a first-come, first-served basis, so it may take a few weeks before your printer can be evaluated. Our service options include full-printer repairs or targeted repairs for specific parts, with detailed instructions on how to proceed. That said, we recognize that our rates aren't always the most economical. We therefore encourage self-help through research and tutorials, beginning with our YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon located next to "About" on the channel page to find videos related to your issue. Since we've produced content for nearly a decade, this method is much faster than asking us for a specific video, and it may also lead you to relevant resources from other creators.

Thank you again for reaching out. We appreciate your patience and your commitment to keeping your printer in working condition.