HP Officejet Pro 8600 Won’t Turn On? Diagnosing Power Button and Motherboard Failures

Customer Question:

I’m using an HP Officejet Pro 8600 Premium. The power button had been acting strangely, so I’ve been unplugging the printer to turn it off. Now, it won’t turn on at all. I’ve already checked the power supply, and it’s delivering 32V. Could this be caused by a short circuit in the printhead that’s affecting the motherboard or power circuitry? Do you have experience with this kind of issue?

Response:

Diagnosing Power Failures on the HP Officejet Pro 8600 Premium

You've already done a great job narrowing down the issue by confirming the power supply is delivering 32V. This tells us the external power adapter is likely functioning properly—the fault now lies somewhere internally, likely involving one or more of the following:

1. Faulty Power Button (Most Likely Starting Point)

If the power button had been acting up before the unit became completely unresponsive, that’s often the first place to investigate. Repeatedly pulling the plug can stress internal circuits over time, especially if the button wasn’t effectively completing the power cycle. Either the button mechanism itself or the related power control IC on the mainboard may be failing.

2. Short Circuit in Printhead or Carriage Assembly

Yes, your intuition is correct: a shortened printhead or carriage ribbon cable can cause damage to the logic board or trigger protective shutdown behavior. HP printers, like the 8600, often include overcurrent protection mechanisms. If a component downstream (such as the printhead or a damaged flex cable) draws too much current or shorts internally, the board may enter a “locked” or “protected” state and refuse to power up, preventing further damage.

3. Isolation Test: Disconnect the Printhead

If you're comfortable with disassembly:

• Unplug the printer and wait at least one full minute to allow capacitors to discharge.

• Carefully open the top cover and locate the printhead cable (often a wide flat flex cable going into the print carriage).

• Disconnect the printhead ribbon cable from the mainboard.

• Plug the printer back in and try powering it on.

Suppose the printer powers up after the printhead is disconnected. In that case, that’s a strong indicator the fault lies beyond the printhead connector—either in the printhead itself, the carriage board, or associated cabling.

Be extremely cautious when handling internal connectors. Always unplug the printer completely before disconnecting or reconnecting components.

4. If the Printer Still Doesn’t Power On

In this case, the issue is likely on the mainboard itself. This could be:

• A fried voltage regulator.

• A damaged power MOSFET.

• A failed system-on-chip (SOC) controller due to overvoltage or improper shutdown behavior.

In some cases, the logic board enters a non-recoverable fault state, and replacement is the only practical solution. Suppose you’re handy with electronics and have a multimeter. In that case, you can test voltage points on the board, but this is usually more feasible with a schematic and some experience with microelectronics.

If you’d like a detailed step-by-step diagnostic sequence, feel free to email us at support@bchtechnologies.com. We may also have replacement parts or reference materials for the 8600 series logic board, depending on the issue you're experiencing.

A Note on Repair Support and Services

Printer repairs like this often require direct physical inspection, and unfortunately, we’re unable to provide remote diagnosis or real-time repair guidance. However, we do offer an in-person printer diagnostic service (https://bchtechnologies.com/printer-repair-service) through our local facility. Please note that due to high demand, turnaround time is typically a few weeks, and we operate on a first-come, first-served basis. We offer repair services for both complete units and individual components, along with detailed instructions on how to proceed.

That said, we acknowledge that our services may not be suitable for every budget. We highly recommend using online resources, starting with our YouTube channel (https://youtube.com/@bchtechnologies). Use the search function (click the magnifying glass icon next to "About" on our channel page) to find videos about power issues, motherboard repair, or disassembling the HP Officejet 8600. YouTube may also suggest relevant content from other creators that can help you continue the repair yourself.

Thanks again for your thoughtful question and for trusting BCH Technologies as a resource in your printer repair journey. We’re always here to help you explore and understand your options. Best of luck with your HP Officejet Pro 8600 Premium, and let us know if you need further assistance.