HP Printer Power Supply (PSU) Errors – Causes, Diagnosis, and Step-by-Step Resolution

Power Supply Unit (PSU) errors occur on HP LaserJet and HP All-in-One printers when the printer fails to receive, regulate, or distribute stable electrical power.
These errors can cause no power, sudden shutdowns, continuous rebooting, or random error messages, severely impacting office productivity.

This Knowledge Base article explains HP printer PSU errors, their technical causes, and a structured approach to diagnose and resolve power-related failures safely.

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What Are HP Printer Power Supply / PSU Errors?

PSU errors indicate that the printer:

• Is not powering ON

• Powers ON briefly and shuts down

• Reboots repeatedly

• Displays power-related service errors

• Emits clicking, buzzing, or burning smells

Common Symptoms & Messages

• Printer completely dead (no lights)

• Power Error

• Turn off then on

• Continuous restart loop

• Control panel flickers or resets

• Printer shuts down during printing

PSU errors affect all printer functions, unlike software or network issues.

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Technical Explanation

The Power Supply Unit (PSU) converts AC mains voltage into multiple regulated DC voltages required by:

• Formatter board

• Engine controller

• Fuser assembly

• Scanner unit (MFP)

• Fans and motors

A PSU error occurs when:

• Input voltage is unstable

• Internal PSU components fail (capacitors, regulators)

• PSU protection circuitry trips

• Fuser draws excessive current

• Short circuit exists in connected modules

To prevent damage or fire risk, the printer enters a protective shutdown state.

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Common Use Cases Where PSU Errors Appear

• After power surge or lightning

• Unstable or fluctuating mains supply

• Using UPS or extension cords

• Printer moved between voltage regions

• Aging printer hardware

• Fuser or motor short-circuit

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Step-by-Step Troubleshooting & Resolution

Step 1: Verify External Power Source (Critical)

• Plug printer directly into wall socket

• Avoid:

  • UPS

  • Power strips

  • Extension boards

• Test with a known-good socket

• Confirm correct voltage (110V / 220–240V as per model)

✔ Eliminates external power issues

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Step 2: Perform Hard Power Reset

1. Turn OFF printer

2. Unplug power cable

3. Disconnect all data cables

4. Wait 20 minutes

5. Reconnect power cable only

6. Power ON printer

✔ Clears PSU protection latch conditions

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Step 3: Inspect Power Cable & Socket

• Check for:

  • Loose plugs

  • Burn marks

  • Damaged insulation

• Replace power cable if suspect

• Avoid shared sockets with heavy appliances

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Step 4: Isolate Internal Loads (Advanced)

For trained personnel only.

1. Power OFF and unplug

2. Disconnect:

   • Fuser unit

   • Scanner (MFP)

3. Power ON printer

Result	Meaning
Printer powers ON	Disconnected module faulty
Still dead	PSU failure

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Step 5: Check for Overheating or Burnt Smell

• Inspect vents and PSU area

• Look for:

  • Burnt smell

  • Excessive heat

  • Clicking sounds

⚠ Immediately power OFF if burning smell is present.

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Step 6: Replace PSU (Permanent Fix)

If printer remains dead or unstable:

• PSU board is faulty

• Replace with:

  • Model-specific HP PSU

  • Correct voltage rating

PSU repair at component level is not recommended in office environments.

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Common Issues & Fixes

Symptom	Root Cause	Fix
No power at all	PSU failure	Replace PSU
Reboots during warm-up	Fuser overload	Replace fuser
Powers ON then OFF	Voltage instability	Direct wall power
Clicking noise	PSU protection trip	Replace PSU
Power loss after surge	PSU damage	PSU replacement

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Security & Safety Considerations

• Never open PSU while connected to power

• PSU capacitors retain charge after unplugging

• Use ESD precautions

• Replace PSU only with certified parts

• Dispose failed PSU as electronic waste

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Best Practices

• Use voltage stabilizer in unstable power areas

• Avoid frequent power cycling

• Keep printer vents unobstructed

• Replace fuser at recommended intervals

• Schedule periodic electrical inspections

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Conclusion

HP printer power supply (PSU) errors are electrical hardware failures that affect all printer operations.
While external power checks and resets can resolve minor issues, PSU replacement is the definitive solution for persistent power problems.

Stable power infrastructure significantly extends printer lifespan.

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