my oven makes a loud buzzing or humming sound when it's on, not the fan, but like an electrical noise.

Diagnosis

The loud buzzing or electrical humming you are hearing in your Samsung NE63A6511SS is caused by "relay chatter" occurring on the main Oven Control Board (PCB). Inside the control board, there are electromagnetic switches called relays that open and close to send high-voltage power to the bake and broil elements. When the oven is maintaining a specific temperature, these relays cycle on and off rapidly. If the internal spring mechanism of the relay weakens or if the contact points become pitted and carbonized, the relay cannot "seat" firmly, causing it to vibrate rapidly against the contact—creating that distinct electrical buzzing sound. This is distinct from the cooling fan or the convection fan, which produce a mechanical whirring. Electrical buzzing is usually most audible during the "maintenance" phase of heating, where the oven is pulsing power to keep the temperature steady. You can confirm this is a relay issue by noticing that the sound fluctuates in sync with the heating element cycling. If the noise persists even when the oven is set to a low temperature, the relay is likely failing to maintain a clean connection, which can eventually lead to a complete failure where the oven won't heat at all or won't stop heating.

How to Fix It

Because the relays are surface-mounted and soldered directly to the main PCB, you cannot replace the individual switch. The only permanent resolution is to replace the entire Main Control Board assembly.

1. Disconnect Power: Completely shut off the power to the range at the circuit breaker. Do not rely on the oven being "off" at the display; this is a high-voltage repair.
2. Access the Control Panel: Remove the screws located at the rear of the console (the back-splash area). Carefully pull the console forward or lift it up depending on your specific installation to expose the wiring.
3. Disconnect Wiring: Take a clear photo of the wiring harness. Unplug the multi-pin connectors from the main PCB. Be careful not to bend the pins on the board.
4. Remove the Board: Unscrew the mounting brackets holding the PCB in place. Carefully slide the board out of its housing.
5. Install New Board: Align the new Samsung replacement PCB (ensure the part number matches your specific build date) into the housing and secure the mounting screws.
6. Reconnect and Test: Plug the wiring harnesses back into their original slots. Lower the console back into place and secure the rear screws. Restore power at the breaker and run a test bake at 350°F to ensure the buzzing has ceased.

If That Didn't Work

• Inspect the Heating Elements: If the noise persists, check the bake element for "hot spots" or physical warping. A failing element can occasionally create an electrical arc or vibration that resonates through the oven cavity, mimicking a relay buzz. Look for blistering or white spots on the element coil.
• Check for Loose Wiring: Inspect the terminal block at the back of the range where the main power cord enters. If a wire is loose or a screw is not tightened to specification, it can cause a "micro-arcing" sound that sounds like a buzz. Tighten all terminal screws with a screwdriver.
• Verify Voltage Stability: Use a multimeter to check the incoming voltage at the terminal block. If your home is experiencing a voltage drop (brownout) or unstable power, the relays may struggle to engage fully, causing them to chatter. You should see approximately 240V across the two hot legs.
• Test the Cooling Fan Motor: While you mentioned it's not the fan, a failing bearing in the cooling fan (which runs independently of the convection fan) can produce a high-pitched electrical whine that sounds like a buzz. Check if the noise changes when the oven reaches its peak temperature and the cooling fan kicks into high gear.

Heads Up

• Avoid "Quick Fixes": Do not attempt to spray contact cleaner or lubricants into the control board relays. This can cause a short circuit or a fire hazard due to the high amperage passing through these components.
• Static Discharge: When handling the new PCB, touch a grounded metal surface first. Static electricity can fry the microprocessors on the board before you even install it.
• Avoid Overloading: Ensure your range is on a dedicated 40-amp or 50-amp circuit. Sharing a circuit with other high-draw appliances can cause voltage fluctuations that accelerate relay wear.
• Check for Recalls: Before ordering a board, check your specific serial number for any Samsung service bulletins regarding control board revisions, as newer versions of the board often have improved relay tolerances.