lg neochef keeps beeping 3 times after it finishes cooking, how do i make it stop?

Diagnosis

The three-beep sequence occurring at the end of a cooking cycle on the LG NeoChef LMC0975ST is not a mechanical failure or an error code; it is the factory-default "End-of-Cycle" audible alert. This feature is designed to notify the user that the magnetron has ceased operation and the timer has reached zero, preventing food from sitting and losing temperature. The issue persists because the NeoChef series utilizes a tiered volume system rather than a simple on/off toggle. If the unit is beeping, the internal logic board is set to a volume level (typically Level 2 or 3) that triggers the piezo buzzer. To confirm this is the standard alert and not a "Food Reminder" beep (which occurs every 60 seconds after the initial finish), observe if the beeps stop immediately after the third chime or if they repeat every minute. If they repeat, the microwave is in Reminder Mode; if they occur only once at the end, it is the standard Cycle Alert.

How to Fix It

To silence the end-of-cycle beeps or reduce their volume on the LMC0975ST, you must access the sound configuration settings via the control panel. Follow these precise steps:

1. Ensure the microwave is in standby mode (not currently cooking and the door is closed).
2. Locate the Sound button on the touch panel. On this specific NeoChef model, the Sound button often shares a function or is positioned near the clock/timer settings.
3. Press and hold the Sound button for approximately 3 to 5 seconds. You will see the display change from the current time or "0:00" to a sound setting indicator.
4. Press the Sound button repeatedly to cycle through the available volume levels. The display will cycle through:
   • Snd 3: Maximum volume (Loudest beeps).
   • Snd 2: Medium volume (Standard factory setting).
   • Snd 1: Low volume (Quiet beeps).
   • Snd 0: Mute/Silent (Completely disables the end-of-cycle beeps).
5. Once the display reads Snd 0, release the button and wait 3 seconds. The unit will automatically save the setting and return to the main clock display.

If That Didn't Work

• Check for "Reminder" Mode: If the microwave continues to beep every minute after the initial three beeps, you have the Reminder function active. To stop this, open the microwave door immediately after the cycle ends. Opening the door clears the memory and kills the reminder loop.
• Perform a Hard Power Reset: If the Sound button is unresponsive or the display is frozen, unplug the LMC0975ST from the wall outlet for exactly 60 seconds. This drains the capacitors on the control board and resets the firmware to factory defaults, which may resolve a glitch preventing the "Snd 0" setting from saving.
• Test for Stuck Buttons: Inspect the touch panel for any residue or grease buildup around the Sound and Start buttons. Because the NeoChef uses a capacitive touch interface, a smudge of oil or a piece of debris can cause the board to register a "phantom press," which may override your sound settings or trigger unexpected beeps. Clean the panel with a damp, microfiber cloth and isopropyl alcohol.
• Verify Child Lock Status: If the control panel is completely unresponsive to the Sound button, check if the Child Lock is active (indicated by a small lock icon or "L" on the display). Press and hold the Stop/Cancel button for 3 seconds to deactivate the lock before attempting the sound fix.

Heads Up

• Volume Memory: Be aware that after a total power outage or if the unit is unplugged, the LMC0975ST may revert to the factory default volume (Snd 2). You will need to re-apply the "Snd 0" setting.
• Safety Warning: Never attempt to open the outer casing to manually disconnect the piezo buzzer. The high-voltage capacitor inside a microwave can hold a lethal charge even when the unit is unplugged.
• Panel Care: Avoid using abrasive scrubbers on the touch panel. Scratching the surface can lead to moisture ingress, which causes the control board to malfunction and trigger random beeping.