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Quick answer
Stop the cycle and identify whether the noise is a scrape, rattle, hum, pop, or spark. Clean food buildup, check the glass tray and support ring, and remove cookware with metallic decoration. If the sound continues with smoke, arcing, a burnt smell, or a damaged rotating part, stop using the microwave and arrange service.
Before you begin
Safety first
- Never run an empty microwave and never open its cabinet to inspect the magnetron or other high-voltage parts.
Work through in order
Diagnostic checks
Use only checks that match the exact appliance or system and its official guide.
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Check 1
Stop the cycle, let the cavity cool, and describe the noise by timing and character: only while the tray rotates, only with a particular dish, or present whenever the oven energizes.
Expected result: The noise follows rotation or cookware, or it is a pop/crackle with a flash or smoke.
Next step: For arcing, smoke, or a burnt odor, leave the unit off and request service. Otherwise inspect the cavity and tray.
Why this matters
Why: Rotation and cookware clues support an accessible check; popping, flashing, or smoke is an arcing or fault warning.
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Check 2
Remove the glass tray and support ring, clean the cavity floor and the contact surfaces, then reinstall the ring and tray so they sit level in the model's guides.
Expected result: The ring or tray was dirty, tilted, cracked, or rubbing, or it is correctly seated but the noise remains.
Next step: Replace only visibly damaged accessible tray accessories using model-specific fitment, and arrange service if the sound remains.
Why this matters
Why: LG says food buildup and incorrect tray/support installation can cause noise or unstable rotation; persistent noise after correction needs diagnosis.
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Check 3
Inspect the dish used during the noise event and remove gold, silver, metallic-patterned, or otherwise unapproved cookware before any further test.
Expected result: The noise occurs only with decorated cookware, or it occurs with microwave-safe cookware as well.
Next step: Do not operate with metallic decoration. Stop and arrange service for recurring sparks or noise with suitable cookware.
Why this matters
Why: LG warns that metallic decoration can cause sparks; recurrence with suitable cookware points back to the oven or rotating system.
Use your observations
Decision map
Find the observation that best matches what you see, then follow the next safe action.
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PATH 01Next step
What you see
The sound is a light rattle or scrape tied to tray rotation and stops after cleaning/reseating
Do this next
Keep the accessories level and clean; monitor normal operation.
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PATH 02Next step
What you see
The sound appears only with a dish that has metallic decoration
Do this next
Remove that cookware and do not use it in the microwave.
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PATH 03Next step
What you see
Popping, flashing, smoke, or a strong burnt odor continues after suitable cookware and a clean, level tray
Do this next
Stop immediately and arrange qualified microwave service; do not open the cabinet.
Helpful context
Understand the symptom
A turntable rattle is not the same as arcing
LG lists food buildup, improper cookware, and an incorrectly installed tray or support as accessible causes of abnormal noise. The sound's timing and location determine whether cleaning is reasonable or immediate service is safer.
Only after diagnosis
Potential parts
- glass turntable tray or support ring
Consider an accessory only if the existing tray or ring is visibly cracked, warped, or no longer seats correctly after cleaning.
Confirm the exact LG model and dimensions before ordering; do not assume a generic accessory fits.
When checks do not resolve it
Need a professional?
Request qualified diagnosis for persistent noise or any sparking event.
Safety scope: Never run an empty microwave and never open its cabinet to inspect the magnetron or other high-voltage parts.
Common questions
FAQ
Why does the tray rattle after cleaning?
Check that the support ring and glass tray are level and seated in the model's guides. A cracked or warped accessory should be replaced with an exact-model part; persistent noise needs service.
Is a popping sound safe to ignore?
No. If it comes with a flash, smoke, or burnt smell, stop immediately. Remove metallic cookware only when the unit is stopped and arrange service if the symptom repeats.
Read the exact guide
Official sources
- LG Microwave - Things to CheckLG USA Support · LG microwave noise, food buildup, cookware, and tray installation
- LG Microwave Owner's ManualLG Electronics · LG microwave cookware and empty-operation safety
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