The short answer
When a Black+Decker microwave does this, a grinding sound from under the tray is the turntable drive, and it is usually dirt rather than wear. Cleaning the ring and the cavity floor is free and ends most of these; worn wheels are a cheap part.
What you actually see
- A rattle from the top of the case — Rattles from above the cavity are usually the cooling fan or a loose cover screw.
- The glass tray clatters as it turns — A clattering tray is nearly always seated wrongly on its coupling.
- A whine that rises through the cycle — A rising whine points at the cooling fan speeding up as the oven warms.
- A buzz that has become noticeably louder over months — Gradual change is wear; sudden change is something that moved.
Causes, ranked for this microwave
- Food debris under the roller ring — Leads the ranking — it is common, cheap and easily missed because the debris is hidden by the tray. Where this checks out clean, treat the next entry as the working theory rather than a possibility.
- Roller ring or drive coupling worn — Close behind — the plastic wheels flatten and the coupling teeth round off with age, and both make noise before they fail outright. A clean result here does not just remove one part; it removes everything that depends on it.
- Glass tray or roller ring seated wrongly — A step down — it is first because it explains most turntable noise and because reseating costs nothing at all. It is worth being sure about this one rather than half-sure, since everything after it assumes a verdict.
What to check, in order
- First — the cavity floor — Remove the tray and the ring and wash both, then wipe the cavity floor and the coupling clean and dry.
- Second — the ring wheels and the coupling — Spin each wheel with a fingertip. A wheel that will not turn is dragging the whole ring around instead of rolling.
Checks an owner can do safely
- Step 1. Clear the vents — Move the oven so every vent has clear air and nothing is stored against the case where air is drawn in.
Tools: noneAbout 10 min
- Step 2. Compare full power against low power — Run a short cycle at each. A buzz present only at full power is the high-voltage section doing its job.
Tools: mug, waterAbout 10 min
- Step 3. Clean the cavity floor and coupling — Wipe the floor and the recess the coupling sits in. Dried spill acts as grit and turns a silent drive into a grinding one.
Tools: cloth, warm soapy waterAbout 10 min
Before you open anything
Safety
Unplug the oven before anything else. A microwave stores enough energy in its high-voltage capacitor to be dangerous with the cord in your hand. Do not remove the cabinet, do not hold a door switch closed, and do not run the oven with the door damaged or ajar.
When this becomes a service call
Stop and call when the next thing to do meets any of these. Call, or replace the oven, when the noise is inside the case and continues with the tray and ring removed — that is behind a case that must not be opened.
Sources
General guidance- The Control of Hazardous Energy (Lockout/Tagout) — OSHA 1910.147 and manufacturer service manuals, fetched
Nearest pages
What this page does not cover
Read this as generalized information. It is accurate across the Black+Decker microwave range, which is exactly why it stops short of the detail a single family or model deserves. If a family-level or model-level page exists for your unit, that page supersedes this one on wiring, part numbers and error-code meanings; the links under Related pages are where those pages live.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
