Unit emits a high-pitched whine or electronic squeal during operation.

Safety first: Unplug before opening the housing. Noise alone is not always dangerous but can indicate stress on components.

• Step 1 – Confirm source: Run briefly to locate the noise area (then unplug). It usually comes from the PCB.
• Step 2 – Inspect components: Check inductors and transformers for loose cores or insufficient adhesive. Gently press with an insulated tool (unpowered) to see if they are loose.
• Step 3 – Secure components: Apply high-temperature-safe electronic-grade silicone or varnish to secure vibrating coils if you are qualified.
• Step 4 – Replace PCB: If noise is loud or accompanied by instability, replace the main control board.