The Relay Board is an OEM part for GE microwave ovens. It functions as an electronic gatekeeper, controlling power levels and settings based on commands from the control panel.  Installed internally, this relay board routes appropriate voltages to the magnetron, fan, and other vital microwave systems during operation. Its components switch power on and off as the programmed cooking cycle directs. Causes of a faulty board can include liquid damage, overheating from heavy usage over time, or failures in relay components.  Symptoms of issues include:  Inability to select power levels or adjust time   Magnetron failing to cycle on or off correctly Fan or other internal parts not functioning as intended Microwave making unusual noises or failing to heat food Replacing with this genuine OEM GE part restores full functionality and precise cooking performance. Compatible models include some Hotpoint, RCA, and select Kenmore microwave products.WB27X33045 (AP6888702) replaces WB27X11021.