The Relay Board is an OEM part for GE microwaves. It controls the passage of proper voltage levels for various microwave components during operation. Installed internally, this board transmits power signals to run the magnetron, fan, and lighting systems as directed by the selected cooking settings. Precise switching of voltages is required for consistent and balanced microwave radiation.  Symptoms of a faulty relay board include:   Intermittent or unpredictable power level adjustments Magnetron fails to turn on or fluctuates excessively Light not illuminating properly   Fan speed irregularities Microwaves not properly heating foods Causes can be damage from liquid intrusion, heavy usage over time stressing the relays, or component failures within the board itself. Replacing with this genuine OEM GE part restores optimized power routing to maintain consistent microwave functions. Compatible models also include some Hotpoint, RCA, and select Kenmore products.WB27X32849 (AP6890583) replaces WB27X10859, 4931328, PS12725850.