Clock randomly requires reset

The clock/date will randomly require a reset as if power had been lost. No other electrical devices in the house are having any difficulties. I have replaced the control board with no improvement. Have reset breaker numerous times. Issue can takes from minutes to many hours to occur. The clock must be set before using any other oven features other than the lights. First noticed when cooking that the clock had lost the setting and the oven stopped heating. Trying to find a wiring diagram to see if I have an issue with any wires going to the control board.