The unit may have been plugged in during a low voltage condition, resulting in an over-voltage condition. For example, The SPL III is turned on when the 117 volt line is under a heavy load and a voltage measurement indicated less than 111 volts. The SPL III selects the 108 volt tap. Later, if the same line is under no load and measures 120 volts, the SPLIII indicates a "Line Problem".
1. Turn off the unit using the orange on/off circuit breaker.
2. Wait 20 seconds.
3. Turn on the unit using the orange on/off circuit breaker. This forces the SPLIII to select the 117 volt tap.