OK, my AC duplex’s output voltage is 226.2V.
Since I don’t have the service manual, I played around with the calibration settings and arrived at the following settings to trim both the setting and output to converge to, and match as closely as possible to 230.0V.
P20 (left)
Output Voltage Setting
-10, 230V
Input Voltage Reading
2, 226.3V
Output Voltage Reading
12, 230.7V
P20 (right)
Output Voltage Setting
-4, 230V
Input Voltage Reading
2, 226.3V
Output Voltage Reading
12, 230.3V