Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
Use insulation mat as necessary
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across connection 4 (brown lead) and connection 3
(blue lead) on connector marked CON 6 on the control PCB.
Expected voltage - mains voltage.