Set Appliance State:

Mains Power Off
Set Multimeter to DC Volts Set meter to measure DC Volts
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the DC voltage between pin 4 (grey) on connector X20 and a suitable earth.
Expect approximately 24 Vdc.
Note:
Each pin on the PCB connector is numbered.