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 the terminal in line with the white wire at connector J2 on the PCB and a suitable earth.
Expect approximately 18 VDC.