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 voltage between the red (20) and brown (21) wires at the right hand plug on the PCB.
0V DC should be measured.
Note:
Test must be done within 20 seconds of turning the power on. Repeat test as necessary to ensure correct result.