Set Appliance State:

Mains Power Off
Set Multimeter to DC Volts Set meter to measure DC Volts
Disconnect X1 from the PCB
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Test 1:
Measure for DC voltage between pin 66 on X1 to a suitable earth point.
Voltage should be approximately 4.6V DC.
Test 2:
Measure for DC voltage between pin 74 on X1 to a suitable earth point.
Voltage should be approximately 36V DC.
Test 3:
Measure for DC voltage between pin 75 on X1 to a suitable earth point.
Voltage should be approximately 4.6V DC.
Note.
Ensure a good connection is made and probe is only making contact with one pin else misdiagnosis will occur.