Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Gain access to PCB (use Insulation Mat as required)
Remove fan DC connector (4 wire) and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the DC voltage between pin 7 on connector X8 and a suitable earth.
Expect approximately 23 vdc
Note:
Voltage will not be present for the first 5 seconds after
power is reinstated.