Set Appliance State:
Set Multimeter to DC Volts 
Isolate Mains Power to appliance as per TOPs P4
Gain access to PCB
Use insulation mat as required
Gain access to PCB
Use insulation mat as required
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
With the fan running measure DC voltage at the PCB test pin between the yellow wire at connector J4 on the PCB and a suitable earth point.
Expect approx 12V DC.
Expect approx 12V DC.
Isolate as per TOPs P4
and refit as necessary