Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow fan to run.
Measure the DC voltage between pin 3 (Black) on connector X20 and a suitable earth.
Expected voltage approximately 5.6 Vdc.
Note:
Each pin on the PCB connector is numbered.
Measure the DC voltage between pin 3 (Black) on connector X20 and a suitable earth.
Expected voltage approximately 5.6 Vdc.
Note:
Each pin on the PCB connector is numbered.
 pcb in situ.gif)
 connector x20 on pcb.gif)
Isolate as per TOPs P4
and refit as necessary