Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Gain access to PCB (use Insulation Mat as required)
External controls calling
External controls calling
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure AC volts between the terminal
marked 4 and N on connector X1 on the PCB
(as shown in the photograph).
Mains voltage should be measured.
Note:
If no external controls are installed a link should be fitted between locations 3 & 4 on the main terminal.
marked 4 and N on connector X1 on the PCB
(as shown in the photograph).
Mains voltage should be measured.
Note:
If no external controls are installed a link should be fitted between locations 3 & 4 on the main terminal.
Isolate as per TOPs P4
and refit as necessary