Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Selector Switch to Hot Water and Heating
Remove the flame sense lead from terminal X501
Remove the flame sense lead from terminal X501
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Using shrouded probes measure the voltage across
terminals at X501 and X500 on the PCB.
Expect approx. 70 V AC.
Note:
This voltage should be present
regardless of which stage the boiler is in.
terminals at X501 and X500 on the PCB.
Expect approx. 70 V AC.
Note:
This voltage should be present
regardless of which stage the boiler is in.
Isolate as per TOPs P4
and refit as necessary