Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Selector Switch to Hot Water and Heating
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset appliance as necessary.
Using shrouded probes measure the voltage across
terminals at X501 and X500 on the PCB
Expect approx. 70 VAC before the flame is present.
Then when the flame lights the voltage should drop to approx. 59 VAC.
Using shrouded probes measure the voltage across
terminals at X501 and X500 on the PCB
Expect approx. 70 VAC before the flame is present.
Then when the flame lights the voltage should drop to approx. 59 VAC.
Isolate as per TOPs P4
and refit as necessary