15
6. SPARK GENERATOR
The spark generator is located as a separate component on the gas valve and has two
functions.
1. To produce a high tension voltage to produce an ignition spark at the electrode
2. To supply the 230V ac from the PCB to the main gas valve solenoids. (See section
7&8)
The 230V ac fed from J8 (brown) is transformed to HT voltage by the spark generator and
the maximum duration of the spark is 18 seconds in 3 x 6 second sequences. The supply
voltage to the spark generator from the PCB ceases as soon as the ionisation electrode
detects the main burner flame has been established. The unit can be removed from the
gas valve by removing the forward facing self tapping screw located on the top of the unit,
this will then allow the unit to be unplugged from the gas valve.
N. B. Care must be taken when replacing the unit not to damage or bend the pins on the
gas valve solenoid.
7. & 8. GAS VALVE SOLENOIDS
The gas valve is fitted with twin solenoids moulded into a single removable unit. In order
for the gas valve to open and allow gas to the burner, both of the solenoids must be
energised. The supply voltage for this action is 230V ac and supplied from J8 (red / black)
on the PCB
To remove the solenoid from the gas valve remove the spark generator (see above) then
remove the central locating screw, this will allow the solenoid to be pulled away from the
gas valve.
N.B. faulty solenoids can be replaced, without the need to replace the complete gas valve.
(Part Number FCB 1501).
Nominal resistance values for the solenoids can be taken from the disconnected spark
generator plug J8.
EV1 = 0.84 kOhms (nominal) between black and blue (pins 4 and 3 on solenoid).
EV2 (small) = 7.00 kOhms (nominal) between red and blue (pins 1 and 3 on solenoid).
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