Garland AIR-DECK GAS BAKE AND PIZZA OVENS - Manuel (Page 14)

Part # 1382670 (12/07) Page 14
INTERMITTENT PILOT INSTRUCTIONS Continued
Note: If the ground circuit path is incomplete the S86C, D, G
and H system control will allow one trial-for-ignition before
going into safety lockout.
Electrical grounding connections at the pilot burner,
ignitor/sensor and S86 must be clean and tight. If lead wire
is damaged or deteriorated, use only No. 14 of 18 gauge,
moisture-resistant, thermoplastic insulated wire with
105C. (221 F) minimum rating as replacement. Excessive
temperature at the ceramic flame rod insulator can also
permit electrical leakage to ground. Examine the flame rod
and mounting bracket, and correct if bent out of position.
Replace Q345, Q346 Q348 or ignitor/sensor if insulator is
cracked.
Check Spark Ignition Circuit
The electronic module and step-up transformer in the S86
provides spark ignition at 15,000 Volts (open circuit). This
circuit can be checked at the S86 module as follows:
1. Turn off the manual gas cock to prevent the flow of gas.
2. Disconnect the ignition cable at the S86 stud terminal to
isolate the circuit from the pilot burner/ignitor/sensor,
and prepare a short jumper lead using heavily insulated
wire, such as ignition cable.
3. Energize the S86, touch one end of the jumper firmly to
the S86 ground terminal (GND). Do not disconnect the
existing ground lead. Move the free end slowly toward
the stud terminal to establish a spark and then pull the
lead wire slowly away from the stud. Note the length of
the gap at which arcing stops.
CAUTION: Do not touch either stripped end of jumper or
stud terminal. This is a very high voltage circuit and electrical
shock can result. Perform the test immediately upon
energizing the system – before the S86C,D,G goes into safety
lockout and interrupts the spark circuit.
4. An arc length of 1/8” (3.2 mm) or more indicates
satisfactory voltage output. Replace the S86 if not arc can
be established or the maximum gap is less then 1/8” (3.2
mm), and the fuse and power to the S86 input terminal
was okay.
Control Module Flame Sensor Circuit
The control module provides AC power to the ignitor/sensor
which the pilot burner flame rectifies to direct current. If the
flame signal back to the control module is not at least 1.5 μA
DC, the system will lockout. The output of the flame sensing
circuit cannot be checked directly, so check the flame
sensing circuit indirectly by checking the flame sensing
current from the ignitor/sensor to the control module as
follows.
1. Connect a meter (DC micrometer scale) in series with
the flame signal ground wire as shown below. Use the
Honeywell W136A Test Meter, or equivalent. Disconnect
the ground wire at the control module.
Connect the red (positive) lead of the meter to the free
end of the ground wire. Connect the black (negative)
meter lead to the quick-connect ground terminal on the
control module.
2. Restart the system and read the meter. The flame sensor
current must be at least 1.5μA, and the reading must be
steady. If the reading is below the value designated or the
reading is unsteady, check the pilot flame and electrical
connections as described above. Also, replace the ignitor/
sensor if the ceramic insulator is cracked.