Dexter Laundry T-350 Parts & Service Manual page 52

Ignition System-Function & Sequence
During normal dryer operation, the following occurs:
1. The dryer electronic control calls for heat.
2. If the drive motor is running, the blower motor safety circuit provides power to the electronic
control. If the control senses that the heat should be on, a circuit is closed allowing power
through the high limit thermostat, air flow switch.
3. Once the flame is established, the sensing electrode detects the presence of flame and the
sparking stops.
4. If for any reason the flame is not established in a period of 10 seconds, the electronic control
will try this sequence for 3 tries. Normally the 10 seconds "Trial For Ignition" period is ample to
establish and prove flame.
5. If the flame is shutdown or blown out during operation, the ignitor will immediately go into "Trial
For Ignition" again for 10 seconds.
6. However, at the end of 3 separate retries of 10 seconds "Trial for Ignition", the flame is not
established, the ignition system goes into "Safety Lock-Out" and will not reactivate the "Trial for
Ignition" until there is a current interruption for a period of 15 seconds. This interruption can be
provided by opening the dryer loading door and allowing the machine to come to a complete stop
for 15 seconds.
Ignition System-Checkout
1. If flame is present during "Trial For Ignition" period but the system shuts down, there may be
an improper ground. The entire ignition system is grounded together including the electrode
assembly, the electrode mounting bracket, the burners and the burner bracket. Shutdown can
also occur if for some reason the system isn't sensing the flame. Check the sensor for damage
and check the connections of the sensor lead.
2. If there is no spark or intermittent spark, check black hi-voltage lead wire for damage or cracks in
insulation. (This lead wire must not be taped or connected to any metal edges along its length to
prevent pinching and arcing. Also, do not bundle this wire with other wires.)
NOTE:
Spark gap and electrode location are important. If the electrode is damaged or mounting
Spark Electrode Assembly-Removal
1. Remove electrode cover and disconnect wires to electrodes.
2. Remove two screws to detach electrode assembly.
Gas Valve Removal
valve)
1. Disconnect union at gas valve and disconnect wires from gas valve operator coils.
2. Remove right manifold mounting bracket screws and slide manifold to remove from left bracket.
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is changed the spark gap may not be correct for ignition to occur. Check for cracks in
the ceramic insulator. Replace electrode assembly if necessary. Also check for carbon or
foreign material on the electrodes and clean if necessary.
(shut off manual gas valve to stop gas flow before removing gas control