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Gas Valve
LG Electronics Training Center, LGEAI, U.S.A.
Sequence of Ignition in a Gas Dryer
User selects cycle, loads wet cloths into dryer, shuts the door and starts the dry cycle.
X2 relay on the PC Board closes and L1 is supplied for the motor circuit at WH4 pin 3 on the PC Board.
IF the Broken Belt Switch, Blower Thermostat and the Motor Overload Protector are all
closed, L1 energizes the both the motor's run & start windings competing the circuit through the
closed contact at pins 1 & 2 at the door switch and through the Neutral side of the line. .
With in a fraction of a second, the Centrifugal Switch Contacts go from NC to NO. The opening of the
NC contact accomplish two important steps. The first step is to drop out the Start Winding, who's
assistance in starting the motor is no longer needed. Secondly, with the motor now rotating the
contacts at the Centrifugal Switch now close to complete the Heating Circuit.
With the High Limit & the Safety thermostat and the Flame Sensor closed, the heating circuit now
has a path to neutral for the dryer's Igniter . At this point since the Tap Relay Black has not
closed , the Igniter is not yet energized , but the PC board closes the contacts at BL3 pin 1&2
At this point the PC board closes the contacts at the Tap Relay Black at the PCB which in turn
energizes the Igniter. The intense heat from the Igniter will eventually open the contacts of the
Flame Sensor at 370°
igniter is hot enough to ignite the gas by way of a feed back signal at YL3 pin 2 and energizes
Valve 2 from BL3 pins 1 &3. With both valve now opened, gas flows across the still hot igniter
and we have IGNITION. This process will repeat numerous times through out the drying cycle as
the dryer's thermistor feeds temperature readings to the PC board which then will cycle the gas
LG Electronics Training Center, LGEAI, U.S.A.
The two Gas Valve Solenoid Coils
are 90V dc 1.5 to 2.5 kΩ
Tap Relay Black
Tap
Burner
Relay 1
High
Mid
High
Medium
Low
Extra
Low
91
sending 90Vdc to Valve 1.
F
opening the circuit to the Igniter . Now the dryer PC board has verify the
valves on and off to maintain the correct temperature setting.
92
Valve 1
Valve 2
Remark
Temperature Control below 70± 4° F (158°F)
Turns burner on
Temperature Control below 47± 4° F (116.6°F)
Turns burner on
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