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on the electronic control board. The COM. terminal pro-
vides power to the common contact of the relay and also
provides power to the electronic control board. The elec-
tronic control board controls the operating temperature
of the dryer and length of the cycle by either sensing the
amount of moisture in the clothes or a fixed amount of
time when time dry is used.
Note:
If the red and black wires on the relay are
reversed, the control will not operate.
Always connect the red wire to the
terminal mark COM.
Note:
For information on programming the
electronic control and the cycles refer to
section A.
Electronic Control Board Circuits:
Line 1 is applied to the control board at the common
terminal of RL 2 and neutral on pin 1 of the six pin plug.
The control board receives inputs from the membrane
switches which programs the control, the contact sen-
sors that senses the amount of moisture in the clothes
and the control thermistor which senses the tempera-
ture in the dryer. The control board use these input to
control the drive motor circuit by open and closing the
contacts of relay RL 1 and the heater circuit by opening
and closing the contracts of relay RL 2.
Drive Motor Circuit:
When power is connected to the dryer, line 1 is applied
through the thermal limiter (a non-resettable fuse
mounted on the rear wall of the dryer) to the COM. termi-
nal of the door switch.
When the door is closed the COM terminal is connected
to terminal NO. of the door switch. From terminal NO.
power is applied to terminal J13 of the motor relay RL 1
on the control board. When the control board closes
relay RL 1 power is applied through terminal J9 to termi-
nal M4 of the drive motor.
Terminal M4 is connected inside the motor to one side
of the thermal overload. (The thermal overload protects
the motor from being damaged by overheating.) The
other side of the thermal overload is connected to one
end of both the run winding and the start winding of the
drive motor. When the motor is not turning, the other
end of the start winding is connected internally to termi-
nal M5 of the motor through the NC contact of the motor
centrifugal switch. The other end of the run winding is
also connected internally to terminal M5.
When the motor is not turning, the start winding and
the run winding are connected in parallel. When the
contacts of relay RL 1 are closed, with the dryer door
closed, line 1 and neutral voltage is applied across both
the start and run windings of the drive motor. With power
applied to both the start and run windings, the motor
starts to turn.
When the speed of the motor reaches about 80% of
it's normal run speed the contacts of the centrifugal switch
remove power from the start winding thus removing the
start winding from the circuit.
The drive motor preforms two tasks in the dryer. A pul-
ley attached to one end of the motor shaft uses a belt to
drive the dryer drum. The blower wheel is attached to
the other end of the motor shaft to pull the air through
the clothes and force it out the exhaust vent.
Temperature Sensing Circuit:
The temperature in the dryer is controlled by the control
thermistor and the electronic control board. The control
thermistor is mounted in the blower fan housing and is a
negative coefficient thermistor that decreases in resis-
tance as the temperature increases.
The electronic control board reads the resistance of the
thermistor and converts it into temperature.
43
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