TM 5-6675-324-14
Power circuits.
Consists of the following circuits and components:
m.
Drum Heater Control Circuit (1)
Fan Motor Control Circuit (2)
Power Supplies (3)
(1) Drum heater control circuit.
The heater is incorporated inside the drum shaft to maintain the photosensitivity of
the drum, regardless of external temperature and humidity changes. Current of 120
V, 60 Hz is applied through LF1 to door switches MS1 and MS2. If the upper assembly
or the front panel is open, the switches open, interrupting primary power. When
both switches are closed, power is applied to circuit breaker CB1. If the tempera-
ture is below 60.8F (16 C), thermal switches TS1 and TS3 close, applying full power
to heater H1. When the temperature rises above 105.8F (41C), both switches open
and the heater is off. Between 73.4F (23C) and 95F (35C), TSI is closed, TS3 is
open, and half-wave rectified power is fed to the heater.
(2) Fan motor control circuit. When power switch SW1 and door switches MS1
and MS2 are closed, primary power is applied to transformer LVT1, enabling the 24
V dc supply which energizes K301. This energizes exhaust fans FM2 and FM3. SQ301 is
a noise filter. When DRMD = 1, solid- state relay Q301 is enabled, energizing the
main motor and intake fan FM1. When the power switch is off and the temperature is
above 131F (55 C), thermal switch TS2 closes, enabling exhaust fans FM2 and FM3.
When the temperature decreases below 113 F (45C), the thermal switch opens. An
activated carbon filter between the exhaust fans and halogen lamp absorbs ozone
that is generated by the corona units so that it cannot enter the atmosphere.
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