TM 10--3510--221--10
0007 00--4
CONTROL SYSTEM THEORY
OF OPERATION -- Continued
0007 00
SOLENOID VALVE CONTROL
When the SSR receives a 5 VDC input signal from PCB9, through PCB7, the SSR switches and applies 110 VAC or
12 VDC power to the appropriate solenoid. When the 5 VDC signal is removed the SSR switches and power is
removed from the solenoid.
HEATER CONTROL
When control power is applied to the LADS, power is applied to the flame programmer. When this occurs the flame
programmer will go through an initiate sequence to verify the correct voltage is present then switches to stand--by
mode. In stand by mode the flame programmer waits for a call for heat signal from the control system. When heat is
required an SSR on PCB3 receives a 5 VDC input signal from PCB9, through PCB7. The SSR switches and applies
110 VAC to the heater control relay (CR300). The heater control relay then applies 110 VAC to the call for heat
contact of the flame programmer. The flame programmer starts a purge sequence by applying 110 VAC to the coil of
the burner blower contactor. Once burner blower operation and presence of fuel pressure are verified by the flame
programmer the programmer will switch to the ignition sequence. The ignition sequence consists of energizing the
fuel solenoid valves and ignition transformer. Once ignition occurs, and is verified, the flame programmer
de--energizes the ignition transformer and switches to the run mode. In the run mode the flame programmer monitors
the heater interlock circuit and call for heat signal. When heat is not required PCB9 will remove the 5 VDC signal to
the SSR. The SSR switches removing the call for heat signal from relay CR300 and the flame programmer. The
flame programmer de--energizes the fuel solenoid valves and the blower contactor and returns to the standby mode.
OPERATOR INTERFACE
Main power and control power are applied to LADS at the main control enclosure. At the operator panels the operator
uses pushbutton switches, indicating lights, an alarm, and a message display to control and monitor LADS operation.
Operator panels A and B are used to selecting laundry formulas and to start and stop laundry cycles on their assigned
washing/drying systems. Operator panel A is used to drain, fill, and heat water tanks on both washing/drying systems
and control operation of the air system. Operator panel A is also used by maintenance personnel to observe system
alarms, monitor operating parameters, and initiate specific system or component tests. Communication between the
operator panels and PCB9 is accomplished using several methods. Selection of menu options and turning off the
alarm is done using pushbutton switches. These switch communicate with PCB9 as previously discussed under
switching device monitoring. Indicator lights and the audible alarm are turned on when an SSR receives and input
signal from PCB9 through PCB7. When the 5 VDC signal is removed the SSR switches and power is removed from
the indicator. The display contains its own processing circuit that communicates digitally with PCB9. An interface
card PCB10 provides an interconnection between the display and PCB9. PCB10 also provides +12 VDC power from
PS2 to the display backlight. There are four alarm levels associated with LADS operation. When the system is
operating normally the alarm is off. If the alarms comes on, and remains steady, this indicates that some type of
operator action is required (i.e., close doors, laundry, cycle is complete, add FRS, etc.). If the alarm comes on with a
slow pulse a non--critical fault has occurred. If the alarm comes on with a fast pulse a critical fault has occurred and
LADS operation will be shut down by the control system.
