Sunday, December 20, 2015

AX-1100(R)M - AX-1100(SL)M - Sharp MICROWAVE OVEN - FUNCTION OF IMPORTANT COMPONENTS

AX-1100(R)M - AX-1100(SL)M - Sharp MICROWAVE OVEN WITH STEAM AND GRILL - Circuit diagram and other components - FUNCTION OF IMPORTANT COMPONENTS [Contn:]
DOOR OPEN MECHANISM
1. The door lever is gripped and the door open handle is pulled.
2. The latch head L is lifted up by the door lever.
3. The latch head U is lifted up by the linked latch lever.
4. Now both latch heads are lifted up, so they can be released from the latch hook.
5. Now the door can be opened.
SWITCH
MONITORED INTERLOCK SWITCH SW1
1. When the oven door is closed, the contacts (COM-NO) of the switch must be closed. And the contacts (COM-NC) must be opened.
2. When the oven door is opened, the contacts (COM-NO) of the switch must be opened. And the contacts (COM-NC) must be closed.
MONITOR SWITCH SW2
The monitor switch is activated (the contacts opened) by the latch head U on the door while the door is closed. The switch is intended to render the oven inoperative by means of blowing the fuse F2 F8A when the contacts of the monitored interlock switch SW1 fail to open when the door is opened.
Function
1. When the door is opened, the contacts (COM-NC) of monitor switch SW2 close. At this time the contacts (COM-NO) of monitored interlock switch SW1 are open.
2. As the door closed, the monitor switch SW2 contacts (COM-NC) are opened.  The contacts (COM-NO) of monitored interlock switch SW1 and door sensing switch SW3 are closed (On opening the door, each of these switches operate inversely.).
3. If the door is opened and the monitored interlock switch SW1 contacts (COM-NO) fail to open, the fuse F2 (F8A) blows immediately after closing of the monitor switch (COM-NC) contacts.
CAUTION: BEFORE REPLACING A BLOWN FUSE F2 F8A, TEST THE MONITORED LATCH SWITCH SW1 AND MONITOR SWITCH SW2 FOR PROPER OPERATION
DOOR SENSING SWITCH SW3
1. When the oven door is closed, the contacts (COM-NO) of the switch must be closed.
2. When the oven door is opened, the contacts (COM-NO) of switch must be opened
INTAKE DAMPER SWITCH SW4
The intake damper switch is turned on and off by the air damper cam which is rotated by the intake damper motor.
ANTENNA SWITCH SW5
The antenna switch is turned on and off by the shaft assembly which is rotated by the antenna motor.
FUSE
FUSE F1 20A 250V
If the wire harness or electrical components are short-circuited, this fuse F1 blows to prevent an electric shock of fire hazard.
FUSE F2 F8A 250V
1. If the wire harness or electrical components are short-circuited, this fuse blows to prevent an electric shock or fire hazard.
2. The fuse also blows when the monitored interlock switch SW1 remains closed with the oven door open and when the monitor switch SW2 contact (COM-NC) closes.
3. The fuse also blows when the asymmetric rectifier, H.V. rectifier, H.V. wire harness, H.V. capacitor, magnetron or secondary winding of high voltage transformer is shorted.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is solid state device that prevents current flow in both directions. And it prevents the temperature rise of the high voltage transformer by blowing the fuse F2 F8A when the high voltage rectifier is shorted.
The rated peak reverse voltage of D1 of the asymmetric rectifier is 6 kV The rated peak reverse voltage of D2 of the asymmetric rectifier is 1.7 kV. D1 and D2 of the asymmetric rectifier or high voltage rectifier are shorted when the each peak reverse voltage goes beyond the each rated peak reverse voltage. (The process of the blowing the fuse F2 F8A.)
1. The high voltage rectifier is shorted by some fault when microwave cooking or dual cooking.
2. The peak reverse voltage of D2 of the rectifier goes beyond the rated peak reverse voltage 1.7 KV in the voltage doubler circuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high voltage winding of the high voltage transformer.
5. The large electric currents beyond 8A flow through the primary winding of the high voltage transformer.
6. The fuse F2 F8A blows by the large electric currents.
7. The power supplying to the high voltage transformer is cut off.
THERMAL CUT-OUT
THERMAL CUT-OUT TC1 145
°C (MG)
This thermal cut-out protects the magnetron against overheat. If the temperature goes up higher than 145
°C because the fan motor is interrupted or the ventilation openings are blocked, the thermal cut-out TC1 will open and the oven will switch off. The defective thermal cutout must be replaced with a new one.
THERMAL CUT-OUT TC2 170°C (OVEN)
This thermal cut-out protects the oven against overheating or fire inside the oven. If the temperature rises above 170
°C the thermal cutout opens the oven will switch off. The defective thermal cut-out must be replaced with a new one.
THERMAL CUT-OUT TC3 170
°C (ENGINE)
This thermal cut-out protects the engine unit against overheating. If the temperature rises above 170
°C the thermal cut-out opens the oven will switch off. The defective thermal cut-out must be replaced with a new one.
 NOISE FILTER
The noise filter assembly prevents radio frequency interference that might flow back in the power circuit.
HEATING ELEMENT
1. GRILL HEATING ELEMENT GH
The grill heating element is provided to brown the food and is located on the top of the oven cavity.
2. ENGINE UNIT (ENGINE HEATING ELEMENT) EH
The engine unit is provided to generate the steam
MOTOR
1. ANTENNA MOTOR AM
The antenna motor rotates the antenna located under the oven cavity.
2. FAN MOTOR FM
The fan motor drives a blade which draws external cool air. This cool air is directed through the air vanes surrounding the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and vapours given off from heating food. It is then exhausted through the exhausting air vents of the oven cavity.
3. INTAKE DAMPER MOTOR DM
The air damper position is set automatically by the intake damper motor, intake damper switch, air damper cam and damper shaft. These components are operated by a signal that judges the selected cooking mode by the control unit.
4. PUMP MOTOR (TUBE PUMP ASSEMBLY)
The tube pump assembly consists of the pump motor, roller and tubes. The pump motor rotates the roller. The roller presses the tube. The water in the tube is pressed out from the tube pump assembly.
THERMISTOR
1. THERMISTOR (ENGINE) TH1
The thermistor is a negative temperature coefficient type. The temperature in the engine unit is detected through the resistance of the thermistor, and then the control unit causes the relay to operate, thus the current to the engine heating element is turned ON/OFF.
2. THERMISTOR (GRILL) TH2
The thermistor is a negative temperature coefficient type. The temperature in the oven cavity is detected through the resistance of the thermistor, and then the control unit causes the relay to operate, thus the current to the grill heating element is turned ON/OFF.
Circuit diagram and other components