Quarter 4 Rice Cooker Maintenance and Repair PDF

**Content Standard** - Rice Cooker - UNIT OF COMPETENCY: MAINTAIN AND REPAIR ELECTRONICALLY CONTROLLED DOMESTIC APPLIANCE ------------------------------------------------------------------------------------ I. **INTRODUCTION:** II. **PRE/ DIAGNOSTIC ASSESSMENT** 1. Open the circuit when...

**Content Standard** - Rice Cooker - UNIT OF COMPETENCY: MAINTAIN AND REPAIR ELECTRONICALLY CONTROLLED DOMESTIC APPLIANCE ------------------------------------------------------------------------------------ I. **INTRODUCTION:** II. **PRE/ DIAGNOSTIC ASSESSMENT** 1. Open the circuit when the temperature has gone unusually high. A. Center Thermostat B. Thermal Fuse 2. Prevents the rice cooker from being turned on without the pan. B. Center Thermostat B. Thermal Fuse 3. Turns off the cooking cycle and starts the warming cycle. C. Center Thermostat B. Thermal Fuse 4. A part of a control system used to monitor the output. D. Sensor B. Comparator 5. A system that compares the output with the expected result. E. Closed Loop System B. Open Loop System 6. A test conducted to see if the rice cooker will turn-off 1 minute or after the generation comes to a stop. F. Bubbling Test B. Evaporation Test 7. A kind of test to see if the heating element is in good condition. G. Bubbling Test B. Evaporation Test 8. A test conducted to see the alignment and sufficiency of the heating plate on the pan. H. Bubbling Test B. Evaporation Test 9. The metal and magnet will pop apart when this temperature is reached. I. 65 ˚C B. 134 ˚C 10. The boiling point of water. J. 65 ˚C B. 134 ˚C III. **LEARNING COMPETENCIES** LO1: PREPARE UNIT, TOOLS, EQUIPMENT AND WORKPLACE FOR MAINTENANCE/REPAIR(RICE COOKER) ------------------------------------------------------------------------------------- - Prepare necessary tools, test instruments and personal protective equipment in line with job requirements. - Acquire service manuals and service information required for repair/maintenance as manufacturer's specifications. - Conduct complete check-up of electronically-controlled domestic appliances. - Document the identified defects based on check-up conducted. INFORMATION SHEET 1.1 --------------------- -- -- -- -- -- -- INFORMATION SHEET 1.2 OPERATION OF AN ELECTRIC RICE COOKER ---------------------------------------------------------- ##### Principle of operation (basic rice cooker models) ##### Basic Parts of Electric Rice Cooker ##### Exploded Views 11. Switch Assembly 12. Switch Panel 13. Decorative Panel 14. Lamp Board Assembly 15. Switch Lever 1 Lid ##### Sample Schematic Diagram of a Rice Cooker ##### Function of Center Thermostat and Thermal fuse  ##### Wiring Diagram of an Electric Rice Cooker ##### Switch-On Preventive System 1. Normally when the pan is inserted properly into the rice cooker, the pan will depress the center thermostat. The center thermostat outer spring will be compressed causing the switch button to depressed, and then the following will happen: a. The auxiliary lever will activate the micro-switch button. This puts the micro-switch in the cook position. b. The switch lever will push the rod which will allow the magnet to meet with the metal. c. When the rice is cooked and the proper temperature has been reached (134°C ± 6°C), the metal and magnet will pop apart. d. The rod will push the switch lever and cause micro-switch to turn in warming position. 2. When the pan is not in place within the rice cooker, the center thermostat is not depressed. a. In this condition, the outer spring is not compressed within the center thermostat preventing the metal from reaching its normal operating position. b. When the switch button is depressed, the switch lever and auxiliary lever work as above but the magnet cannot come in contact with the metal to hold the switch lever in the cook position. c. When the pressure is taken off the switch button, the switch lever releases immediately to the open or warm positions. ##### Thermal Fuse SELF CHECK 1.2 -------------- -- -- -- -- INFORMATION SHEET 1.3 --------------------- **ELECTRONIC CONTROL SYSTEMS USED IN RICE COOKER** ### Open Loop System ##### Open Loop System Diagram ### Closed Loop System ##### Closed Loop System Diagram ACTIVITY 1.1 ------------ **HEAT SENSOR (SIMPLE FIRE ALARM)** ##### Circuit Diagram of the Fire Alarm ##### Resources: -- -- -- -- -- -- ##### Procedure: 1. Connect the components to the breadboard following the diagram and observing the correct pins of the components. For breadboard care thermistor should not be placed on the breadboard. 2. Power-up and test your project by placing a lighted match or candle near the thermistor. To adjust sensor sensitivity you may want to adjust VR1. 3. If your project failed to work, review the procedures and/or check the condition of battery or power supply and other electronic components. ##### Criteria for Functional Project ----------- -- -- -- -- -- -- -- **TOTAL** ----------- -- -- -- -- -- -- -- -- -- -- -- ACTIVITY 1.2 ------------ ##### Resources: ##### Procedure: 1. Conduct an initial interview to the owner of the appliance. - Ask what the problem is. - Request for the details of the problem (how does it happen/since when/ nature of the problem) 2. As serviceman, you must confirm the problem/ complain. 3. Make an initial inspection/ testing of the appliance. - Physical appearance - Operating controls - Power cord... 4. Take note of the information gathered and observed. 5. Accomplish Receiving and Repair Form. ##### Receiving and Repair Form -- -- -- -- -- -- PERFORMANCE CHECK 1.1 RECEIVING ELECTRONICALLY-CONTROLLED DOMESTIC ------------------------------------------------------------------ +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | - Lid Assembly | | | +-----------------------+-----------------------+-----------------------+ | - Aluminum Pan | | | +-----------------------+-----------------------+-----------------------+ | - Handle | | | +-----------------------+-----------------------+-----------------------+ | - Thermostat | | | +-----------------------+-----------------------+-----------------------+ | - Body | | | +-----------------------+-----------------------+-----------------------+ | - Power Cord/Switch | | | +-----------------------+-----------------------+-----------------------+ LO2. DIAGNOSE FAULTS OF ELECTRONICALLY-CONTROLLED DOMESTIC APPLIANCE (RICE COOKER) ---------------------------------------------------------------------------------- - Observe systematic pre-testing procedure in accordance with manufacturer's instructions - Check and isolate circuits using specified testing procedure - Document results of diagnosis and testing accurately and completely within the specified timeframe - Explain identified defects and faults based on the result of diagnosis and testing - Provide data/information regarding the status and serviceability of the units as per procedure. #### INFORMATION SHEET 2.1 1. Determine the specific problem by asking the symptom. a. Ask the owner/operator of the electric rice cooker of what is the symptom of the unit. b. Request for the detail of the symptom (how does the symptom happen) and how long it has been observed. 2. Operate the device. Make sure that you know how to operate an electric rice cooker. If not, review the operating manual as well as service manual (if available) of the unit prior to its testing and operation c. If you have worked on the same unit before, test out to see if it operates in the same way. d. Determine the last time it has been modified/repaired. e. You must recognize the symptom/ complain of the owner to the unit. 3. Perform visual inspection of the unit. f. Prepare the tools needed and remove the cover ready for inspection. g. Apply careful physical inspection of the parts/components. (Look for burned and broken components; Inspect for loose connections or broken wires) 4. If all looks fine, test the unit for resistance checks. h. Get the multitester and set it at range Rx1Connect the test probes to each of the plug terminal, the reading must be very high since you are measuring the resistance of the keep warm heater having the temperature control at zero position. i. Then, turn-on the cook switch, make sure that you have properly inserted or placed the pan into the rice cooker with enough weight to depress the center thermostat, decrease in resistance should be observed since the cook heater will be activated. If this happen, the unit might be in good condition. For safety, place one probe across to the plug terminals and the other probe to the body. There should be very high (infinite) resistance. Proceed to checking for consistency of heat. If there's something different, refer to troubleshooting guide o this lesson. 5. Record your findings for future reference. ##### Checking for Consistency of Heat (Rice Cooker is Energized) 1. Bubbling Test a. Fill water until the center area of the pan bottom is dipped, and close the lid. Then turn the cook switch on.  b. When it is already producing steam, remove the lid and immediately check the bubbling condition on the pan bottom. Bubbling Condition A. Bubbles generate throughout the circumference of the pan bottom- Good B. Bubbles generate only on certain part of the pan bottom-Bad 2. Evaporation Test 1. Cover the entire pan bottom with 2 or 3 pieces of tissue paper (or gauze), and turn on the switch subsequently. Make sure you put enough weight on the pan so you can turn on the switch, a 5x5x40cm lumber or piece of wood will be fine.  2. The cooker is considered acceptable if it turns-off automatically 1 minute before or after the steam generation comes to a stop. If these requirements are not satisfied, check the center thermostat as well as the contacted condition between the pan bottom and the cooking heater, and then repair or replace the parts if necessary. ##### Diagnosing and Troubleshooting Procedure/ Guide: -- -- -- -- -- -- -- -- ---------------------------- **CORRECTIVE MEASURE** Replace center thermostat. -- -- ---------------------------- -- -- ------------------------------- **CORRECTIVE MEASURE** Adjust or align switch lever. -- -- ------------------------------- -- -- -- -- -- -- ACTIVITY 2.1 ------------ **PRE-TESTING AND TROUBLESHOOTING A RICE COOKER** ##### Resources: ##### Directions: 1. Let one of your classmates act as the owner of the appliance. 2. Accomplish Receiving and Repair Form in your notebook, record the progress of your activity. 3. Perform the procedures in accepting appliance 4. Repair defective rice cooker. ##### Receiving and Repair Form -- -- -- -- -- -- -- -- -- -- -- -- PERFORMANCE CHECK 2.1 --------------------- ----------- -- -- -- -- -- -- -- **TOTAL** ----------- -- -- -- -- -- -- -- -- -- -- -- LO3: MAINTAIN AND REPAIR ELECTRIC RICE COOKER --------------------------------------------- - Use PPE in accordance with OHS practices - Perform repair activity within the required timeframe - Observe safety precautions in handling the unit/product as per standard operating procedure - Replace defective parts/ components with identical parts or recommended parts with equivalent ratings - Solder/mount repaired or replaced parts/components in accordance with industry standards - Clean unit in accordance with standard operating procedure #### SELF CHECK 3.1 PERSONAL PROTECTIVE EQUIPMENT -- -- -- -- -- -- -- -- INFORMATION SHEET 3.1 REMINDERS FOR COMPONENT REPLACEMENT --------------------------------------------------------- 1. Determine the description of the values and ratings of the individual defective parts using the manufacturer's service manual. 2. Identify the sources of the replacement components/parts. - Original replacement components from the original factory sources - Universal replacement components from independent factory sources 3. Consider the following factors in selecting parts. - **Quality**. The ability to provide exact value or specification to replacement part. - **Tolerance**. The ability to provide exact value or acceptable parameters to replacement parts. - **Availability**. The local access to parts and whether the parts are available. - **Price.** Refers to the affordability of the replacement parts at a reasonable price. 4. Disconnect or remove properly the electrical/mechanical parts of Rice Cooker 5. Install correctly the replacement parts and other components. 6. For burnt components where values are impossible to recognize, secure a schematic diagram or service manual if possible. In other case, you can look for the same brand and model as reference. 7. Double check the testing procedure in suspected defective components. 8. Check the nearby components for possible consequence of being damaged too. 9. Consider the original orientation/connection of the components in replacing defective one. 10. Observe safety at all times. INFORMATION SHEET 3.2 TROUBLESHOOTING, MAINTENANCE AND CLEANING TIPS -------------------------------------------------------------------- 1. Conduct a *quick* diagnosis of the trouble symptom and repair the defective set in the *shortest possible time*. Do not troubleshoot Rice Cooker unless you have determined the fault. 2. Secure a circuit diagram. 3. If the Rice Cooker doesn't heat, make sure there is power on the outlet, check the [electrical cord](http://www.fixitclub.com/parts-components-repairs/electrical-cord-repair/), and check the thermostat thermal fuse. 4. Always suspect a faulty contact on mechanical switch circuit rather than defective electronic/electrical parts. 5. If the Rice Cooker produces too much or too little heat, test the [electrical cord](http://www.fixitclub.com/parts-components-repairs/electrical-cord-repair/) for loose wiring and connection. Also test and, if needed, adjust calibration of the thermostat. 6. Use Personal Protective Equipment. 1. Turn-off and unplug the electric Rice Cooker and make sure it's already cool before cleaning. 2. Check the owner's manual for your Rice Cooker to learn the specified manufacturer's suggestions for cleaning. 3. You may use a sponge and commercial cleaner or baking soda and water to remove dirt buildup on the external parts. Don't submerge a Rice Cooker in water or cleaning liquid. ##### Resources: ##### Directions: 1. Provided with the resources, perform the maintenance/repair procedure. Observe safety precautions at all times and consider the information given in this lesson. 2. Let one of your classmate acts as the owner of the Rice Cooker. 3. Perform the procedures in accepting and pre-testing an appliance. 4. Accomplish the Receiving and Repair Form and the Maintenance and Repair Form as you perform the activity. 5. Provide information regarding the status and serviceability of the appliance. 6. Forty minutes will be allotted for this activity. ##### Receiving and Repair Form -- -- -- -- -- -- -- -- -- -- -- -- PERFORMANCE CHECK 3.1 MAINTAIN AND REPAIR A RICE COOKER ------------------------------------------------------- ----------- -- -- -- -- -- -- -- **TOTAL** ----------- -- -- -- -- -- -- -- -- -- -- -- LO4: REASSEMBLE AND TEST REPAIRED APPLIANCES -------------------------------------------- INFORMATION SHEET 4.1 --------------------- #### REASSEMBLING AND TESTING AN ELECTRIC RICE COOKER 1. After replacing the defective part of the appliance, prepare the parts for reassembling. Make sure that there are no missing part or component and as well as the screws. 2. Review the operating and service manual if available. 3. Fix all the disassembled parts in the housing/compartment, considering the fittings, lock etc. 4. Wires should be in their proper places and loose parts should be tighten to avoid damaged due to misalignment. 5. All sides of the housing should fit. See to it that all movable parts are moving appropriately. 6. Clean the unit before doing the testing procedure. 1. Get the multitester and set it at range Rx1. Connect the test probes to each of the plug terminals; the reading must be very high since you are measuring the resistance of the keep warm heater having the temperature control at zero position. 2. Then, turn-on the cook switch, make sure that you have properly inserted or placed the pan into the rice cooker with enough weight to depress the center thermostat, decrease in resistance should be observed since the cook heater will be activated. If this happen, the unit might be in good condition. For safety, place one probe across to the plug terminals and the other probe to the body, there should be very high (infinite) resistance. Proceed to checking for consistency of heat. If there's something different, refer to troubleshooting guide of this lesson. ACTIVITY 4.1 ------------ #### REASSEMBLING AND TESTING A RICE COOKER ##### Resources: ##### Directions: #### PERFORMANCE CHECK 4.1 REASSEMBLING AND TESTING A RICE COOKER ----------- -- -- -- -- -- -- -- **TOTAL** ----------- -- -- -- -- -- -- -- -- -- -- -- IV. SUMMATIVE ASSESSMENT ------------------------ I. **Directions:** Write the letter of the correct answer. Let the students answer the test on a separate sheet of paper. 1. A part of the rice cooker that prevents it from being turned on without the pan. A. Center Thermostat B. Thermal Fuse 2. A part of the rice cooker that opens the circuit when the temperature has gone unusually high. B. Center Thermostat B. Thermal Fuse 3. A part of the rice cooker that turns off the cooking cycle and starts the warming cycle. C. Center Thermostat B. Thermal Fuse 4. A system that compares the output with the expected result. D. Closed Loop System B. Open Loop System 5. A part of a control system used to monitor the output. E. Sensor B. Comparator 6. A test conducted to see the alignment and sufficiency of the heating plate on the pan. F. Bubbling Test B. Evaporation Test 7. A test conducted to see if the rice cookers will turn-of 1 minute or after the generation comes to a stop. G. Bubbling Test B. Evaporation Test 8. A kind of test to see if the heating element is in good condition. H. Bubbling Test B. Evaporation Test 9. A boiling point of water. I. 65˚C B. 134 ˚C 10. The metal and magnet will pop apart when this temperature is reached. J. 65˚C B. 134 ˚C II. **Directions.** Draw the schematic diagram of an electric rice cooker (without electronic control) and label each component 11-20 (10pts). -- -- -- -- III. **Directions:** Perform pre-testing and troubleshooting electric rice cooker in 30minutes. Initially, 10 points will be given if the appliance was repaired and point deduction will be applied following the criteria below: -- -- -- -- ##### Technical Terms -- -- -- --