Related Manuals for Sharp R-22JT
Summary of Contents for Sharp R-22JT
- Page 1 Sharp Electronics Corporation Servicing Commercial Microwave Ovens R21JC/21HT & R22GTF/R22JT...
- Page 2 Len Hahn Senior Manager, Field Services & Support These ovens should not be adjusted or repaired by anyone except properly qualified service personnel.
- Page 3 Objective This course has been designed around the R22JT Commercial Microwave Oven. All disassembly and testing procedures refer to the R22JT only. While most heavy duty ovens are quite similar please refer to the specific model you are working on. Your have information on all four models, R21 series and R22 series.
- Page 4 Microwave Technologies Quiz 1. What is Microwave energy? a. Energy created by nuclear radiation. b. Energy created by chemical reaction. c. Energy created by electromagnetic generation d. Energy created by atomic fusion 2. What is the frequency at which the magnetron operates? a.
- Page 5 Microwave Technologies Quiz Microwave energy cooks food from a. from the outside to the inside b. from the inside to the outside. c. only from the top. d. only from the bottom. 4. Why does food sometimes appear to cool faster when cooked in a microwave than when cooked in a conventional oven? a.
- Page 6 Microwave Technologies Quiz 5. When the microwave recipe calls for a "let stand" time, what is this allowing for? a. The microwave to escape from the food. b. Allows the food to cool before eating. c. Allows the cooking container to cool before handling. d.
- Page 7 Microwave Technologies Quiz 7. When working on a microwave oven with the cabinet removed, the technician is exposed to a lethal danger. What is the danger? a. The high voltage and current potentials even when power is removed. b. Radiation energy. c.
- Page 8 Microwave Technologies Quiz 9. How often must a microwave oven be tested for leakage? a. Anytime after service. b. Only if the customer complains of headaches. c. Only if the door or door switches are repaired. d. Only if the magnetron is replaced. 10.
- Page 9 R-21JCA Control Panel 1000 Watts...
- Page 10 R-21JCA Oven diagram Air ventilation cover and openings Air intake openings Ceramic shelf Rotary antenna...
- Page 11 R-21JCA Ceramic Shelf Removal Using a putty knife, lift up from underneath the ceramic shelf to remove shelf from cavity. Be careful not to damage the rubber fins. Rubber fins No rubber fin...
- Page 12 R-21JCA Ceramic Shelf Installation Position the front of the shelf with the front of the oven. The front edge of the shelf does not have a rubber fin. Push down on the rear of the shelf to complete the Rubber fins installation taking care not to damage the rubber fins.
- Page 13 R-21JCA Schematic...
- Page 14 Transformers •Transformers can be used to step-up or Primary step-down an applied AC voltage •The High Voltage transformers that are used in microwave ovens are the step up type Input= •The 22JT employs two 1:20 step up 120 volts transformer which outputs 20 volts for every volt applied to the primary Secondary •When we apply 120 volts to the HV...
- Page 15 Transformers •Secondary current is inversely proportional to the turns ratio Primary •Available output current in our 1:20 step up transformer will be 20x less than the current on the primary •The high voltage doubler circuit will Input= double the transformer secondary 8 amps voltage to 4800 volts with an output current between 300ma and 450ma...
- Page 16 Danger...
- Page 17 Electrocution...
- Page 18 R-21JCA Single Magnetron...
- Page 19 High Voltage Doubler Operation...
- Page 20 High Voltage Doubler Operation Doubler charging Doubler Discharging “Voltage Adding”...
- Page 21 Magnetron Operation ¼ wave antenna Anode Resonant Cavity Cathode & Heater Magnet around resonant cavity not shown...
- Page 22 Interior of Magnetron...
- Page 23 R21JCA Trouble shooting tips 1. Magnetron temp fuse open = Check magnetron venting and timer operation. This unit is susceptible to get set to run without food load. 2. Oven temp fuse open = Check for proper venting for oven. 3.
- Page 24 R-21JCA Schematic...
- Page 25 R-22JT Schematic 1200 Watts...
- Page 26 R22/25JT Disassembly Procedures Units can be stacked for some restaurant applications. In this case, the units need to be separated by fixing angle removing the before servicing.
- Page 27 CRITICAL SAFTEY WARNING WARNING! You can be seriously INJURED or KILLED from the High Voltage circuit inside the Microwave Oven Disconnect AC Power and discharge the HV circuit before servicing...
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Page 28: Outer Case Cabinet Removal
Outer Case Cabinet Removal Disconnect AC power before Cabinet removal; this will give the HV Doubler Circuit time to Discharge... - Page 29 Outer Case Cabinet Removal Remove 2 screws on each side Remove 7 screws, which are placed around the perimeter of the cabinet...
- Page 30 Outer Case Cabinet Removal Tilt the cabinet upwards to release, and lift away You now have access to the HV circuit and control unit...
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Page 31: Warning, High Voltage
WARNING, HIGH VOLTAGE Using a screwdriver with an insulated handle; short together the two terminals of each High Voltage Capacitor H.V. Capacitors Short terminals with screwdriver... -
Page 32: Rear Cabinet Removal
Rear Cabinet Removal Remove 8 screws Machine thread Note: These 2 screws are brass Lift up the rear cabinet; be careful not to break the AC Line connectors... - Page 33 Rear Cabinet Removal You can gently lay down the rear cabinet on top of the unit You can disconnect the 2 AC Line connectors and remove the 1 grounding screw to completely remove the rear cabinet...
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Page 34: Rear View
Rear View Upper Magnetron (1) White connector Lower Magnetron (2) Blue connector Rear View... -
Page 35: Right Side View
Right Side View H.V. Capacitor for Upper Magnetron High Noise Filter Voltage Rectifier Ass’y for Upper Magnetron Blower Motor Power Transformer for Upper Magnetron (Note: White Connectors on Harness) - Page 36 No Case positive lock connectors...
- Page 37 Right Side View H.V. Capacitor for Lower Magnetron Latch High Hook Ass’y Voltage Rectifier Ass’y for Lower Control Magnetron Unit Power Transformer for Lower Magnetron (Note: Blue Connectors on Harness)
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Page 38: Control Panel Removal
Control Panel Removal Remove the air intake filter Ass’y Gently pull the locks straight out to remove filter... - Page 39 Control Panel Removal Remove 2 screws Slide control panel down to release...
- Page 40 Control Panel Removal Mark down the position of all connectors on a piece of paper, and remove all 9 connectors. Be sure to connect the cables in their exact original positions on the new control board...
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Page 41: Control Panel Disassembly
Control Panel Disassembly Key Unit Control Unit Remove 5 screws Front View Rear View... - Page 42 Control Panel Disassembly Lift up on the lock of cable connector; CN-G to release the lock Gently pull up on the Key unit cable...
- Page 43 Control Panel Disassembly Control Panel Control Unit Frame with Key Unit...
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Page 44: Door Removal
Door Removal Remove 4 screws, 2 screws per hinge These screws can be very tight; you may need a pliers or wrench to loosen before using a screwdriver... - Page 45 Door Removal Open door and carefully pull door straight out Door removed from unit...
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Page 46: Door Installation
Door Installation Install door and tighten screws on the upper and lower hinges Apply Gorilla glue and test for normal latch hook operation and leakage before glue dries, adjust door if necessary... -
Page 47: Door Disassembly
Door Disassembly... - Page 48 Lower Stirrer Motor Access •Snip off •Bend sharp edges with pliers •Replace cover with screw...
- Page 49 R25JT Schematic 2100 Watts Voltage Switches...
- Page 50 R25JT Voltage Switches EE4 EE5 The R25JT utilizes Voltage Switches to select the input voltage between 208 and 230 volts, since power sources vary. Note: The oven will display an EE4 or EE5 if the voltage switch is set incorrectly. Always measure the line voltage before adjusting the voltage switch.
- Page 51 How to set Voltage Switches...
- Page 52 Latch Hook Ass’y Monitor Switches; each high voltage • circuit has its own monitor switch, which is used to detect a door Monitor switch 2 latching failure. The monitor Monitor switch 1 switches will shunt across the AC line and open the main fuse if activated, disabling the unit.
- Page 53 Latch Hook Ass’y Secondary interlock Switches; each • high voltage circuit has its own secondary interlock switch, which is used to supply AC line voltage to each Secondary high voltage circuit. The secondary interlock switch 2 interlock switches close when the Secondary door is shut.
- Page 54 Latch Hook Ass’y The door sensing Switch; senses if the • door is open or closed. In addition, it is also used in the standby mode. • Standby mode; operates the blower motor to cool the magnetrons when the door is opened.
- Page 55 Control Panel Schematic Foil pattern Primary interlock relay 1 Primary interlock relay 2 Door switch Oven Magnetron Key unit thermistor thermistor...
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Page 56: Control Panel
Control Panel • Primary interlock relays, 1 & 2; apply AC line voltage to each power transformer which supplies the doubler circuits with 2400 volts for magnetron operation. - Page 57 Control Panel Exhaust duct Oven thermistor; is located on the exhaust duct and is used to measure the exhaust air temperature. Oven thermistor...
- Page 58 Control Panel Magnetron thermistor Magnetron thermistor; is used to measure the air temperature around the upper magnetron, which can cause the unit to shut down. This also protects the lower magnetron from overheating...
- Page 59 Control Panel The key unit is a matrix of switches that is used for selecting the cooking process...
- Page 60 Control Panel Foil patterns The very fine foil patterns acts as a fuse and will open under excessive current draw...
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Page 61: Troubleshooting
Troubleshooting THE UNIT MUST REMAIN DISCONNECTED FROM AC POWER AT ALL TIMES UNLESS SPECIFIED Disconnect the primary coils of each power transformer and leave disconnected until all troubleshooting activities have been completed... - Page 62 Troubleshooting the Noise Filter • The noise filter is employed to meet FCC regulations by not allowing the 2450Mhz RF energy to travel out of the unit via the AC power lines. • A faulty noise filter will cause a no power condition.
- Page 63 Troubleshooting the Noise Filter Disconnect wires from noise filter before proceeding...
- Page 64 Troubleshooting the Noise Filter...
- Page 65 Troubleshooting the Noise Filter...
- Page 66 Troubleshooting Control Panel “Dead” Disconnect all wire harnesses except the AC input connector Key unit CN-4 and the door sensing switch connector CN-B. (the door CN-B sensing switch will not effect a dead unit) Disconnect the Key unit connector CN-G CN-4...
- Page 67 Troubleshooting Control Panel “Dead” Measure 120 volts at pins 1 & 7 of CN4 If 120 volts is present, proceed with foil pattern check Pin 7 If 120 volts is not available, check the noise filter / fuse, and check the oven temperature Pin 1 fuse if required...
- Page 68 Troubleshooting Control Panel “Open Foil Pattern” Visually inspect varistor and check for burns...
- Page 69 Troubleshooting Control Panel “Open Foil Pattern” Using a VOM, measure the coil resistance of the primary winding of the transformer Check for 270Ω±10%...
- Page 70 Troubleshooting Control Panel “Open Foil Pattern” Check for open foil patterns points “a” and “b” on the PWB J1 d Foil Repair Procedure...
- Page 71 Troubleshooting Key Unit Key unit Disconnect all wire harnesses except the AC input connector CN-4 and the door sensing switch connector CN-B. Disconnect the Key unit connector CN-G...
- Page 72 Troubleshooting Key Unit Connect AC power cord to wall outlet and open the oven door The blower and oven light will turn on indicating that the control panel is OK, however, the key unit must be shorted...
- Page 73 Troubleshooting Key Unit Momentarily shunt across pins 7&10 of the key unit connector CN-G If a beep is heard the key unit is defective If the control panel does not beep, the control panel is defective DISCONNECT AC POWER CORD FROM WALL OUTLET!
- Page 74 Troubleshooting Door Switch Door switch Confirm the latch hook is Note: orange wire activating the plunger of the door switch when the door is open Using a VOM, measure across the door switch contacts and check for continuity when the door is closed Open the door and now check for an open circuit...
- Page 75 Troubleshooting the Primary Interlock Relays CN-G Disconnect all wire harnesses except the AC input connector CN-4, door CN-B sensing switch connector CN-B and Key unit CN-G CN-4...
- Page 76 Troubleshooting the Primary Interlock Relays Connect AC power cord to wall outlet Start cook process and measure for continuity across primary Relay 1 interlock relays 1 and 2 Relay 2 Note: “EE3” will appear on display after 9 seconds DISCONNECT AC POWER CORD FROM WALL OUTLET!
- Page 77 R-21JCA Control Panel RY-2 Power transformer RY-1 Oven lamp, stir motor, fan motor...
- Page 78 R-21JCA “Open Foil Pattern” Check for open patterns points “a” and “b” on the Foil Repair Procedure...
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Page 79: Troubleshooting Using Fault Codes
Troubleshooting Using Fault Codes Please refer to the following fault code tables in the respective Service Manuals to further troubleshoot each model: R22JT Page 11 R25JT Page 12 R21JCA Does not use fault codes... - Page 80 R22JTF Error code reference...
- Page 81 R22JTF Error code...
- Page 82 R25JTF Error codes...
- Page 83 Magnetron Thermistor “EE16” “EE17” There is only 1 magnetron thermistor, which is located on the upper magnetron If “EE16” is displayed on the control panel, the magnetron thermistor is “open” If “EE17” is displayed, the magnetron temperature is too high...
- Page 84 Magnetron Thermistor “EE16” “EE17” To check the magnetron thermistor, disconnect the thermistor and measure with a VOM See chart below for normal resistance meter readings Magnetron thermistor connector...
- Page 85 Oven Thermistor “EE6, “EE7” Exhaust duct If “EE6” is displayed on the control panel, the oven thermistor has failed If “EE7” is displayed, the exhaust air temperature In this case is too high. you would need to check the filter, and be sure that the units air rear vents are not blocked.
- Page 86 Oven Thermistor “EE6, “EE7” Exhaust duct To check the oven thermistor, disconnect the thermistor and measure with a VOM See chart below for normal resistance meter readings Oven thermistor...
- Page 87 Dual Magnetron Operation 120V Hot output of noise filter, via primary interlock relays 1 & 2 Common output of noise filter Power transformers are wired 180º out of phase...
- Page 88 High Voltage Doubler Operation While the upper high voltage circuit is supplying power the magnetron, the lower high voltage circuit is charging.
- Page 89 Troubleshooting the Magnetron “EE1” EE2” “EE3” A failure of any high voltage component including the primary interlock relays on the control panel, latch hook ass’y, and secondary interlock switches can cause the following error codes. These error codes usually display within 9 to 13 seconds from when the cook cycle has started: EE1: magnetron 1 failure...
- Page 90 Troubleshooting EE1 and EE2 Troubleshooting techniques for fault codes EE1 and EE2 are common for each.
- Page 91 Troubleshooting EE1 and EE2 1. To troubleshoot EE1 or EE2, make sure that you are checking the correct section relating to magnetron circuits and control section. Note: EE1, EE2, or EE3 usually does not necessarily indicate a defective magnetron, so save yourself time and money by checking the associated parts as indicated in the following slides.
- Page 92 Troubleshooting EE1 and EE2 2. Remove primary wires from H.V. transformer and measure for 120v AC. If 120 volts or AC line input voltage is measured at the primary, would indicate that the problem would be strictly a H.V. or magnetron issue. The control circuits would be operating normally with AC voltage present.
- Page 93 Troubleshooting EE1 and EE2 If 120 volts or AC line input voltage is not measured at the primary, the problem would be the control circuits; which includes the control panel, secondary interlock switches and latch hook ass’y.
- Page 94 Troubleshooting EE1 and EE2 4. Check the latch hook and secondary interlock switches. As you can see, this unit has a defective latch hook ass’y since only one secondary interlock switch is activated. Note: Verify that the wires and connectors are tight and Defective latch hook ass’y not burned.
- Page 95 Troubleshooting EE1 and EE2 5. If the latch hook appears to be functioning normally, check for continuity across the switches. 6. Measure for continuity across each switch with the oven door closed. This can be accomplished in circuit with unit unplugged from AC power.
- Page 96 Troubleshooting EE1 and EE2 7. Check the primary interlock relays. Connect AC power cord to wall outlet Start cook process and measure Relay 1 for continuity across primary interlock relays 1 and 2 Relay 2 Note: “EE3” will appear on display after 9 seconds Replace control PWB if there is no continuity at any of the 2...
- Page 97 Troubleshooting EE1 and EE2 At this point you probably have repaired the faults by replacing control parts. 8. If you found voltage at the primary of the H.V. transformer, then the problem is most likely to be a defective H.V. circuit or defective magnetron. Please follow the next few slides on how to troubleshoot the H.V.
- Page 98 Troubleshooting the Power Transformers Disconnect primary winding and measure less then 1 Ω with an ohm meter...
- Page 99 Troubleshooting the Power Transformers Disconnect secondary winding and measure approximately 106Ω...
- Page 100 Troubleshooting the Power Transformers Disconnect filament winding between H.V capacitor and magnetron measure less than 1Ω...
- Page 101 Troubleshooting the H.V. Doubler Diode Remove grounding screw and check rectifier With meter set at X1000 you should get a high resistance in one direction (forward bias)
- Page 102 Troubleshooting the H.V. Doubler Diode Reverse the leads of the ohm meter and you should read infinity (reverse bias) Note: Loose H.V. lugs wires can cause intermittent or no high voltage...
- Page 105 Troubleshooting the H.V. Doubler Capacitor Remove one lead from the Capacitor and put the meter leads onto the capacitor terminals. You will see a momentary resistance reading and the meter will go back to infinity. Reverse the leads and you will see the same.
- Page 106 Troubleshooting the Magnetron Remove the leads from the magnetron and read the filament resistance. It should be less than one Ohm.
- Page 107 Troubleshooting the Magnetron Check to ensure you do not have a cathode to anode short. You should read infinity between the terminals and the case of the magnetron.
- Page 108 Microwave Output Power Test...
- Page 109 Sharp Electronics Corporation This concludes our commercial microwave training...