John Lewis JLFSMWC003 Service Manual Download Page 1

HAD0901001C2

Microwave Oven

NN-CT878SBJQ
JLFSMWC003

32L OEM

United Kingdom

Summary of Contents for JLFSMWC003

Page 1: ...HAD0901001C2 Microwave Oven NN CT878SBJQ JLFSMWC003 32L OEM United Kingdom...

Page 2: ...oubleshooting 17 10 Part Replacement Procedure 20 11 Component Test Procedure 29 12 Measurements and Adjustments 31 13 Troubleshooting Guide 32 14 Digital Programmer Troubleshooting Guide 35 15 Descri...

Page 3: ...verter PCB as this can be very dangerous Replace the high voltage inverter circuit as a complete unit Return the old unit fully repacked in the original shipping box and completed paper work 4 Do not...

Page 4: ...am for up to 9 hrs 99 mins or used to time or for standing non cooking time 12 Clock Pad Refer to page 15 for setting the clock 13 lb oz Conversion Pad 14 More Less Pads 15 Stop Cancel Pad Before Cook...

Page 5: ...NN CT878SBJQ JLFSMWC003 32L OEM 5 5 Operation And Digital Programmer Circuit Test Procedure...

Page 6: ...NN CT878SBJQ JLFSMWC003 32L OEM 6...

Page 7: ...NN CT878SBJQ JLFSMWC003 32L OEM 7...

Page 8: ...NN CT878SBJQ JLFSMWC003 32L OEM 8 6 Schematic Diagram...

Page 9: ...NN CT878SBJQ JLFSMWC003 32L OEM 9 7 Wiring Diagram...

Page 10: ...ng 8 3 Auto weight defrost Auto weight Cook When an auto control feature is selected and the start pad pressed 1 The digital programmer circuit determines the power level and the cooking time and indi...

Page 11: ...supplying power to relay RY5 resulting in the convection heater turning off 3 When the temperature drops below the predetermined temperature the digital programmer circuit supplies power to power rel...

Page 12: ...program is completed When the oven temperature drops below the selected tempera ture the digital programmer circuit operates power relay RY5 switching on the heater elements In the case of grill comb...

Page 13: ...NN CT878SBJQ JLFSMWC003 32L OEM 13 8 5 1 convection and microwave duty cycles Figure 1...

Page 14: ...NN CT878SBJQ JLFSMWC003 32L OEM 14 8 5 2 grill and microwave duty cycles Figure 2...

Page 15: ...NN CT878SBJQ JLFSMWC003 32L OEM 15 Figure 3 8 5 3 Grill Convection and microwave duty cycles...

Page 16: ...he shaded columns in figure 1 indicate when the humid ity sensor heater is on 2 During the 30 second period there is no microwave activ ity When calculating the T2 time by using the formula below make...

Page 17: ...from danger in ordinary use extreme care should be taken during repair As you can see it looks like a TV flyback transformer however the current is extremely large and is therefore dangerous due to th...

Page 18: ...ver to discharge Please be sure to touch the chassis ground side first and then short to the output terminals WARNING There is high voltage present with high current capabilities in the circuits of th...

Page 19: ...pair 1 After repair or replacement of parts make sure that the screws of the oven etc are neither loose nor missing Microwaves might leak if screws are not properly tight ened 2 Make sure that all ele...

Page 20: ...ws holding the magnetron as shown in figure 2 NOTE After replacing the magnetron tighten the mount ing screws making sure that there is no gap between the waveguide and the magnetron to prevent microw...

Page 21: ...and support base from the oven 7 Remove the air guide E by un clipping the catch hooks 8 Remove the four screws holding the PCB to the inverter support base Caution when replacing the inverter power...

Page 22: ...on base with double faced adhesive tape Therefore apply ing hot air such as using a hair dryer is recommended for smoother removal 2 When installing a new escutcheon key board make sure that the surfa...

Page 23: ...nit 4 Remove the door key and spring from the door E After replacement of the defective component parts of the door reassemble it and follow the instructions below for proper installation and adjustme...

Page 24: ...gure 10 3 Disconnect the cables to the grill heater 4 Remove the grill cover by removing the 5 screws in figure 11 5 Remove the two screws holding the grill heater Figure12 6 Loosen the 2 screws holdi...

Page 25: ...NN CT878SBJQ JLFSMWC003 32L OEM 25 Removing the screws holding the grill heater Figure 11 Removing the grill element Figure 12...

Page 26: ...re 14 4 Remove the power cord 5 Remove the wire terminals from the circulation fan motor and the convection heater element 6 Remove the four screws from the oven base Figure 15 7 Carefully place the o...

Page 27: ...NN CT878SBJQ JLFSMWC003 32L OEM 27 Removing the oven back plate Figure 14 Removing the base plate Figure 15...

Page 28: ...NN CT878SBJQ JLFSMWC003 32L OEM 28 Removing the circulation motor Figure 16...

Page 29: ...hort Switch and Monitor Cir cuit 1 Unplug the lead wires from the HV inverter primary termi nals 2 Connect the test probes of the ohm meter to these leads 3 Test the continuity of the short switch wit...

Page 30: ...uld be replaced NOTE When measuring the resistance of the thermistor dis connect the connector from the digital programmer circuit NOTE If the microwave oven has been operated allow to cool to room te...

Page 31: ...Make sure that the latch keys move smoothly after adjustment is completed Completely tighten the screws holding the door hook assembly to the oven assembly 3 Reconnect the short switch primary switch...

Page 32: ...NN CT878SBJQ JLFSMWC003 32L OEM 32 13 Troubleshooting Guide...

Page 33: ...NN CT878SBJQ JLFSMWC003 32L OEM 33 Fuses are not blown Fuses are blown...

Page 34: ...NN CT878SBJQ JLFSMWC003 32L OEM 34 6A5BPQ Other problems Inverter circuit troubleshooting 6A5BPQ Alternative method for toubleshooting the inverter circuit...

Page 35: ...NN CT878SBJQ JLFSMWC003 32L OEM 35 14 Digital Programmer Troubleshooting Guide...

Page 36: ...NN CT878SBJQ JLFSMWC003 32L OEM 36...

Page 37: ...the display window has elapsed the oven turns off automatically via the control signal from the digital programmer circuit Note After auto cooking if the oven temperature is over the predetermined te...

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