Inverter NN-T591WB Service Manual

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MOP01060022C2

Microwave Oven

NN-T591WB

NN-T571SB

NN-T551WB

NN-T551CB

27L

United Kingdom

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Summary of Contents for Inverter NN-T591WB

Page 1 MOP01060022C2 Microwave Oven NN-T591WB NN-T571SB NN-T551WB NN-T551CB United Kingdom...
Page 2 1. Inverter Warning The inverter board looks like a normal printed circuit board. However, this printed circuit board supplies the magnetron tube with very high voltage and current. The inverter PCB: 1. Produces very high voltage and current. 2. Has an Aluminium heat sink which becomes very hot.
Page 3 3. Do not attempt to repair the inverter PCB as this can be very dangerous. Replace the high voltage, inverter circuit as a complete unit. 4. Do not adjust or tamper with the pre-set volume on the inverter board. It is very dangerous to adjust this pre-set without proper test equipment.
Page 4 Inverter Layout 2. FEATURE CHART Function NN-T551WB NN-T591WBNN- NN-T551CB T571SB Microwave Sensor reheat Sensor Cook Turbo reheat Weight reheat Weight cook Weight combination Weight defrost Delay/Stand More / Less Kg - lb/oz Stage cooking Clock Word prompt English English 3. Control Panels...
Page 5 4. Operation And Digital Programmer Test Procedure 4.1. Setting The Clock 1. Plug the power supply cord into the wall outlet 2. Press the clock pad 3. Enter the time of the day...
Page 6 4. Press the clock pad 4.2. Microwave Cooking 1. Place a water load in the oven 2. Press Micro power once to set high power 3. Set time at 10 sec. by pressing 10 sec. pad once 4. Press Micro power pad 3 times to set medium power 5.
Page 7 7. When the first stage cooking has elapsed oven automatically switches to second stage 8. When second stage cooking has elapsed oven bleeps 5 times and shuts off 4.3. Turbo Reheat 1. Place water load in the oven 2. Press the Turbo reheat button once 3.
Page 8 3. Enter the weight by pressing the Up & Down or more less pads. 4. Press Start 4.5. Delay Stand 1. Set power level and time 2. Press Stand 3. Set standing time 4. Press Start 4.6. Delay Start...
Page 9 1. Press delay 2. Set delay time 3. Set power level and time 4. Press start pad 4.7. Auto Weight Cook Programs NN-T551 1. Select the desired auto weight cook program 2. Press to select grams or pounds and ounces 3.
Page 10 6. Description Of The Operating Sequence 6.1. Variable power cooking control The output power is controlled by the inverter power supply, which is controlled by signals from the digital programmer circuit (DPC). The digital programmer cicruit operates relay RY1 to supply power to the inverter circuit. The outpower is controlled...
Page 13 Variable power cooking Setting Output On Time Off Time Turbo 1000W High 900W Defrost 440W Medium 600W 440W Simmer 440W Warm 440W NOTE 1. The ON/OFF time ratio does not corespond with the percentage of microwave power since approximately 2 seconds are required to heat the magnetron filament.
Page 14 6.3. One touch Auto sensor cooking NN-T591 NN-T571 Auto sensor cook is a revolutionary way to cook by microwave without setting a power level or selecting a time. All that is necessary is to select an auto sensor program before starting to cook. Understanding Auto sensor cooking.
Page 15 Catergory K FACTOR POWER POWER STANDARD fresh HIGH HIGH vegetables frozen HIGH HIGH vegetables Figure 1 Auto sensor cooking 7. Cautions to Be Observed When Troubleshooting Unlike many other appliances, the microwave oven is a high voltage, high current device. Though it is free from danger in ordinary use, extreme care should be taken during repair.
Page 16 WARNING FOR INVERTER POWER SUPPLY (U) GROUNDING Check the high voltage inverter power supply circuit grounding. The high voltage inverter power supply circuit board must have a proper chassis ground, the inverter grounding bracket must be connected to the chassis. If the inverter board is not...
Page 17 DANGER! Be sure that the inverter circuit is properly grounded via the inverter earth bracket. Figure 2 Grounding of the inverter circuit board WARNING! DISCHARGE THE HIGH VOLATGE CAPACITORS For about 30 seconds after the oven is turned off, an electric charge remains in the high voltage capacitors in the inverter power supply circuit board.
Page 18 There is high voltage present with high current capabilities in the circuits of the primary and secondary windings, choke coil and heat sink of the inverter. It is extremely dangerous to work on or near these circuits with the oven energized. DO NOT measure the voltage in the high voltage circuit including the filament voltage of the magnetron.
Page 19 The following components have potentials above 250V while is appliance is operated. Magnetron High voltage transformer (Located on inverter (U)) High voltage diodes (Located on inverter (U)) High voltage capacitors (Located on inverter (U)) Pay special attention in these areas.
Page 20 When replacing the magnetron, ensure that the antenna gasket is in place. Note The magnetron used for this model is unique for the inverter power supply system. Make sure to use the one as listed in the parts list. Figure 1...
Page 21 4. Remove the one screw holding the earth wire to the magnetron. 5. Remove the connector CN701 and CN702 from the inverter PCB. 6. Remove the two screws holding the inverter base to the chassis (See figure 2). 7. Carefully remove the inverter PCB and support base from the oven.
Page 22 4. Make sure that the heat sink has enough space (gap) from the oven. Take care not to touch any lead wire to the aluminium heat sink because it is hot. Figure 2 Removal of the inverter PCB. Figure 3...
Page 23 Disconnecting the PCB lock connector. 8.3. Digital Programmer Circuit (DPC) and membrane key board. NOTE: Ground any static electric built up on your body before handling the DPC. 1. Disconnect all connectors from the DPC. 2. Remove the two screws holding the escutcheon base and slide the escutcheon base upward slightly.
Page 24 Removal of DPC AU and DPC DU Figure 6...
Page 25 Grounding of the stainless facia 8.4. Low voltage transformer and/or power relays (RY1) Note Be sure to ground your body to discharge any static before handling the DPC. 1. Using a solder wick or a de-soldering tool and a 30W soldering iron, carefully remove all solder from the terminal pins of the low voltage transformer and/or power relays.
Page 26 2. With all of the terminal pins cleaned and separated from the DPC contacts, remove the defective transformer/power relays and install the new components making sure that the terminal pins are inserted completely. Carefully re solder all terminal contacts carefully. Note Do not use a soldering iron or de soldering tool of more than 30 watts on DPC contacts...
Page 27 Removing the fan motor. 8.6. Door disassembly 1. Remove door C from door E by carefully pulling outward starting from the upper right hand corner using a flat blade screwdriver. 2. Remove four screws holding the door E to the door A assembly. 3.
Page 28 2. Adjust so that the door has no play between the inner door surface and the oven front surface. If the door assembly is not mounted properly, microwave power may leak from the clearance between the door and oven. 3. Perform the microwave leakage test. Figure 7 Disassembly of the door.
Page 29 Adjusting the door hinge. 8.7. Turntable Motor 1. Remove the motor cover by breaking off at the 8 spots indicated by the arrows. 2. Disconnect the two lead wires connected to the turntable motor. 3. Remove the turntable motor by removing the two screws. Note: After breaking off the motor cover, make sure that cut-off portions are properly trimmed off or bent inside so that no sharp edges are exposed.
Page 30 Removing the turntable motor cover. Figure 10...
Page 31 Removing the two scews fixing the turntable motor. 8.8. Steam Sensor NN-T591 NN-T571 1. Remove 1 screw holding the steam sensor unit 2. Disconnect CN7 connector for the digital programmer circuit board. 3. Remove the exhaust guide from the steam sensor unit. 4.
Page 32 Removing the steam sensor...
Page 33 Fitting the new sensor 9. Component Test Procedure Caution 1. High voltage is present at the high voltage terminal of the inverter unit, including the aluminium heat sink. 2. It is not necessary or advisable to attempt to measure this high voltage.
Page 34 (Close) 9.2. Short Switch and Monitor Circuit 1. Unplug the lead wires from the HV inverter primary terminals. 2. Connect the test probes of the ohm meter to these leads. 3. Test the continuity of the short switch with the door open and the door closed using the lowest ohm scale.
Page 35 Check the continuity between the switch terminals, by tapping an appropriate pad on the keyboard. The keypad matrix is shown on P.28. 9.5. Inverter Power Supply Caution DO NOT try to repair this inverter power supply). Replace as a whole H.V. Inverter Unit. Inverter Power Supply Diagram...
Page 36 9.6. Inverter Power Supply Unit Warning Do not attempt to make any measurements in the high voltage circuitry of the inverter or magnetron. See troubleshooting of the inverter circuit and magnetron on P.19 to determine if the inverter power supply is still functioning.
Page 37 5. T1 cooking switches the cooking time T2. 6. The cooking time T2 appears in the display window. If the following times appear the steam sensor is functioning normally. T1 TIME T2 TIME 1 MIN 30 SEC - 4 MIN 8 SEC - 23 SEC 10.
Page 38 recommended to test the magnetron using the simple method outlined below. Necessary equipment: 1 litre beaker. Glass thermometer. Wrist watch or stop watch. NOTE: Check the line voltage under load. Low voltage will lower the magnetron output. Take the temperature readings and heating time as accurate as possible. 1.
Page 39 11. Troubleshooting guide Caution 1. Do not try to repair this H.V. Inverter power supply. Replace as a whole unit. When returning the inverter unit pack in the original inverter box. 2. Do not adjust the preset volume on the H.V. Inverter. It is very dangerous to repair...
Page 40 5. Discharge the high voltage capacitors on the inverter. 6. When checking the continuity of the components on the H.V. inverter circuit, disconnect one lead wire from these parts and then check the continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
Page 46 Troubleshooting Inverter by Microwave Oven Input Current 12. Digital Programmer Circuit Troubleshooting Guide Figure 2 How to test the semiconductors 13. Main Parts List 1. Part numbers are indicated on most mechanical parts. Please use these part numbers for part orders. Do not use the description of the part.
Page 49 Remarks E30014N30HBP DOOR A NN-T591WB NN-T551WB E30014N30BP DOOR A NN-T551CB E302A4N20SBP DOOR A ASSEMBLY NN-T571SB E31464N00BP DOOR SCREEN B NN-T591WB NN-T551WB NN-551CB E302K4N00BP DOOR E ASSEMBLY E30214000AP DOOR KEY SPRING E30184L00GS DOOR KEY E30854N30BP DOOR C E30064N30BP UPPER HINGE E31454N00BP...
Page 52 SPRING E80344L10HBP ESCUTCHEON BASE NN-T591WB NN-T551WB E80344L10BP ESCUTCHEON BASE NN-T551CB E800S5D30SBP ESCUTCHEON BASE ASSY NN-T571SB E81274L10BP ESCUTCHEON BACK PLATE NN-T591WB NN-T551WB NN-T551CB E81274V00SBP ESCUTCHEON BACK PLATE NN-T571SB E603L5D30BP DPC AU NN-T591WB NN-T571SB E603L5D20BP DPC AU NN-T551WB NN-T551CB E66164L00GS RIBBON CABLE...
Page 55 18. Trim Kit Accessories Trim kit. No. Ref 1 Ref 2 Remarks Top And Bottom Trim Side Trim NN-TKV69W E1603A510HBP E1601A510HBP NN-T591WB NN-T551WB NN-TKV69C E1603A510BP E1601A510BP NN-T551CB Trim kit assemmbly Instruction E0003A4N30BP 19. Key Board Matrix 20. Digital programmer Circuit DPC Schematic 1 DPC Schematic 2 21.
Page 60 21.1. E603L5D30BP DPC AU Remarks Ref. No. Part No. Part Name & Description R180 ERDS2TJ361T 360R Carbon Resistor D40,D41 AESS133T-77 Diode D180-D182 AESQTLGE260T Green LED CX320 EF0EC8004T4 Ceramic Resonator SW40-SW50 EVQ11L05R Push Switch SW53-SW63 C110 C20 C40- AECU1F103Z50 10nF Chip Capacitor C220 C221 AECU1F104Z25 100nF Chip Capacitor...
Page 61 4 Pin Connector RY2 RY3 AEBGG5N1A12 12 V Relay AEGG5G1A12 12 V Relay AEEM19FEBVKN 19 Pin Connector AEEMXD05507W 7 Pin Connector E03525D00BP 3-Wire Inverter Connection IC480 AEHMH705S Hybrid IC IC25 AEICP25011HL Photocoupler IC AESTS1WBA60B Diode Bridge (600V) ECA2WHG220E 22uF 450V Electrolytic Capacitor...
Page 62 Remarks Ref. No. Part No. Part Name & Description R180 ERDS2TJ361T 360R Carbon Resistor D40,D41 AESS133T-77 Diode D180-D182 AESQTLGE260T Green LED CX320 EF0EC8004T4 Ceramic Resonator SW41-SW44 EVQ11L05R Push Switch SW46-SW63 C110 C20 C40- AECU1F103Z50 10nF Chip Capacitor C220 C221 AECU1F104Z25 100nF Chip Capacitor C222 C224 C22 R111-113 R20...
Page 63 Ref. No. Part No. Part Name & Description Remarks E03525D00BP 3-Wire Inverter Connection IC25 AEICP25011HL Photocoupler IC AESTS1WBA60B Diode Bridge (600V) ECA2WHG220E 22uF 450V Electrolytic Capacitor BZ310 EFBAH20C001 2KHz Buzzer ERZV10D511CS Varistor 510V IC10 ETXMJ197X1BG Switching Power Supply...

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Nn-t571sb Nn-t551wb Nn-t551cb