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22

11 Measurements and Adjustments

Warning

• For continued protection against radiation hazard, replace

only with identical parts.

• When the 10 amp fuse is blown due to the operation of the

short switch, you must replace the primary latch switch and
short switch. Then follow the installation procedures below.

• Interlock switch replacement - In replacing faulty switches,

be sure mounting tabs are not bent, broken or otherwise
deficient in their ability to hold the switches.

• Refer to the schematic and wiring diagram to ensure proper

connection

11.1. Installation of primary latch

switch, secondary latch switch
and short switch.

1. When mounting the primary latch switch, secondary latch

switch and short switch to the door hook assembly. Fol-
low the instructions in figure 1.
NOTE: No specific adjustment during the insulation of
each switch into the door hook is necessary.

2. When mounting the door hook assembly to the oven

assembly, adjust the door hook assembly by moving it in
the direction of the arrow in figure 1. Ensuring the door
does not have any play in it. Check for play by pulling the
door assembly. 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 and second-

ary latch switches and check the continuity of the monitor
circuit and latch switches by following the component test
procedures on page.

11.2. Measurement of microwave

output

The output power of the magnetron can be determined by per-
forming the IEC standard test. However, due to the complexity
of the IEC test procedures, it is recommended to test the mag-
netron using the simple method outlined below.
Necessary equipment:

• 1 liter 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. Fill the beaker with exactly one liter of tap water. Stir the

water using the thermometer and record the beakers tem-
perature (Recorded as T1)

2. Place the beaker on the center of the glass cook plate.
3. Stir the water again and read the temperature of the bea-

ker (Recorded as T2)

4. The normal temperature rise at the high power position

for each model is shown in the table. (Figure 2)

Adjustment of latch switch assembly

Figure 1

TABLE (1L - 1min test)

RATED OUTPUT

TEMPERATURE RISE

1000W

8

°

C

Содержание NN-A750WB

Страница 1: ...W Grill 1360W Conv 1470w Combi 2770W Output IEC705 88 Micro 1000W Grill 1300W Conv 1400W Microwave Frequency 2450MHz Timer 99 Minutes 99 Seconds Oven Cavity Size 27L Outside Dimensions 510mm W x 477mm...

Страница 2: ...ges 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 Return the old unit fully repacked in the original shipping b...

Страница 3: ...3 3 Control Panels...

Страница 4: ...Set pad for 1 minute by pressing 1 min pad once 6 Press the start pad 7 When the first stage cooking has elapsed oven automatically switches to second stage 8 When second stage cooking has elapsed ove...

Страница 5: ...time pads to enter cooking time 5 Press start 1 Press combination pad 2 Press convection pad to select oven temperature 3 Select micro power 4 Press start if preheating 5 Set cooking time 6 Press sta...

Страница 6: ...6 4 12 Auto Weight Cook Programs 1 Select the desired auto weight cook program 2 Press to select grams or pounds and ounces 3 Enter the weight by pressing the up and down pads 4 Press Start...

Страница 7: ...7 5 Schematic Diagram 6 Wiring Diagram...

Страница 8: ...ines the power level and the cooking time and indicates the operating state in the display The table shows the corresponding cooking times for each category and its respective weight 2 When the cookin...

Страница 9: ...r 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 relay RY5 resultin...

Страница 10: ...w the selected tempera ture the digital programmer circuit operates power relay RY5 switching on the heater elements In the case of grill combination the sequence applies with the digital programmer c...

Страница 11: ...11 Grill and Microwave Duty Cycles Figure 2 Grill Convection And Microwave Duty Cycles...

Страница 12: ...12 Figure 3...

Страница 13: ...Inverter warning Figure 1 WARNING FOR INVERTER POWER SUPPLY U GROUND ING Check the high voltage inverter power supply circuit grounding This high voltage inverter power supply circuit board must have...

Страница 14: ...pair 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 electrical connect...

Страница 15: ...nector 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 8 Remove t...

Страница 16: ...30W sol dering iron carefully remove all solder from the terminal pins of the low voltage transformer and or power relays 2 With all of the terminal pins cleaned and separated from the DPC contacts r...

Страница 17: ...y is not mounted properly microwave power may leak from the clearance between the door and oven 3 Perform the microwave leakage test Disassembly of the door Figure 7 Adjusting the door hinge Figure 8...

Страница 18: ...18 One screw to remove the grill bracket Figure 11 Removing the grill element Figure 12...

Страница 19: ...ding the convection assem bly push upwards to remove 6 To remove the convection element remove the one screw E on the convection bracket A and 2 screws D on convec tion bracket B 7 Release the circula...

Страница 20: ...tor 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 with the door open and...

Страница 21: ...0 7 Temperature Sensor A temperature sensor is mounted on the oven cavity on the right hand side The resistance reading across the thermistor should read 300K ohm within a temperature range of 10 to 3...

Страница 22: ...e 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 and second ary la...

Страница 23: ...o do otherwise may result in a false reading or damage to your meter When dis connecting a plastic connector from a terminal you must hold the plastic connector and not the lead wire otherwise the lea...

Страница 24: ...24 Troubleshooting Fuse is blown Figure 2 Troubleshooting Other problems Figure 3...

Страница 25: ...25 Troubleshooting Inverter by Input out voltage Figure 4 Troubleshooting Inverter by Microwave Oven Input Current Figure 5...

Страница 26: ...26 13 Digital Programmer Circuit Troubleshooting Guide How to test the semiconductors...

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