Sears 721.88502800 Manual page 45

High voltage components
Components Test
H.V.Diode (RECTIFIER) STEP 1. Test the diode to see if it is shorted.
Procedure:
1. Select the ohm scale on the meter.
2. Place the meter leads across the diode as pictured in
Figure 1. The reading should be "40MΩ," "OL," or a
reading of infinity.
3. Reverse the meter leads. The reading should again
indicate a reading of infinity. If the diode shows
"infinity" in BOTH directions, it is NOT shorted.
4. If the diode is not shorted, proceed to step 2.
STEP 2. Test the diode for forward biasing.
Procedure:
1. Select the DCV scale on the meter.
2. Using the meter, battery, and jumper wire, connect
the items as illustrated in Figure 2.
This has the positive side of the battery connected to
the cathode of the diode.
3. The diode should be forward biased therefore a
voltage reading of approximately 4.7 VDC to 6.4 VDC
will be read depending on meter, battery strength, etc.
(Note: If the meter leads were reversed, a negative
voltage of the same amount would be seen.)
STEP 3. Test the diode for reverse biasing.
Procedure:
1. Using the same scale on the meter, connect the
positive side of the battery to the anode of the diode
as illustrated in Figure 3.
2. The diode should be reverse biased therefore a
reading of 0 volt or a value displayed in mV will be
seen. (The display will be erratic changing
values rapidly in the mV scale.)
Figure 1 Figure 2
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Results Components
Magnetron
1. Remove wire leads. Install the magnetron seal
in the correct position.
ANTENNA
Check that the seal is in good condition.
2. Measure resistance. (ohm meter scale: Rx1)
GASKET
3. Measure resistance.
(ohm meter scale: Rx1000)
CHASSIS
FILAMENT
Normal:
Components
Approximately
4 .7-6.4V
Relay 2 1. Measure continuity.
2. Remove the lead wires and operate
Normal:
Approximately 0V
Fan Motor
1. Remove wire leads.
2. Measure resistance.
A
B
C
1. Remove lead wires.
Ventilation Motor
2. Measure resistance.
Turntable Motor
1. Remove wire leads.
2. Measure resistance.
Figure 3
Part No.: 3840W1T147B
High voltage components
Test Results
Normal: Less than 1 ohm
Filament terminal
Abnormal: Infinite
Filament to chassis
Normal: Infinite
Other component tests
Test Results
Power
Open
(ohm meter scale: Rx1)
Level
1 4 Sec
oven at power level 1 through power
2 6 Sec
level 10.
3 8 Sec
4 10 Sec
5 12 Sec
6 14 Sec
7 16 Sec
8 18 Sec
9 20 Sec
10 22 Sec
Normal: Approximately
Terminal Ⓐ-Ⓒ : 35 to 50 ohms
Terminal Ⓐ-Ⓑ : 5 to 15 ohms
(ohm meter scale: Rx1)
Abnormal:
Infinite or several.
Normal:
Approximately
(ohm meter scale:Rx1)
20 to 40 ohms
Abnormal:Infinite
Normal:
Approximately
(ohm meter scale: Rx1000) 2.0 to 3.0 Kohms
Abnormal:
Infinite or several.
Part No.: 3840W1T147B
10-5
Components Test
Absolute Humidity
1. Disconnect sensor connector from
Sensor
micom computer board.
(For sensor model)
2. Measure resistance terminal to
terminal (ohm meter scale: R X 1000)
BK
1
RD
2
3 WH
Stirrer Motor
1. Remove lead wires.
2. Measure resistance.
(ohm meter scale:Rx1000)
Close
18 Sec
16 Sec
14 Sec
12 Sec
10 Sec
Parts layout
8 Sec
6 Sec
4 Sec
OVEN
2 Sec
THERMOSTAT
STIRRER
(6930W1A003J)
ABSOLUTE
0 Sec
MOTOR
HUMIDITY SENSOR
(6549W1S002G)
(6501W1A013A)
OVEN LAMP
(6912A40002E)
(3B74133K)
(6201W2A018L)
T/TABLE MOTOR
(6549W1S018C)
COOKTOP LAMP
(6912A40002E)
PRIMARY SWITCH
(6600W1K004C)
SECONDARY
SWITCH
(6600W1K004C)
These are main parts Number.
Refer to the SVC manual about detailed parts No.
Parts No. can be changed after reporting PCR.
(changed part no. will have the same performance)
Results
Normal:
Approximately
BK-RD: 6.0 Kohms
RD-WH: 3.0 Kohms
BK-WH: 3.0 Kohms
Abnormal:
Infinite or approx. 0 ohm
Normal:
Approximately
120 to 135 ohms
Abnormal:Infinite
VENT MOTOR
(6549W1V006J)
CAPACITOR
(0CZZW1M001C)
FAN MOTOR
(6549W1F009H)
MAGNETRON
(6324W1A001E)
H.V. CAPACITOR
(0CZZW1H004C)
H.V. DIODE
(RECTIFIER)
(6021W3B001Q)
H.V. TRANSFORMER
(6170W1D100C)
MGT THERMOSTAT
(6930W1A003K)
MONITOR
SWITCH
(6600W1K004B)
Part No.: 3840W1T147B
10-6