R-7H55
19
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
(5) After approximately 16 seconds, microwave energy is produced, oven should turn off when water is
boiling (bubling).
If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation below.
TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT
To determine if the sensor is defective, the simplest method is to replace it with a new replacement
sensor.
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Remove the AH sensor.
(4) Install the new AH sensor.
(5) Re-install the outer case.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
6-1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
6-2. Place the container on the center of tray in the oven cavity.
6-3. Close the door.
6-4. Touch SENSOR REHEAT pad.
6-5. The oven will turn off automatically when the water is boiling (bubling).
If new sensor dose not operate properly, the problem is with the control unit.
CHECKING CONTROL UNIT
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Disconnect the wire leads from the cook relay.
(4) Disconnect the sensor connector that is mounted to lower portion of control panel.
(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:
6-1. Touch SENSOR REHEAT pad.
6-2. The control panel is in the sensor cooking operation.
6-3. After approximately 20 seconds, push plunger of select switch. This condition is same as
judgement by AH sensor.
6-4. After approximately 3 seconds, cooking operation turns off, an audible signal will sound,
and the display will then revert to the time of day.
If the above is not the case, the control unit is probably defective.
If the above is proper, the AH sensor is probably defective.
R1,R2 : 22
Ω
±
1% 1/2W
R3 : 10k
Ω
±
5% 1/4W
R4 : 1M
Ω
±
5% 1/4W
Sensor Dummy Resistor Circuit
Plunger
NC
NO
COM
COM
NO
NC
R3
R4
R1
R2
1
2
3
F-1
F-2
F-3
To connector (F)
on Control Unit.
CONNECTOR
Q
NOISE FILTER TEST
FUSE
M8A
L
N
RESISTOR 680K
LINE CROSS CAPACITOR 0.22µ /AC 250V
noise suppression coil
RESISTOR 10M
LINE BYPASS
CAPACITOR
0.0033µ /AC 250V
LINE BYPASS
CAPACITOR
0.0033µ /AC 250V
NOISE FILTER
WHT
RED
CARRY OUT 3D CHECKS
Disconnect the leads from the terminals of the noise filter. Using
an ohmmeter, check between the terminals as described in the
following table.
If incorrect readings are obtained, replace the noise filter unit.
MEASURING POINT
INDICATION OF OHMMETER
Between N and L
Approx. 680 k
Ω
Between terminal N and WHITE
Short circuit
Between terminal L and RED
Short circuit
CARRY OUT 4R CHECKS
