19
R-1750
R-1751
R-1752
R-1754
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
4. Transistor Q2 and Q3
Check the resistance of transistor Q2 and
Q3 by using ohmmeter as shown in Fig-
ure B-5.
The resistance between B and E of tran-
sistor Q2 and Q3 is approx. 20
Ω
The resistance between C and E is over
range.
If incorrect resistance appear, replace it.
NOTE: When a digital ohmmeter is used,
reverse the connection of ohm-
meter leads against Figure B-5.
Figure B-5. Check for transistor Q2 and Q3.
After check of inverter unit;
CAUTION: DO NOT OPERATE INVERTER UNIT BY ITSELF.
1. Install the inverter unit to the microwave oven securely.
2. Reconnect all leads removed from components during testing.
3. Reinstall the outer case (cabinet).
4. Reconnect the power supply cord after the outer case is installed.
CAUTION: DO NOT CONNECT THE OVEN TO WALL OUTLET WITHOUT THE OUTER
CASE INSTALLED.
5. Measure the microwave output power at full power cooking operation (refer to Test Procedure of
Magnetron Test in the Service manual) or measure the input current at full power and 50% power
level. Input current is approx. 8A at 50% power level operation and approx. 15A at full power
operation.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 293˚F(145˚C).
An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and
check inside of oven cavity and for improper setting of cooking time or operation of control unit. Check
for restricted air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
MAGNETRON TEMPERATURE FUSE TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds.
4. A continuity check across the temperature fuse terminals should indicate a closed circuit. If the
temperature of the magnetron reaches approximately 302˚F(150˚C), the temperature fuse opens. An
open temperature fuse indicates overheating of the magnetron. Check for restricted air flow to the
magnetron, especially the cooling fan air guide.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
CAUTION: IF THE THERMAL CUT-OUT OR TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT
AT ROOM TEMPERATURE, REPLACE THERMAL CUT-OUT OR TEMPERATURE FUSE.
C
OVEN THERMAL CUT-OUT TEST
+
0
∞
20
OK
NG
x 1
Ω
OK: Normal
NG: Defect
Q2
(B, E)
E C B
E C B
(B, E)
(C)
(C)
and
Q3
Q2
Q3
-
