Whirlpool MH2175XSB Service Guide - Page 45

Troubleshooting

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DIAGNOSIS & TROUBLESHOOTING Interlock Switch Checkout Procedures Switch Check By Primary Interlock 1. Unplug microwave oven or disconnect power. 2. Disconnect the wires at the Primary Interlock Switch. 3. Check from the common terminal (black/brown wires) to the normally open terminal (black/white wires). 1. Unplug microwave oven or disconnect power. 2. Disconnect the wires at the Primary Interlock Switch. 3. Check from the common terminal (black/brown wires) to the normally closed terminal (orange wire). Secondary Interlock 1. Unplug microwave oven or disconnect power. 2. Disconnect the wires at the Secondary Interlock Switch. 3. Check from the common terminal (blue/white wires) to the normally open terminal (blue wires). Monitor Interlock 1. Unplug microwave oven or disconnect power. 2. Disconnect the wires at the Monitor Interlock Switch. 3. Check from the common terminal (white wire) to the normally closed terminal (blue/white wires). (+) Continuity (-) No Continuity Door Open Door Closed - + + - - + + - NOTE: These diagrams are not intended to show a complete circuit; they represent the position of switches during "DOOR OPEN" or "DOOR CLOSED" (continuity checks only). Door Closed Door Open L (NC) (NO) (NC) N (NO) (NC) (NO) Primary Interlock Switch Monitor Interlock Switch Secondary Interlock Switch L (NC) (NO) (NO) (NC) N (NC) (NO) Primary Interlock Switch Monitor Interlock Switch Secondary Interlock Switch TROUBLESHOOTING Do not continue with the diagnostics of appliance if the household fuse is blown, a circuit breaker is tripped or if there is less than 120-volt power supply at the wall outlet. Complete the following steps before checking microwave oven circuitry: 1. Unplug microwave oven or disconnect power. 2. Check for loose wiring or incorrect wiring within microwave oven. 3. Disconnect white wire from power transformer and discharge high-voltage capacitor. 4. All testing must be done with an ohmmeter having a sensitivity of 20,000 ohms per volt DC or greater, and powered by at least a 9-volt battery. 5. All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 8 oz (250 mL) of water in a microwave safe container. 6-1

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6-1
DIAGNOSIS & TROUBLESHOOTING
(+) Continuity
(-) No Continuity
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Primary
Interlock
1.
Unplug microwave oven or disconnect power.
2.
Disconnect the wires at the Primary Interlock Switch.
3.
Check from the common terminal (black/brown wires) to the
normally open terminal (black/white wires).
-
+
1.
Unplug microwave oven or disconnect power.
2.
Disconnect the wires at the Primary Interlock Switch.
3.
Check from the common terminal (black/brown wires) to the
normally closed terminal (orange wire).
+
-
Secondary
Interlock
1.
Unplug microwave oven or disconnect power.
2.
Disconnect the wires at the Secondary Interlock Switch.
3.
Check from the common terminal (blue/white wires) to the
normally open terminal (blue wires).
-
+
Monitor
Interlock
1.
Unplug microwave oven or disconnect power.
2.
Disconnect the wires at the Monitor Interlock Switch.
3.
Check from the common terminal (white wire) to the normally
closed terminal (blue/white wires).
+
-
INTERLOCK SWITCH CHECKOUT PROCEDURES
NOTE: These diagrams are not intended to show a complete circuit; they represent the position of switches during “DOOR
OPEN” or “DOOR CLOSED” (continuity checks only).
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TROUBLESHOOTING
Do not continue with the diagnostics of appliance if the
household fuse is blown, a circuit breaker is tripped or if there
is less than 120-volt power supply at the wall outlet.
Complete the following steps before checking microwave
oven circuitry:
1.
Unplug microwave oven or disconnect power.
2.
Check for loose wiring or incorrect wiring within
microwave oven.
3.
Disconnect white wire from power transformer and
discharge high-voltage capacitor.
4.
All testing must be done with an ohmmeter having a
sensitivity of 20,000 ohms per volt DC or greater, and
powered by at least a 9-volt battery.
5.
All operational checks using microwave energy must be
done with the microwave oven loaded with a minimum of
8 oz (250 mL) of water in a microwave safe container.
Monitor
Interlock
Switch
Secondary
Interlock
Switch
Primary
Interlock
Switch
(NC)
(NO)
(NC)
(NO)
(NC)
(NO)
L
N
Monitor
Interlock
Switch
Secondary
Interlock
Switch
Primary
Interlock
Switch
(NC)
(NO)
(NC)
(NO)
(NC)
(NO)
N
L