For Service Technician Use Only
DIAGNOSTICS (Cont.)
2-6
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Low Profile Microwave Hood Combination
NOTES:
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Below 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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Interlock and Monitor switches cannot be adjusted and all
these switches should be replaced if any one of them is found
to be defective. After replacing interlock/monitor switches,
reconnect wires to switch and check for continuity.
Not Heating Troubleshooting Instruction
IMPORTANT:
High-voltage is present at the magnetron and high-
voltage capacitor terminals. Avoid direct contact when power
is connected to these components to avoid serious injury or
possible death. Always be sure that the high-voltage capacitor is
discharged before accessing any of these components.
For a no-heat condition, refer to the following step-by-step
instructions:
1.
Unplug microwave oven or disconnect power.
2.
Discharge the high-voltage capacitor.
3.
Disconnect the high-voltage transformer primary windings.
4.
Attach the voltmeter leads to the high-voltage transformer
primary input wires.
5.
Plug in microwave oven or reconnect power.
6.
Close door and program the microwave oven to operate for
30 seconds.
7.
Press START.
8.
Check the input voltage at the high-voltage transformer
primary input wires. If the voltage is not close to the rating
voltage 120 ± 15 VAC, unplug microwave oven or disconnect
power. Check the circuitry as follows:
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Measure resistance of the fuse, micro-switches, and
thermostats. Replace any failed components. (Refer to
the wiring diagram.)
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Check for loose terminals. (Refer to the wiring diagram.)
Check all of the terminals on the main route from the
power supply to the high-voltage transformer.
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Check for loose or failed connectors on the PCBA
(P1, P2). If these check out OK, plug in microwave oven or
reconnect power.
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Check for ACU failure. Refer to “ACU Pin Voltage Matrix.”
9.
If the input voltage at the high-voltage transformer primary
input wires is close to the rating voltage 120 ± 15 VAC, unplug
microwave oven or disconnect power.
10.
Check the power supply components. Refer to “Component
Tests.”
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High-voltage transformer
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High-voltage capacitor
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High-voltage diode
11.
If the power supply components check out OK, check the
connection between the magnetron and the high-voltage
transformer.
12.
If all of the components check out OK, replace the
magnetron.
13.
Reconnect the high-voltage transformer primary windings.
N
(NO)
(NC)
Monitor
Interlock
Switch
Primary
Interlock
Switch
(NC)
(NO)
Secondary
Interlock
(NC)
Switch
P5-4
(NO)
P5-2
L
(NO)
(NC)
P2-2
Door
Interlock
Switch
N
(NO)
(NC)
Monitor
Interlock
Switch
Primary
Interlock
(NC)
Switch
(NO)
Secondary
Interlock
Switch
(NC)
P5-4
(NO)
P5-2
L
(NC)
(NO)
P2-2
Door
Interlock
Switch
Door Closed
Door Open
