– 57 –
Check for 240V at transformer. Disconnect transformer 3-pin connector.
Power up microwave in service mode. Check voltage between pins 1 and 3
(black and purple) on harness side. Note: If voltage is less than 210, voltage
will be between pins 1 and 2 (black and yellow).
Is there 240V at the transformer?
No
Replace the
magnetron and retest
(see note).
Check mag connector. Check grounds. Verify ground
from magnetron to transformer mounting screw.
Check capacitor and wiring.
Yes
Measure diode resistance in both directions
(must read open in at least one direction).
Check microwave fuse.
Measure transformer primary resistance
(1.1 +/- 0.2 ohms between pins 1 and 3 of
the connector).
Measure transformer secondary resistance
(90 +/- 4 ohms between ground and single
wire capacitor). Note if HVT warm resistance
will be higher.
Ohm out right interlock, left
interlock, and monitor switches
(see page 24).
Check door sense switch (see
page 24).
Check relay board (SWO
board). Disconnect right
interlock connector. Check
voltage from pin 1 of harness
side of connector (black wire) to
J105 on board (yellow wire).
Check harness for
bad connection.
Correct and retest.
Note: Insure magnetron fan and stirrer motor
are operating properly. Failure of either of these
can lead to failure of high-voltage
component(s).
WARNING: High voltage system is at 4400V. Disconnect power and discharge capacitor before touching transformer, diode, capacitor, magnetron
or any wiring between these components.
No Microwave Power
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