Test And Checkout Procedures And Trouble Shooting; Test Procedures - Sears 721.80042 Basic Field Manual

TEST AND CHECKOUT PRECEDURES AND TROUBLESHOOTING
CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE
FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE LEAD WIRES FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF
WATER IN CONTAINER)IN THE OVEN.
A. TEST PROCEDURES
COMPONENTS
H.V.Transformer
MAGNETRON
1. Remove wire leads.
2. Measure resistance. (ohm meter scale: Rx1)
• Primary winding
• Secondary winding
• Filament winding
3. Measure resistance. (ohm meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
Antenna
1. Remove wire leads. Install the magnetron seal in
the correct position.
Check that the seal is in good condition.
2. Measure resistance. (ohm meter scale: Rx1)
• Filament terminal
3. Measure resistance. (ohm meter scale: Rx1000)
• Filament to chassis
7-15
TEST
Gasket
Chassis
RESULTS
Approx. 0.3 to 0.5 ohms
Approx. 65 to 120 ohms
0 ohm
Normal: Infinite
Normal: Infinite
Normal: Less than 1 ohm
Abnormal: Infinite
Normal: Infinite