LG LTM9020B, Service Manual

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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 WIRE LEADS 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.
COMPONENTS TEST PROCEDURE RESULTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
1. Measure the resistance.
(Select the ohm scale on the meter)
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Select the ohm scale on the meter)
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Select the ohm scale on the meter)
• Filament terminal
2. Measure the resistance.
(Select the ohm scale on the meter)
• Filament to chassis
Approx.: 0.7 ~ 0.9 ohm
Approx.: 90 ~ 120 ohm
Less than: 1 ohm
Normal: Infinite
Normal: Infinite
Normal: Less than 1 ohm
Normal: Infinite
FILAMENT
WINDING
PRIMARY
TERMINAL
SECONDARY
WINDING
11. TEST AND CHECKOUT PROCEDURES, AND TROUBLESHOOTING
A. TEST PROCEDURES