LG MB390A Service Manual ▷ View online
5-8
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. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
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)
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
(Wire leads removed)
1. Measure the resistance.
(Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Ohm-meter scale: Rx1)
• Filament terminal
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Filament to chassis
• Filament to chassis
Approx.: 2.5
Ω
Approx.: 110
Ω
Less than: 0.4
Ω
Normal:
∞
Normal:
∞
Normal: Less than 1
Ω
Normal:
∞
PRIMARY
TERMINAL
TERMINAL
SECONDARY
TERMINAL
TERMINAL
FILAMENT
WINDING
TERMINAL
WINDING
TERMINAL
COMPONENT TEST PROCEDURE
5-8
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. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
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)
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
(Wire leads removed)
1. Measure the resistance.
(Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Ohm-meter scale: Rx1)
• Filament terminal
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Filament to chassis
• Filament to chassis
Approx.: 2.5
Ω
Approx.: 110
Ω
Less than: 0.4
Ω
Normal:
∞
Normal:
∞
Normal: Less than 1
Ω
Normal:
∞
PRIMARY
TERMINAL
TERMINAL
SECONDARY
TERMINAL
TERMINAL
FILAMENT
WINDING
TERMINAL
WINDING
TERMINAL
COMPONENT TEST PROCEDURE
5-8
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. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
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)
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
(Wire leads removed)
1. Measure the resistance.
(Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Ohm-meter scale: Rx1)
• Filament terminal
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Filament to chassis
• Filament to chassis
Approx.: 2.5
Ω
Approx.: 110
Ω
Less than: 0.4
Ω
Normal:
∞
Normal:
∞
Normal: Less than 1
Ω
Normal:
∞
PRIMARY
TERMINAL
TERMINAL
SECONDARY
TERMINAL
TERMINAL
FILAMENT
WINDING
TERMINAL
WINDING
TERMINAL
COMPONENT TEST PROCEDURE
5-8
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. (SEE PAGE 2-1)
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)
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)
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
(Wire leads removed)
1. Measure the resistance.
(Ohm-meter scale: Rx1 and Rx100)
• Primary winding
• Secondary winding
• Filament winding
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Primary winding to ground
• Filament winding to ground
• Primary winding to ground
• Filament winding to ground
1. Measure the resistance.
(Ohm-meter scale: Rx1)
• Filament terminal
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: Rx1000)
• Filament to chassis
• Filament to chassis
Approx.: 2.5
Ω
Approx.: 110
Ω
Less than: 0.4
Ω
Normal:
∞
Normal:
∞
Normal: Less than 1
Ω
Normal:
∞
PRIMARY
TERMINAL
TERMINAL
SECONDARY
TERMINAL
TERMINAL
FILAMENT
WINDING
TERMINAL
WINDING
TERMINAL
COMPONENT TEST PROCEDURE