Component Test Procedure - LG MH-1355M Service Manual

COMPONENT TEST PROCEDURE

CAUTIONS
1. DISCONNECT THE POWER SUPPLY CORD FROM THE WALL OUTLET WHENEVER REMOVING
THE OUT 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 FIGURE 24)
2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER
OF WATER IN A BEAKER) IN THE OVEN.
WIRE SEADS (WHITE, WHITE)
FOR PRIMARY WINDING
• TEST PROCEDURE
COMPONENTS
HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)
MAGNETRON
(Wire leads removed)
FILAMENT
WINDING
WIRE LEAD (RED, RED)
FOR PRIMARY WINDING
TEST PROCEDURE
See Fig 24.
1. Measure the resistance.
(Ohm-meter scale: R x 1)
• Primary winding
• Secondary winding
• Filament winding
2. Measure the resistance.
(Ohm-meter scale: R x 1000)
• Primary winding to ground
• Filament winding to ground
See Fig 25.
1. Measure the resistance.
(Ohm-meter scale: R x 1)
• Filament terminal
2. Measure the resistance.
(Ohm-meter scale: R x 1000)
• Filament to chassis
– 36 –
SECONDARY TERMINAL
H.V. CABLE ASM-A
Fig. 24
RESULTS
Approx.: 0.37 ohm (at 20 °C)
Approx.: 90 ohm (at 20 °C)
Less than: 0.9 ohm
Normal: Infinite
Normal: Infinite
Normal: Less than 1 ohm
Normal: Infinite