Component Test Procedure - Daewoo KOC-872T0S Service Manual

COMPONENT TEST PROCEDURE

1. High voltage is present at the high voltage terminal of the high voltage transformer during any cook cycle.
2. It is neither necessary nor advisable to attempt measurement of the high voltage.
3. Before touching any oven components or wiring, always unplug the oven from its power source and discharge the
capacitor (see page 20).
1. High voltage transformer
(A) Remove connections from the transformer terminals and
check continuity.
(B) Normal readings should be as follows:
Secondary winding
Filament winding
Primary winding
Filament terminal
Primary
terminal
2. High voltage capacitor
A) Check continuity of capacitor with meter on the highest
ohm scale.
(B) A normal capacitor will show continuity for a short time,
and then indicate 9MΩ once the capacitor is charged.
(C) A shorted capacitor will show continuous continuity.
(D) An open capacitor will show constant 9MΩ.
(E) Resistance between each terminal and chassis should
be infinite.
3. High voltage diode
The high voltage diode is located on the base near the
transformer.
(A) Isolate the diode from the circuit by disconnecting the
leads.
(B) With the ohmmeter set on the highest resistance scale,
measure the resistance across the diode terminals.
Reverse the meter leads and again observe the
resistance reading. Meter with 6V, 9V or higher voltage
batteries should be used to check the front-to-back
resistance may be read in both directions. A normal
diodes resistance will be infinite in one direction and
several hundred KΩ in the other direction.
Approx. 100Ω ¡ 10%
Approx. 0Ω
Approx. 0Ω
Secondary
terminal
26
4. Magnetron
For complete magnetron diagnosis, refer to "Measure-
ment of the Microwave Output Power".
Continuity checks can only indicate and open filament or
a shorted magnetron. To diagnose for an open filament
or shorted magnetron.
(A) Isolate magnetron from the circuit by disconnecting the
leads.
(B) A continuity check across magnetron filament terminals
should indicate one ohm or less.
(C) A continuity check between each filament terminal and
magnetron case should read open.
Magnetron
antenna
Metallic
gasket
plate
Filament
terminal
Magnetron
chassis
ground