Daewoo KOR-1N4A9W Service Manual

Daewoo KOR-1N4A9W Service Manual Manual pdf 24 page image

233. COMPONENT TEST PROCEDURE• High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle.• It is neither necessary nor advisable to attempt measurement of the high voltage.• Before touching any oven components or wiring, always unplug the oven from its power source and discharge thecapacitor.1. High voltage transformer1) Remove connections from the transformer terminals and check continuity.2) Normal readings should be as follows :Secondary winding ... Approx. 140 Ω ±10%Filament winding ... Approx. 0 ΩPrimary winding ... Approx. 2 Ω2. High voltage capacitor1) Check continuity of capacitor with meter on the highest OHM scale.2) A normal capacitor will show continuity for a short time, and then indicate 10MΩ once the capacitor charged.3) A shorted capacitor will show continuous continuity.4) An open capacitor will show constant 10MΩ.5) Resistance between each terminal and chassis should be infinite.3. High voltage diode1) Isolate the diode from the circuit by disconnecting the leads.2) 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-back resistance of the diode,otherwise an infinite resistance may be read A normal diode s resistance will be infinite in one direction andseveral hundred KΩ. in the other direction.4. MagnetronFor complete magnetron diagnosis, refer to "Measurement of the Microwave Power Output." Continuity checks canonly indicate and open filament or a shorted magnetron. To diagnose for an open filament or a shorted magnetron,1) Isolate magnetron from the circuit by disconnecting the leads.2) A continuity check across magnetron filament terminals should indicate 0.1 Ω or less.3) A continuity check between each filament terminal and magnetron case should read open.5. FuseIf the fuse in the primary and monitor switch circuit is blown when the door is opened, check the primary andmonitor switch before replacing the blown fuse. In case the fuse is blown by an improper switch operation, replacethe defective switch and fuse at the same time. Replace just the fuse if the switches operate normally.6. Interlock switches1) You can test continuity of safety interlock and monitor switch by using ohmmeter.2) The switch operation is checked by zero/unlimited.The meter should indicate zero resistance.3) The sequence of check is interlock monitor switch, primary and secondary interlock switches check.