MEASUREMENT AND TEST
3. COMPONENT TEST PROCEDURE
High voltage is present at the high voltage term inal of the high voltage transform er during any cooking cycle.
It is neither necessary nor advisable to attem pt m easurem ent of the high voltage.
Before touching any oven components or wiring, always unplug the oven from its power source and discharge the capacitor.
1. High voltage transformer
1) Rem ove connections from the transform er term inals and check continuity.
2) Norm al readings should be as follows :
Secondary winding ... Approx. 110
± 10%
Filam ent winding ... Approx. 0
Prim ary winding ... Approx. 1
2. High voltage capacitor
1) Check continuity of capacitor with m eter on the highest O HM scale.
2) A norm al capacitor will show continuity for a short tim e, and then indicate 10M
once the capacitor charged.
3) A shorted capacitor will show continuous continuity.
4) An open capacitor will show constant 10M
.
5) Resistance between each term inal and chassis should be infinite.
3. High voltage diode
1) Isolate the diode from the circuit by disconnecting the leads.
2) W ith the ohm m eter set on the highest resistance scale m easure the resistance across the diode term inals. Reverse
the m eter leads and again observe the resistance reading. M eter with 6V, 9V or higher voltage batteries should be
used to check the front-back resistance of the diode, otherwise an infinite resistance m ay be read in both directions. A
norm al diode's resistance will be infinite in one direction and several hundred k
in the other direction.
4. Magnetron
For com plete m agnetron diagnosis, refer to “M easurem ent of the M icrowave Power O utput. " Continuity checks can only
indicate and open filam ent or a shorted m agnetron. To diagnose for an open filam ent or a shorted m agnetron,
1) Isolate m agnetron from the circuit by disconnecting the leads.
2) A continuity check across m agnetron filam ent term inals should indicate 0.1
or less.
3) A continuity check between each filam ent term inal and m agnetron case should read open.
5. Fuse
If the fuse in the prim ary and m onitor switch circuit is blown when the door is opened, check the prim ary and m onitor
switch before replacing the blown fuse. In case the fuse is blown by an im proper switch operation, replace the defective
switch and fuse at the sam e tim e. Replace just the fuse if the switches operate norm ally.