41
1. High voltage is present at the high voltage terminal of the high voltage transformer during any cooking
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 28).
1. High voltage transformer
(A) Remove connections from the transformer
terminals and check continuity.
(B) Normal readings should be as follows:
Secondary winding.............Approx. 135
Ω
±10%
Filament winding ...............................Approx. 0
Ω
Primary winding.................................Approx. 0
Ω
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 9M
Ω
once the
capacitor is charged.
(C) A shorted capacitor will show constant 9M
Ω
.
(D) An open capacitor will show constant 9M
Ω
.
(E) Resistance between each terminal and chassis
should be infinite.
3. High voltage diode
(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-back resistance of the diode, otherwise
an infinite resistance may be read in both
directions. A normal diodes resistance will be
infinite in one direction and several hundred K
Ω
in the other direction.
4. Magnetron
For complete magnetron diagnosis, refer to
"Measurement of the Microwave Output
Power". (Page 24) 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
disconecting the leads.
(B) A continuity check across magnetron filament
terminals should indicate ohm or less.
(C) A continuity check between each filament
terminal and magnetron case should read
open.
5. Fuse
If the fuse in the primary monitor switch circuit is
blown when the door is opened, check the
primary interlock switch and monitor switch
before replacing the blown fuse. In case the fuse
is blown by an improper switch operation,
replace the defective switch and fuse at the
same time. Replace just the fuse if the switches
operate normally.
COMPONENT TEST PROCEDURE
CAUTION: REPLACE BLOWN FUSE WITH
15 AMPERE FUSE.
Содержание MFM-6D
Страница 46: ...45 Fig 9 Measurement Point ...
Страница 49: ...48 2 P C B CIRCUIT DIAGRAM MFM 6D ...
Страница 50: ...2 P C B CIRCUIT DIAGRAM MFM 7DTP 49 ...
Страница 52: ...51 4 PRINTED CIRCUIT BOARD ...
Страница 56: ...55 ...