Electrolux MCC4060E Service Manual page 22

PROCEDURE
LETTER
C HIGH VOLTAGE RECTIFIER TEST
D
SOI 12.06 FV
TEST PROCEDURES
CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage
rectifier can be tested using an ohmmeter set to its highest range. Connect the
ohmmeter across the terminal B+C of the high voltage rectifier and note the
reading obtained. Reverse the meter leads and note this second reading.
The normal resistance is infinite in one direction and more than 100
other direction.
CARRY OUT 4R CHECKS
ASYMMETRIC RECTIFIER TEST
CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric
rectifier can be tested using an ohmmeter set to its highest range across the
terminals A+B of the asymmetric rectifier and note the reading obtained.
Reverse the meter leads and note this second reading. If an open circuit is
indicated in both direction then the asymmetric rectifier is good. If an
asymmetric rectifier is shorted in either direction, then the asymmetric rectifier
is probably faulty and must be replaced with high voltage asymmetric rectifier.
When the asymmetric rectifier is defective, check whether magnetron, high
voltage rectifier, high voltage wire or filament winding of the high voltage
transformer is shorted.
CARRY OUT 4R CHECKS
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER,
THE BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE
A VOLTAGE OF AT LEAST 6 VOLTS, BECAUSE OTHERWISE AN
INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH
DIRECTIONS.
HIGH VOLTAGE CAPACITOR TEST
CARRY OUT 3D CHECKS
A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set
to the highest resistance range.
C. A normal capacitor shows continuity for a short time (kick) and then a
resistance of about 10
D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10
its internal 10 MΩ resistance.
F. When the internal wire is opened in the high voltage capacitor, the
capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite
when the capacitor is normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.
CARRY OUT 4R CHECKS
COMPONENT TEST
ASYMMETRIC
RECTIFIER
MΩ after it has been charged.
22/43
kΩ in the
HIGH VOLTAGE
RECTIFIER
MΩ because of
599 37 42-75