Goldstar MA-2005ST, Service Manual

Page: 12 / 46

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4-3. WARNING - High voltage circuit ( 4,000 volt )
* The half-wave voltage doubler circuit consists of the secondary winding of
the high voltage transformer, H.V. diode (rectifier), and H.V. capacitor. The
H.V. diode allows alternating current (AC) to flow in one direction only and
rectifies it to pulsating direct current (DC).
The H.V. capacitor is able to store energy on one half of the AC cycle and
release it on the other half cycle.
* During the first half cycle of operation, the secondary winding of the
transformer supplies 2000 Volts to the capacitor current flows through the
diode and returns to the transformer for a complete circuit. This half-cycle
of AC charges the capacitor to approximately 2000 Volts.
* During the second half cycle of operation, the current flows in the opposite
direction, again supplies 2000 Volts to the circuit.
* This permits the capacitor to discharge its 2000 Volts on top of the 2000
Volts generated by the secondary winding, creating an approximate total
voltage of negative 4000 Volts D.C.
The negative 4000 Volts DC causes the magnetron to conduct current
and, to oscillate at 2450 MHz.
The first half cycle and the second half cycle become one complete cycle,
repeated input power frequency times per second .
INPUT
SENONDARY
WINDING AT
2000V
MAGNETRON
+
-
-
INPUT
SENONDARY
WINDING AT
2000V
MAGNETRON
+
-
-
+
INPUT
MAGNETRON
+ -
+
INPUT
MAGNETRON
+ -
+
-
SECONDARY
WINDING AT
2000V