Sanyo VPC-E6 Service Manual page 6

1-4. ST1 STROBE CIRCUIT DESCRIPTION
1. Charging Circuit
When UNREG power is supplied to the charge circuit and the
CHG signal from microprocessor becomes High (3.3 V), the
charging circuit starts operating and the main electorolytic
capacitor is charged with high-voltage direct current.
However, when the CHG signal is Low (0 V), the charging
circuit does not operate.
1-1. Charging switch
The CHG signal becomes High, Q5406 becomes ON and the
charging circuit starts operating.
1-2. Power supply filter
C5406 constitutes the power supply filter. They smooth out
ripples in the current which accompany the switching of the
oscillation transformer.
1-3. Oscillation circuit
This circuit generates an AC voltage (pulse) in order to in-
crease the UNREG power supply voltage when drops in cur-
rent occur. This circuit generates a drive pulse with a frequency
of approximately 50-100 kHz. Because self-excited light omis-
sion is used, the oscillation frequency changes according to
the drive conditions.
1-4. Oscillation transformer
The low-voltage alternating current which is generated by the
oscillation control circuit is converted to a high-voltage alter-
nating current by the oscillation transformer.
1-5. Rectifier circuit
The high-voltage alternating current which is generated at
the secondary side of T5401 is rectified to produce a high-
voltage direct current and is accumulated at electrolytic ca-
pacitor C5412.
1-6. Voltage monitoring circuit
This circuit is used to maintain the voltage accumulated at
C5412 at a constance level.
After the charging voltage is divided and converted to a lower
voltage by R5405 and R5406, it is output as the monitoring
voltage VMONIT. When VMONIT voltage reaches a specified
level, the CHG signal is switched to Low and charging is in-
terrupted.
2. Light Emission Circuit
When FLCLT signals are input from the ASIC expansion port,
the stroboscope emits light.
2-1. Emission control circuit
When the FLCLT signal is input to Hi at the emission control
circuit, Q5409 switches on and preparation is made to the
light emitting. Moreover, when a FLCLT signal becomes Lo,
the stroboscope stops emitting light.
2-2. Trigger circuit
The Q5409 is turned ON by the FLCLT signal and light emis-
sion preparation is preformed. Simultaneously, high voltage
pulses of several kV are emitted from the trigger coil and ap-
plied to the light emitter.
2-3. Light emitting element
When the high-voltage pulse form the trigger circuit is ap-
plied to the light emitting part, currnet flows to the light emit-
ting element and light is emitted.
Beware of electric shocks.
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