6.2.2 Horizontal Drive and Output Circuit
<FIG. 14 Horizontal Drive and Output Circuit>
The horizontal oscillator output from terminal 10 of
IC401
feeds the base of
H.
driver amplifier transistor
0503.
The amplified output passes through the drive transformer into the horizontal output transistor
0504.
The horizontal drive circuit generates a large drive current
of
the horizontal output trahsistor
0504.
The power to the collector of
0504
comes from
B+
and the primary coil of the drive transformer.
Although the base current of
0503
is
in
phase with the collector current, the voltage waveforms
are
out of phase.
The collector currentis cut off and the collector voltage rises when the base voltage reaches zero.
When the collector current rapidly drops' off, retrace capacitors
C526, C527 and C528 damp out high frequency
ringing caused by the drive transformer. Excessive ringing may reduce the drive current or
cause
abnormal
oscillations, thereby destroying the horizontal output transistor. Horizontal drive transformer steps
up
the current
to sufficient levels
to
drive 0504.
The horizontal output transistor switches with the pulse voltage supplied by the horizontal drive transformer and
drives the deflection coil wtih a sawtooth current waveform.
31
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