Hitachi 46W500 Training page 60

DP-3X HORIZONTAL DRIVE CIRCUIT EXPLANATION
If there is a difference between the two voltages, an error voltage is generated and output from pin (10) and input
again at pin (11) where it manipulates the PWM (Pulse With Modulation) signal producing the Horizontal Drive
signal output from pin (1).
It's important to notice that the High Voltage circuit can not function without the Horizontal Deflection circuit
providing a drive signal. The Sweep Loss circuit will since the loss of H. Blanking and output a high that's routed
through DN10 to pin 3 and DN09 to pin 14. If these voltages go high, pin 3 will defeat the H. Drive by saturating
the internal op-amp that creates the sawtooth comparator signal. Thus stopping H. Drive. Pin 14 high will satu-
rate the internal generator that produces the sine wave for the sawtooth op-amp. See Figure 1 below.
GENERAL INFORMATION:
The DP-3X deflection circuit differs from analog Hitachi projection televisions. It utilizes in a sense, two hori-
zontal output circuits. One for Deflection and one for High Voltage. This allows for better deflection stabilization
and is not influenced by fluctuations of the High Voltage circuit which may cause unacceptable breathing and
side pulling of the deflection.
3
Gen
9
DC Feed Back
12
DC Ref.
-
+
DC Ref.
+
-
+
1
-
10 11
Fig 1
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