Horizontal Output Circuit; High Voltage And Dynamic Drive; Vertical Amplifier - Philips DPTV400 Series Training Manual

Horizontal Output circuit (Figure 11)
Horizontal drive from the HOP circuit on the SSM is fed to 7807 on the Large Signal panel.
Transistor 7807 drives the Horizontal Output Transistor 7801, which drives the Yokes and the
Horizontal Output Transformer 5801. Transformer 5801 produces a plus and minus 13-volt supply
for the Vertical Output circuit. Voltage from Pin 7 of 5801 is rectified by 6802 to produce the +200-
volt supply for the CRTs. Voltage from Pin 5 is rectified by 6801 to produce the Filament voltage.
This voltage is filtered by 2804 to provide approximately 6 volts DC. This circuit is protected by fuse
1801 and resistor 3801. The negative Horizontal pulse from Pin 5 feeds the Blanking and Sweep
failure detection circuit.
The output of 7807 drives IC 7803 and transistor 7802. This circuit drives the Dynamic Focus and
Horizontal Geometry correction. The Horizontal component of the correction drives the return side
of the Horizontal yokes via the DYN-FOCUS-HIGH and DYN-FOCUS-LOW lines.
High Voltage and Dynamic drive (Figure 12)
The High Voltage module is an integrated High Voltage supply with its own switching power supply.
When the set is turned On, approximately 10 to 11 volts from the Sweep Failure detection circuit is
fed to diode 6913 and to Pin 8 of the High Voltage module. A supply voltage of 130 volts is also fed
to Pin 10 of the module. The Module then outputs High voltage to the three CRTs. It also outputs
Focus voltage to the Focus G2 block. Output on Pin 4 is rectified by 6917 to produce a negative
200-volt source for the CRT G1 voltage. The voltage is also rectified by 6919 to produce a 330-volt
source for the Dynamic Focus drive. The Dag line along with the output on Pin 2 is connected to
7903 to produce the ABL voltage for the set. If an overcurrent condition should develop with the
drive, the ABL voltage will go Low, turning 7905 On, latching 7904, which will remove drive to Pin 8
of the HVG. This will cause the High voltage to shut Off. The DM-INPUT is mixed with the East
West drive EWO and fed to transistor 7903 which drives 7901. Transistor 7901 drives the Dynamic
Focus and geometry correction drive which is fed to the return side of the Horizontal Yokes via the
DYN-FOCUS-LOW and DYN-FOCUS-HIGH connections.
Vertical Amplifier (Figure 13)
The Vertical drive from the HOP panel drives the Vertical Output IC 7811. This IC is located on the
Large Signal panel. Drive is fed to Pin 7 and is output on Pin 5 to drive the three Vertical Yokes.
This IC is powered by the plus and minus 13-volt supplies from the Horizontal Output circuit. A
Vertical pulse on Pin 6 is fed to the sweep failure detection circuit. If there is a failure in the
Horizontal or Vertical sweep, the High Voltage will be shut down.
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