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EN 96
9.
DPTV465
transistor turned "off". In the same manner, the Negative
Horizontal pulses keep the base of 7810 at a negative voltage
to keep it turned "off". The Protect line is normally Low, keeping
7809 turned "off". The +200-volt source is fed through zener
diodes 6812 and 6816, resistor 3850, the base-emitter of 7906,
the base emitter of 7812 to keep transistor 7813 turned "on".
This turns transistor 7814 "on", which switches the "on" voltage
to the High Voltage module. The conduction of 7812 keeps the
voltage on the G1 line at approximately - 18 Volts, which turns
the CRTs "on". If the Vertical Pulse should fail, transistor 7808
will turn "on", which will turn 7906, 7812, 7813, and 7814 "off".
This will turn the HVG module "off". In addition when 7812 turns
Convergence processor
Figure 9-34 Convergence signal processor
The Convergence data is stored in the EEPROM, 7000. The
microprocessor located on the ASC module reads 1,971 bytes
of data from 7000 and writes it to the Convergence Processor,
7002. Horizontal sync is inverted by 7026, buffered by 7025,
and fed to pin 27 of 7002. Vertical sync is inverted by 7027,
buffered by 7028, and fed to pin 28 of 7002. The data is
processed to produce the desired convergence correction
waveforms, which are output on six DACS. During the
convergence adjustment procedure, a 180-point alignment grid
is output on Pins 16, 17, and 18. This signal is mixed with the
OSD to be displayed on the screen. In the 4x3 aspect ratio set,
there are three sets of convergence data. In sets with a 16x9
aspect ratio, there are two sets of convergence data. The set
will require convergence alignment for each set of convergence
data. The correct mode must be selected and the signal for that
mode must be applied to the set during the convergence
alignment. The output of the DACS is fed to six op-amps before
being fed to the Power Amplifiers located on the SSM. When
screen centring is being performed, it is necessary to disable
the convergence drive waveform. A High on pin 77 turns
transistor 7029 "on", turning 7038 "on", which turns transistors
7032, 7033, 7030, 7031, 7034, and 7035 "on". This mutes the
correction drive signal to the Power Amplifiers.
Circuit Descriptions, List of Abbreviations, and IC Data Sheets
9.3.27 Convergence
E_15000_099.eps
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"off", the G1 voltage will go to -200 Volts, blanking the CRTs.
The same sequence will occur if Horizontal should fail, the
Protect line should go "high", or the +200 Volt source should
fail.
The Convergence system is split into two sections. The
convergence signal processor is located on the ACS (Auto
Convergence System) module. The output amplifiers are
located on the SSM (Small Signal Module).
Intellisense Sensor Locations
2
Figure 9-35 Sensor locations
The Philips Intellisense system makes minor Convergence
corrections when the feature is selected by the Customer.
When a PTV is moved from one location to another, minor
Convergence errors will occur due to changes in the Earths
magnetic field. When Save is selected during the Convergence
Alignment, the set scans four optical sensors with each of the
three colours. The locations of these sensors are recorded by
the ACS microprocessor. When the Customer selects the
Intellisense feature, the sensors are again scanned and the
rotation of the beams for each colour is adjusted to the
recorded values.
1
3
4
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