Dac & Lpf Circuitry - Mitsubishi Electric VS-45605 Technical Training Manual

The signals from IC800 are directed to Digital to
Analog Converters in IC8E01, IC8E02 and IC8E03.
Each of the ICs is comprised of two separate Digital
to Analog Converters. The analog outputs of the D/
A Converters are directed to Low Pass Filter (LPF)
circuitry in IC802, IC803, and IC804.
The outputs from the LPF circuitry are applied to
amplifiers in the second stage of IC802, IC803, and
IC804. The Green signal is also directed to the Red
and Blue Amplifier inputs.
adjustments are performed on the Green raster, but
also effect the Red and Blue rasters.
The six amplified signals are directed to their respec-
tive Convergence Output IC. The Convergence Out-
put ICs, IC8C01 and IC8C02, contain three sepa-
rate amplifiers. IC8C01 amplifies the horizontal cor-
rection signals, and IC8C02 the vertical correction
signals.
An oscilloscope can be used to trace the signal
through the circuitry to isolate a problem area. Not
much can be told from the serial digital signals, ex-
cept that the signals are present.
The raster correction
Page 4-3
DAC & LPF Circuitry
Figure 4-3 illustrates the circuitry of one Digital/Ana-
log Converter IC, and its associated LPF circuitry.
All three DAC and LPF circuits are the same, except
for component nomenclature. The component no-
menclature that is given in Figure 4-3, is common to
all three circuits.
As stated earlier, each DAC IC has two internal Digi-
tal to Analog Converters. Serial data is input to D/A
#1 at pin 15, and data for D/A #2 is input at pin 14.
The timing signals for the internal converters, are
common to all three DAC ICs,
• CLK -- input to the IC at pin 16.
• WDCLK -- input at pin 13
The charges on the capacitors at pins 9 and 10, are
the reference voltages for the internal converters. The
D/A #1 analog signal is output at pin 11, and D/A #2
signal is output at pin 6. The two signals are di-
rected to LPF circuitry in the Low Pass Filter IC.
The LPF circuitry receives DC power from the plus
and minus 9 Volt supplies. The IC, and its external
circuitry, removes the high frequency components