Sync / Deflection Block; Cpu Ic1001 & Dpu Ic801 - Sony CPD-G400 Training Manual

Sync / Deflection Block

Several stages can be grouped together to provide the CRT with basic
operating signals. These stages run independent of the video circuitry
and are self-sustaining. The main stages in this block are:
Deflection Block
Stages
CPU IC1001 Horizontal & Vertical Oscillator, Protection
circuit, Data control.
DPU IC801 •
H & V waveform shaping for each monitor
mode
•
Pincushion correction signal
•
Picture rotation
•
Dynamic Focus
•
Convergence signals
High Voltage Generation and regulation.
Horizontal Deflection CRT beam sweep
Pincushion Corrects for black left and right bowed areas
Vertical Defection CRT beam sweep
CPU IC1001 & DPU IC801
When the monitor is turned ON, the horizontal and vertical oscillators
inside the CPU IC1001 produce an output. These oscillators run at de-
fault frequencies of 70kHz and 80Hz respectively until sync is input to
change these two frequencies. The DPU IC801 shapes the horizontal
signal into the correct pulse width (picture size) and the vertical signal into
the correct ramp size and linearity.
High Voltage
The HD signal from the DPU IC801 is used for horizontal sweep and high
voltage generation. The HD signal is amplified and buffered in the drive
stage (Q501-Q503) before being spit into two paths. The first path is into
the High Voltage stage (IC901, Q901-2). This stage uses the horizontal
signal to generate high voltage. The high voltage level is regulated using
Function
left to right
top to bottom
49
a sample of fly back (FBT T901) voltage. The fly back causes the remain-
der of the voltages for the CRT to operate. The CPU uses a sample of the
HV voltage and ABL voltage (CRT current) from the FBT for protection.
The CPU will latch the monitor into the low power mode when there is
excessive voltage or current.
Horizontal Deflection & Pincushion
The Horizontal Output stage (Q504) uses the amplified HD signal to pro-
vide sufficient sweep to deflect the electron beam across the CRT screen.
The CPU monitors the output in case of a sweep failure (protect) and
enters the low power mode without a sweep signal.
The H Shape signal from the DPU IC801 is used in the pincushion stage
(IC501, Q506, Q508, Q509). This signal is also known as "E/W" (east/
west) because it is used to correct the inability of tordial yokes to provide
extra deflection at the middle of the picture. This is why early picture
tubes were round. East and west were used to designate the black areas
at the left and right sides of the screen that required correction. Extra
sweep current from the pincushion stage is applied to the yoke to elimi-
nate the black areas.
black
Pincushion Distortion
Vertical Deflection
The V Saw In signal from the DPU IC801 is used in the Vertical Output
stage. This stage sweeps the CRT electron beam from top to bottom.
The oscillator in the CPU (IC10101) controls the speed. The DPU (IC801
controls the vertical size and linearity by shaping the sawtooth signal that
is output. IC401 has its own internal voltage generator to make extra
voltage required during vertical retrace when the output voltage is double
the main ramp voltage. A failure in this internal voltage generator will
cause no deflection or poor linearity. A line will be burned into the CRT
within a second during a vertical or horizontal deflection failure. For pro-
tection from a CRT line burn, the internal voltage generator pulse repre-
sents vertical output operation. The CPU monitors this signal and latches
the monitor into the low power when there is a loss of the protect signal.
Insufficient
scan -
black