Table of Contents
Advertisement
F-6. Degauss Ckt
The DEGU signal which comes from micro-p to control degauss coil act or not.
When DEGU is high, Q950 will be saturated to make RL901 working, AC line provides
a degaussing current to degauss coil.
F-7. OVERLOAD PROTECTION CKT
The primary current flows through the current sensing resistor R914. The voltage drop on R914 will be
rectified by D927 and keep a DC level on C927 that is dependent on the output power. When this DC level
reach the trigger voltage of Q920, the pin 1 of U901 goes low and the power stage is immediately switched
off.
F-8. BROWN – OUT CKT
When the input voltage down below the setting level (85Vac-75Vac), Q904 will be supplied a trigger voltage
to make Q920 turn on and this time, power supply shall be shut down.
G. Deflection
G-1. Sync Processor
H-sync & V-sync or input to U1(u-P), then u-P output the H-out & V-out to
U401 (TDA4858).
G-2. Hor. Processor & Vert. Pre-Amp
Fig.2 is the block diagram of IC TDA4858.
Hor. Processor
The H-out that come from u-P will input to the pin 15 of U401,it will be compared
with the oscillator sawtooth voltage by the PLL1(pin 26) phase detector, After that, it will be compared again
with the flyback pulse (pin 1) by the PLL2. The PLL2 detector thus compensates for the delay in the external
horizontal deflection circuit by adjusting the phase of the HDRV(pin 7) output pulse.
+B control
The U401 pin 5 to pin 3 is Operation Amplifier from pin 11 EW DRV parabola amplitude DC, H-Size and
Trapezium correction wave from connection, pin 6 is forward PWM output, driver the Q420, Q422 all mode
+B is 180V
Vert. Pre-am
Vertical oscillator will be triggered by V-out (pin 14). It is available to get sawtooth waveform in pin 24.
V-center, V-amp and V-linearity can be adjusted in pin 17, 18 and 19. The vertical output driver comes from
pin 12 and 13.
22
Advertisement
Table of Contents
