1. The front stage circuit of TMPA8803/CH0TO601 internal field scanning is shown in Figure 1. The internal stage of the TMPA8803/CH08T0601 internal field scanning circuit consists of external circuits of pins 15 and 16. There is no separate field oscillating circuit in the TMPA8803. The field frequency pulse is generated by dividing the horizontal frequency pulse in the field divider. At the same time, the field synchronization separation circuit inside the N201 performs field synchronization separation on the composite synchronization signal separated by the synchronous separation circuit to separate the field synchronization signal, and the separated field synchronization signal is also sent to the field frequency divider to control the field frequency divider. The working state is such that the field frequency pulse generated by the field frequency divider and the field synchronization signal in the signal transmitted by the television station are always at the same frequency and in phase. The field frequency pulse generated by the field divider is sent to the field sawtooth wave forming circuit. Under the action of the N201 15 pin external capacitor (C209), the internal field sawtooth wave forming circuit generates a field frequency sawtooth wave, which is amplified by the internal buffer. Output from 16 pins to the field output circuit of the subsequent stage. The N201 15 pin externally uses a capacitor as a field sawtooth to form a capacitor. The capacitance and its performance directly determine the linearity and amplitude of the field sawtooth.
2. The field output circuit field output circuit is composed of N602 (LA78040) and its peripheral circuits. The LA78040 includes a pump power supply circuit, an overheat protection circuit, and a field output release circuit. It has the advantages of low power consumption, high efficiency, and DC coupling. The field output circuit of the SF2170E color TV is shown in Figure 2.
The field frequency sawtooth wave output from the N201 16 pin is sent to the N602 (LA78040) 1 pin via R602, amplified by the internal differential amplifier, output from the N6025 pin, and then the field deflection coil V. DY and C606, R604, and finally grounded, generate a deflection current in the field deflection coil to make the electron beam scan vertically. C606 is the field output capacitor and R604 is the field sawtooth detection resistor. 
The external circuit of the N6017 pin is the non-inverting input of the N602 internal differential amplifier. The external R601 and R60lA divide the voltage of 5V to provide a fixed DC bias voltage for the 7 pin. The R609 and C607 connected to the 5 pin can effectively filter the line frequency component induced by the field deflection coil. VD602 is a clipping diode. R610 and C608 form a damping circuit, which can effectively eliminate the parasitic oscillation caused by the resonance of the field deflection coil and the distributed capacitance. R604, R607, C604, and R613 form an AC negative feedback circuit, which feeds back the AC sawtooth signal obtained on R604 to the N602 input pin 1 to improve the field scan linearity. R614, R613, R605, R604 form a DC negative feedback circuit. The DC component is taken out at the positive end of C606. After being divided by R614, R613, R605 and R604, it is also fed back to the N601 input terminal 1 to stabilize the N602 internal field output amplifier circuit. DC LT is in the state. The external C601 pin is a high frequency decoupling capacitor. The internal circuits of the VD601, C602 and N60236 pins together form a pump power supply boost supply circuit. R623 and R623A are connected to low level OV and high level 25V respectively. Adjust the resistance value appropriately to coarsely adjust the vertical position of the image on the screen, that is, change the center of the field.
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