The second sound intermediate frequency signal SIF2 obtained via the internal phase-
locked decoding of TMPA8899-XXXX passes the limiting amplifier and the frequency
discriminator to get an audio signal, which is output by Pin 28 and Pin 29. The two audio
signals are sent to Pin 6 and Pin 8 of N701 respectively for audio power amplification,
and the amplified audio signal is output to drive the speaker.
4. External AV input processing circuit:
The external audio and video 1 (V1, L1 and R1) are input from Pin 5, Pin 12 and Pin 2 of
N801 (TC4053) respectively; The external audio and video 2 (V2, L2 and R2) are input
from Pin 3, Pin 13 and Pin 1 of N801 (TC4053) respectively; The switching action of
N801 (TC4053) is controlled by control level output by Pin 56 of N103. After switching,
video is output by Pin 4 of N801 (TC4053) and input to TMPA8899-XXXX via Pin 24 of
N103 for internal processing; audio is output by Pin 14 and Pin 15 of N801 (TC4053)
and input to TMPA8899-XXXX via Pin 24 of N103 for internal processing.
5. Horizontal scanning circuit:
The main chip TMPA8899-XXXX is separated internally in synchronization and consists
of VCO oscillation circuit, horizontal frequency dividing circuit, AFC circuit and horizontal
output driving circuit. The horizontal actuating signal is output from Pin 13 of TMPA8873-
XXXX, amplified at driver stage via V431(2SC2383) and then amplified at output stage
via V432. T431 is a horizontal driving transformer, and C432, R433 and C433 are mainly
used to absorb the peak pulse on the electrode when V431 interrupts suddenly to
prevent V431 from breakdown. The horizontal tube V432 (2SC5296) is equipped with
delayed diode, so pay attention to substitution during maintenance. C435, C437 and
C436 are horizontal resonance capacitor, and VD435 and VD436 are delayed diodes. In
the case of horizontal wide, horizontal narrow and burning of horizontal pipe, such units
should be examined. L441 is a horizontal linear inductance and C441 is S corrective
capacitor.
T471 is a horizontal resonance transformer. The DC voltage of +110V (21”)+130V (29”)
is input from Pin 4 of T471. The horizontal resonance pulse output by Pin 8 is divided
into two lines: pulse on one line is directly supplied to filament of the kinescope to
provide 6.3V effective voltage; pulse on the other line passes R405 for voltage reduction
