Service manual

CA-16
CA CIRCUIT DESCRIPTIONS
Deflection Processing
The last portion of the video processor to be discussed is the deflection section. This is the part of the IC
from which the vertical and horizontal deflection signals are derived. A critical power supply to this section
is the +9VSW which feeds pin 26. Pin 24 emits the V-Ramp signal, from which both vertical sync for the
microprocessor and vertical drive for the vertical amplifier are developed. Refer to Q6002 in the micropro-
cessor circuit for this process. Horizontal drive comes from pin 32. This ultimately drives the horizontal
output transistor, which provides both horizontal deflection and power for the sweep transformer. Pin 31
provides the sync pulse output to IC6000. This signal is really the horizontal sync pulse separated from the
rest of the video signal. It allows the microprocessor to determine whether or not the receiver has a valid
signal. The flyback pulse is input to pin 30, thus allowing sweep feedback to the video processors deflec-
tion section.
29
30
31
32
33
34
3522
23
24
25
26
27
28
VPULSE
NFB
VRAMP
VSEPFIL
HVCC
SCL
SDA
DGND
32FH
HAFC
H-OUT
H-SYNC
FLYBACK
SHUTDOWN
ICX2200
C2213M C2214M R2224MC2212M
PROV
R2223
R2220
C2211M
PROV
C2208
C2209
C2210M
R2216
+9VSW
R2212M
VRAMP
CLOCK
DATA
R2225M
C2215M
D2201
R2226
C2554 PROV
CR2202
R2231M
R2229M
C2217M
C2216
R2227M
FLYBACK
SHUTDOWN
H-SYNC
H-DRIVE
<<Figure CA-14>>
High-Voltage Protection
The last terminal of note here is pin 29, the x-ray protection/shutdown pin. If the potential at this pin rises
above +3.5 volts DC, the video processor will automatically clamp the horizontal output signal, shutting
down the receiver. In the event that this occurs, the microprocessor will have to be reset before the televi-
sion can be powered up again. Voltage at pin 29 is based on the voltage output from the flyback. High
voltage shutdown will correspond with an over-voltage in the picture tube, which could otherwise begin to
emit x-radiation.