High-Voltagecircuit; Vertical Deflection Circuit; Dynamic Focus Circuit - Sony Multiscan GDM-2036S Service Manual

GOM-2036S
C221, C222, C223, C224 and C225 are capacitors to make the
S-shaped correction. Furthennore, as the value must be
changed in accordance with the horizontal frequency, it
chooses the appropriate combinations by 0205, 0207, 0209
and 0211.
The on/off relations between the frequency and the transistors
are as shown in Table 3-2.
RANGE
1 2 3 4 5 6 7
30 30.8 31.8 32.6 33.4 34.4 35.6
8 9 10 11 12 13 14 15 16
37.0 38.8 41.0 43.4 46.0 49.2 53.4 58.6 65.8
fH (kHz)
-30.7 -31.7 -32.5 -33.3 -34.3 -35.5 -36.9 -38.7 -40.9 -43.3 -45.9 -49.1 -53.3 -58.5 -65.7 -71.0
Q205
ON OFF ON OFF ON OFF ON OFF
Q207
ON OFF ON OFF
Q209
ONO OFF
Q211 ON
Q405
ON
Q407
ON
Table 3-2.
3-4·3. Hlgh·voltage CIRCUIT
Horizontal drive transistors 0203 and T201 (HDT) drive high
voltage output transistor 0401 along with the H-OUT at
0204. Accelerated diodes D401 and D402 are connected in
series to the base of 0401. After 0204 turns off, the diodes
continue to operate, causing 0401 to tum off. This protects
the horizontal deflection system from being affected by the
deflection by the high-voltage load.
The series capacitors C401, C402, and C422 are connected to
the collector at 0401 and function as the resonate components
of the flyback pulse.
The total value is selected by shorting the two capacitors with
0405 and 0407 in order to get a enough peak voltage for the
variable frequency.
The status of the two transistors are shown in Table 3-2.
The B+ voltage is supplied via lAOl. Six rectifier diodes are
built into the secondary side of the FBT and the voltage at the
secondary level is supplied to the focus pack to remove focus
voltage and the G2 voltage.
A high voltage olltput is built into the FBT and a high voltage
capacitor and high-voltage resistor are installed between each
grounding and where they perfonn high voltage rectification
and high voltage detection.
The high voltage output in the FBT is scaled down to 1/3000
by the high voltage resistor and then supplied to pin @ of
IC302 (1/2) where it is compared with reference voltage (9.00
V). Next, the differential voltage is amplified and input to pin
ON OFF ON OFF ON OFF ON OFF
ON OFF ON OFF
ON OFF
OFF
OFF
OFF
@ of IC202 (1/2). The H. SAW wave input to pin @ of IC202
and subjected to PWM by the comparater. The pulse
generated at pin
CD
of IC202 (1/2) switches 0402 (a damper
diode with built-in FET) via 0403 and 0404.
3-4-4. Vertical deflection circuit
The V. SIZE signal sent from the N board is input by the
vertical deflection circuit structured of 0301, 0307 and
IC304, while the vertical deflection yoke is driven by the
SEPP circuit structured at 0303 to 0306. 0302 which
functions as the power source switch to the vertical output
circuit from the B+ source, is turned on during vertical
flyback by the pulse output from pin @ of IClOl on the N
board.
3-4-5. Dynamic Focus Circuit
H. parabola and H. SAW are mixed and amplified by ICI02
(1/2), and the bottom of the wavefonn is rounded by D602.
It is amplified to approx. 700V H. parabola by the cascade
amp. at 0602 and 0605. 0603 and Q607 consist push pull
amp. and the output signal is fed back to 0605 and 0607 from
the detector R623.
The V. parabola output from the N board is amplified to V.
parabola of approx. 300V by 0604 and this clamps the H.
parabola with D601. As a result, dynamic focus wavefonns
which are composed where the V. parabola overlaps with the
H. parabola are fonned.
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