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1.2 Horizontal deflection block
The operating principle of the horizontal deflection circuit is given below.
The Q502 operates as horizontal output, and the D503 as the dumper diode.
As shown in Fig. 5, the horizontal output transistor Q502 turns to ON/OFF by means of the drive pulse in
pin 25 of IC601 in substrate DEFL-SUB through the drive transformer T501, drive transistor Q501, or
Q560, Q561, Q562, etc.
The deflection current Idy during Q502 ON gets increased to the maximum level Ip according to the
equation shown below:
Idy = (Vcc/Ldy) x Ton
The maximum Ip is approximately 8A at full scan when fh = 106k.
Here;
Vcc: Output voltage of Q504
Ldy: Parallel value of the Lh value of DY (=62
µ
H) and the horizontal output transformer
(=5mH)
TON: The ON time of Q502
When the drive pulse has negative polarity, Q502 turns OFF and Idy starts flowing to charge C506 until
the collector voltage reaches the maximum level Vcp.
Vcp = Vccx{1 + (
π
/2)x(Ts/Tr)}
With the maximum Vcp attained, the charges accumulated in C506 flow into DY as the discharge current.
This charge/discharge current is called retrace time, and is expressed by the equation given below.
Tr =
π
(Ldy•Cr) * Cr = C506 value
In the present model, the retrace time is set to approx. 1.8
µ
s.
Ts is called trace time, and is expressed by the equation given below with the horizontal cycle as T.
T = Ts + Tr
With Vcp = 0, the dumper diode D503 turns ON and Idy gets decreased from –Ip to 0 ampere. Since
Q502 ON time and dumper diode ON time are set to overlap at 0 ampere point of Idy, the crossover
distortion is prevented from occurring at 0 ampere point of Idy.
The D503 causes the transient current to flow in the high-speed dumper diode.
The horizontal output transformer T502, connected in parallel to the deflection yoke, operates as a choke
coil. Figs. 6 and 7 show the image of circuit operation and the waveforms in actual machine.
Summary of Contents for MultiSync FP1355 FP1355 FP1355
Page 23: ...1 17 Q502 Q502 Damper diode Current waveform fh 106k ...
Page 25: ...1 19 Q502 Q502 Damper diode Current waveform Q502 Ic Q502 Vce ...
Page 58: ...1 52 Figure 25 IC211 MC13289ASP block diagram ...
Page 63: ...1 57 Figure 30 IC212 XC3824P2 block diagram ...
Page 65: ...1 59 1 11 Wave form of main circuit voltage ...
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Page 120: ...MultiSync FP1355 User s Manual ...
Page 144: ... VSP C0464 REVISE 2 ...
Page 166: ...Fig 2 BEZEL LOGO VSP C0464 COLOR OF LETTERING Kingfisher Blue 6704 11 5 24 5 66 ...
Page 169: ...VSP C0464 Fig 5 1 PRINTING SPECIFICATION OF CARTON BOX North America ...
Page 170: ...VSP C0464 Fig 5 2 PRINTING SPECIFICATION OF CARTON BOX Europe ...
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