Read Sharp 76FW-53H (serv.man13) Service Manual online
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 16
E
AST
W
EST
C
IRCUIT
In addition to the normal function of an East West correction circuit used with 4:3, 110° CRT, with a
wide screen CTV correction has to be allowed for the different types of scanning modes.
wide screen CTV correction has to be allowed for the different types of scanning modes.
16:9 CTV generally has three scanning modes, 4:3, 14:9 and 16:9, additionally the 16:9 scanning
modes has three variants, Full, Panama and Cinema. Full mode is used to stretch a picture which is in
4:3 format and contains fast moving action (motor racing), therefore, it does not matter if the line
linearity is not constant across the screen. Panama is similar to full mode but this time the action is
slow or even stationary (news programs), therefore, your eye would pickup on any variation in
linearity. To overcome this the linearity in the centre of the screen is kept constant and the edges of
the picture are stretched to fill the screen. Cinema mode is intended for use with pictures that are in
true 16:9 format.
modes has three variants, Full, Panama and Cinema. Full mode is used to stretch a picture which is in
4:3 format and contains fast moving action (motor racing), therefore, it does not matter if the line
linearity is not constant across the screen. Panama is similar to full mode but this time the action is
slow or even stationary (news programs), therefore, your eye would pickup on any variation in
linearity. To overcome this the linearity in the centre of the screen is kept constant and the edges of
the picture are stretched to fill the screen. Cinema mode is intended for use with pictures that are in
true 16:9 format.
C
IRCUIT
D
ESCRIPTION
IC503 is a switching amplifier with integrated line pulses being fed to one input from the line driver
circuit via Q501 and an East West parabolic signal from IC801 to the other input. This will produce a
PWM signal running at line frequency and the width of the pulses will be determine by the East West
parabolic signal.
circuit via Q501 and an East West parabolic signal from IC801 to the other input. This will produce a
PWM signal running at line frequency and the width of the pulses will be determine by the East West
parabolic signal.
This signal is then passed a driver circuit (Q506, class ‘d’ biased), low passed filtered (L603, C610) to
the diode modulator (D603 and D604). Additionally from L603 the signal is fed to one end of a centre
tap coil (L604) via C611. The other of L604 is connected to ground with the centre tap connected to
the line linearity circuit. Therefore the line linearity can now be adjusted by the East West Parabolic
signal.
the diode modulator (D603 and D604). Additionally from L603 the signal is fed to one end of a centre
tap coil (L604) via C611. The other of L604 is connected to ground with the centre tap connected to
the line linearity circuit. Therefore the line linearity can now be adjusted by the East West Parabolic
signal.
Q601 (c)
Scan Coils
+5v
Diode Modulator
L604
RA611
3k3
3k3
L605
C619
2.2
2.2
C620
2.2
2.2
C613
560nF
560nF
D613
R613
2k2
2k2
L603
C611
1
1
D503
R610
1
1
C518
10pF
10pF
Q506
R525
10k
10k
R524
1k
1k
R527
1k
1k
+
-
EW Drive
Line
Drive
Drive
+150v
+5v
D506
R519
100k
100k
Q501
C514
47nF
47nF
R525
5k6
5k6
R555
100k
100k
R556
10k
10k
IC503
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