Sharp 66FW-54H (serv.man7) Service Manual ▷ View online
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 4
N
L
T702
IC708
R763
100
100
POR701
Q714
From IC702
pin 14
pin 14
From T701
pin15
pin15
D727
R762
220
220
R768
220
220
C702
10nF
10nF
Degause
Coils
Coils
D728
4v7
4v7
D
EGAUSS
C
IRCUIT
This circuit is configured to ensure that the degauss circuit will not operated unless the switch mode
power supply is operating and IC702 pin 14 = low.
power supply is operating and IC702 pin 14 = low.
A positive bias is applied to the emitter of Q714 from T701 pin 15 (rectified by D727 and limited by
D728). Via the opto-coupler; IC708. Since Q714 is a pnp device once the base is taken low compared
to the emitter, Q714 will turn on allowing current to flow through IC708 (LED Section), turning on the
triac T702, allowing current to flow through the degauss coils.
D728). Via the opto-coupler; IC708. Since Q714 is a pnp device once the base is taken low compared
to the emitter, Q714 will turn on allowing current to flow through IC708 (LED Section), turning on the
triac T702, allowing current to flow through the degauss coils.
Current will continue to flow through the degauss coils until either the PTC (POR701) has increased in
value sufficiently to cut off the current flow, or IC702 pin 14 goes high, turning of Q714, preventing
current flow through IC708, turning the triac T702 off.
value sufficiently to cut off the current flow, or IC702 pin 14 goes high, turning of Q714, preventing
current flow through IC708, turning the triac T702 off.
Since the default condition for IC702 = low, it can be seen that the degauss circuit should now operate
each time the CTV is turned on from the main on/off switch or switched from standby to normal
operation. Whether the main processor has set up communication with the slave processor or not.
each time the CTV is turned on from the main on/off switch or switched from standby to normal
operation. Whether the main processor has set up communication with the slave processor or not.
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 5
5
V
R
EGULATOR
This is another new circuit, but depending on whether you are dealing with the DA100 (4:3) chassis or
DW100 (16:9) chassis will determine the exact circuit.
DW100 (16:9) chassis will determine the exact circuit.
DA100 (59ESD7H
AND
66ESD7H) 4:3
CHASSIS
The FET Q704 is a series regulator producing 5v, which is controlled by Q713. A voltage is fed-back
from the output of Q704 (junction of L705 and C723) which will control the conduction of a variable
zener diode (IC707). D723, Q705 and Q706 provide protection against excessive supply voltage.
from the output of Q704 (junction of L705 and C723) which will control the conduction of a variable
zener diode (IC707). D723, Q705 and Q706 provide protection against excessive supply voltage.
D722
D714
IC707
D723
2v7
2v7
Q705
Q706
Q704
+5v
+16v
From T701
pin 1
pin 1
Q713
L705
C723
2200
2200
C734
470
470
C721
470
470
R760
4k7
4k7
R729
4k7
4k7
R757
2k2
2k2
R726
22
22
R706
8k2
8k2
R710
2k2
2k2
R707
1k5
1k5
R725
10k
10k
C722
10nF
10nF
C735
150pF
150pF
R731
10k
10k
R756
10k
10k
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 6
DW100 (56FW53H
TO
6FW54H) 16:9
CHASSIS
For models using the DW100 chassis this regulator circuit has been replaced by an integrated circuit
(L4978D).
(L4978D).
This DC-DC converter will operate from a supply between 8v to 55v and produces an output voltage
of between 3v3 and 50v depending on the value of R747 (5v output R747 = 2k7). C741 connected to
pin 3 provides a soft-start routine. If pin 3 is held low then the device will not operate. The frequency
of the internal oscillator is fixed by the value of R706 and C735. Over-current and over-voltage
protection is incorporated into the design of this device.
of between 3v3 and 50v depending on the value of R747 (5v output R747 = 2k7). C741 connected to
pin 3 provides a soft-start routine. If pin 3 is held low then the device will not operate. The frequency
of the internal oscillator is fixed by the value of R706 and C735. Over-current and over-voltage
protection is incorporated into the design of this device.
D722
T701 pin 1
4
11
3
2
14
5,6
13
C721
470
470
C743
100nF
100nF
C735
2n7
2n7
R706
20k
20k
R748
4k7
4k7
IC707
C722
100nF
100nF
L705
D714
C742
68nF
68nF
R747
2k7
2k7
+5v
C741
100nF
100nF
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 7
CLASS D OUTPUT STAGES
The class ‘D’ output stages that Sharp Electronics have used since the introduction of the CS chassis
are now incorporated into a specially design integrated circuit (TDA7480 = 10w output power,
TDA7481 = 15w output power and TDA7482 = 25w output power). These devices are ideal for use
with TV Audio & Field output stages where high efficiency (low energy use) is required.
are now incorporated into a specially design integrated circuit (TDA7480 = 10w output power,
TDA7481 = 15w output power and TDA7482 = 25w output power). These devices are ideal for use
with TV Audio & Field output stages where high efficiency (low energy use) is required.
Sharp Electronics are currently using the TDA7480 for Audio and Frame outputs and the TDA7481 to
drive the sub-woofer.
drive the sub-woofer.
T
DA
7480 P
IN
F
UNCTIONS
Pin No.
Name
Function
1
2
3
4
5
6
7
8
9
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
11
12
13
14
15
16
17
18
19
20
-V
CC
-V
CC
-V
CC
OUT
BOOTDIODE
BOOT
NC
FEEDCAP
FREQUENCY
SGN-GND
IN
ST-BY-MUTE
NC
+V
BOOTDIODE
BOOT
NC
FEEDCAP
FREQUENCY
SGN-GND
IN
ST-BY-MUTE
NC
+V
CC
SIGN
VREG
+V
+V
CC
POW
-V
CC
-V
CC
-V
CC
-V
CC
NEGATIVE SUPPLY.
NEGATIVE SUPPLY.
NEGATIVE SUPPLY.
PWM OUTPUT
BOOTSTRAP DIODE ANODE
BOOTSTRAP CAPACITOR
NOT CONNECTED
FEEDBACK INTEGRATING CAPACITANCE
SETTING FREQUENCY RESISTOR
SIGNAL GROUND
INPUT
ST-BY/ MUTE CONTROL PIN
NOT CONNECTED
POSITIVE SIGNAL SUPPLY
10V INTERNAL REGULATOR
POSITIVE POWER SUPPLY
NEGATIVE SUPPLY (De-coupled by 100nF)
NEGATIVE SUPPLY
NEGATIVE SUPPLY
NEGATIVE SUPPLY
NEGATIVE SUPPLY.
NEGATIVE SUPPLY.
PWM OUTPUT
BOOTSTRAP DIODE ANODE
BOOTSTRAP CAPACITOR
NOT CONNECTED
FEEDBACK INTEGRATING CAPACITANCE
SETTING FREQUENCY RESISTOR
SIGNAL GROUND
INPUT
ST-BY/ MUTE CONTROL PIN
NOT CONNECTED
POSITIVE SIGNAL SUPPLY
10V INTERNAL REGULATOR
POSITIVE POWER SUPPLY
NEGATIVE SUPPLY (De-coupled by 100nF)
NEGATIVE SUPPLY
NEGATIVE SUPPLY
NEGATIVE SUPPLY
P
IN
9 – F
REQUENCY
The external components on this pin will determine the base frequency of the PWM section of this IC.
Remember for the audio circuit the frequency will vary from the base frequency by the bandwidth of
the audio signal (20kHz).
Remember for the audio circuit the frequency will vary from the base frequency by the bandwidth of
the audio signal (20kHz).
P
IN
12 – M
UTE
/S
TANDBY FUNCTION
The voltage at pin 12 will determine the working condition of this device. A voltage of less than 0.8v
will tell the device to switch to standby, where a voltage between 1.8v to 2.5v will result in the output
being attenuated between 60 to 80 dB. For normal operation the voltage at pin 12 should be greater
than 4v.
will tell the device to switch to standby, where a voltage between 1.8v to 2.5v will result in the output
being attenuated between 60 to 80 dB. For normal operation the voltage at pin 12 should be greater
than 4v.
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