Sharp 66FW-54H (serv.man7) Service Manual ▷ View online
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For models using the DW100 chassis this regulator circuit has been replaced by an integrated circuit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.
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 8
A
UDIO
O
UTPUT
At switch on C362 is discharged holding IC301, pin 12 low preventing any output from IC301 until
supply has been established. Once supply has been established and IC301, pin 12 is greater than 4v
then the IC301 will start to oscillate, producing a PWM signal with a frequency and a mark space ratio
which is dependant on the input signal at pin 11. L352 and C361 form a low pass filter for conversion
of the PWM signal into an analogue signal to drive the loudspeaker. A proportion of this drive signal is
fed into an averaging circuit via R358 as a protection signal i.e. if the average of the signal at the
junction of R358 and L352 is not zero then the software will switch the CTV to standby mode.
supply has been established. Once supply has been established and IC301, pin 12 is greater than 4v
then the IC301 will start to oscillate, producing a PWM signal with a frequency and a mark space ratio
which is dependant on the input signal at pin 11. L352 and C361 form a low pass filter for conversion
of the PWM signal into an analogue signal to drive the loudspeaker. A proportion of this drive signal is
fed into an averaging circuit via R358 as a protection signal i.e. if the average of the signal at the
junction of R358 and L352 is not zero then the software will switch the CTV to standby mode.
M
UTE
During system reset or when the ‘Line Mute (HOUT)’ is present, the audio outputs will be muted due
to an increase in Q305 base bias, turning it on.
to an increase in Q305 base bias, turning it on.
The circuit description/diagram for this mute signal is shown on page 19.
-
+
PRE
-
+
PWM
16
14
7,13
12
6
4
5
15
17
1,2,3,18,19,20
9
10
8
11
N.C
Vcc pow
Vcc sign
Boot
Boot Diode
Vref
-Vcc
-Vcc
Freq
Sign-GND
St-By/Mute
Feedcap
TDA7480
Mute
R362
4k7
4k7
Q305
C362
2.2
2.2
Input
R372
10k
10k
C356
15nF
15nF
C357
1nF
1nF
R375
47k
47k
C359
4n7
4n7
C354
100pf
100pf
R352
12k
12k
-16v
C358
100nF
100nF
C360
560pF
560pF
R353
150
150
C361
470nF
470nF
Protection
C353
100nF
100nF
+16v
R351
27k
27k
R358
100k
100k
L352
Left Channel
200kHz
IC301
R350
10k
10k
+5v
Click on the first or last page to see other 66FW-54H (serv.man7) service manuals if exist.