Sharp 76FW-53H (serv.man13) Service Manual ▷ View online
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 18
R
ESET
It can be seen from the diagram below that all of the reset signals are a change in state, either form
low to high or high to low. The order of events is as shown, supply, reset in, reset out (1), Reset out
(2). The line oscillator will not start until reset out (1) has occurred and the HOUT pulse = zero
low to high or high to low. The order of events is as shown, supply, reset in, reset out (1), Reset out
(2). The line oscillator will not start until reset out (1) has occurred and the HOUT pulse = zero
3v3
Reset in
Reset out (1)
Reset out (2)
MegaText Reset
From Reset out (2)
From Reset out (2)
Low
Low
Low
Low
HOUT
IC1001 pin 57
IC1001 pin 57
Low
Low
Low
Power Supply
Start
Start
Line Drive
Start
Start
PROT
IC1001 pin 95
IC1001 pin 95
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 19
PROTECTION
M
ICROPROCESSOR
A
UDIO
O
UTPUT
The outputs from all of the audio output stages are fed to the base of Q303 and Q304. C377 and
R361 form an averaging circuit. Since the audio signals are basically sine waves the d.c. voltage at
the base of these transistors
should be zero. If this base
voltage was to increase in a
positive direction Q303 will turn
on, removing the biased from
IC1001 pin 95, and the CTV will
switch to standby.
R361 form an averaging circuit. Since the audio signals are basically sine waves the d.c. voltage at
the base of these transistors
should be zero. If this base
voltage was to increase in a
positive direction Q303 will turn
on, removing the biased from
IC1001 pin 95, and the CTV will
switch to standby.
The same is true if the base
voltage increase negatively, this
time Q304 will turn on, turning
on Q302 causing IC1001 pin 95
to fall and the CTV will again
switch two standby.
voltage increase negatively, this
time Q304 will turn on, turning
on Q302 causing IC1001 pin 95
to fall and the CTV will again
switch two standby.
B
EAM
C
URRENT
If the beam current increase D622 will conduct, turning on Q606 which removes the bias from IC1001
pin 95. The CTV will switch to standby
pin 95. The CTV will switch to standby
H
ORIZONTAL
M
UTE
During the boot sequence the horizontal drive is inhibited by the HOUT signal from the
microprocessor (IC1001 pin 57).
microprocessor (IC1001 pin 57).
Its function is to remove the line drive by turning on Q607, thus placing short between the horizontal
drive signal and ground, at the same time this HOUT pulse will cause the audio mute circuits to
activate, preventing any noise from the speakers.
drive signal and ground, at the same time this HOUT pulse will cause the audio mute circuits to
activate, preventing any noise from the speakers.
Additionally HOUT signal will occur when the microprocessor can not communicate with the other
devices connected to the I²C buses
devices connected to the I²C buses
Protection
IC1001 pin 95
IC1001 pin 95
-16v
Audio
+5v
Q303
R1021
4k7
4k7
Q302
Q304
D301
R361
10k
10k
C377
10
10
R360
10k
10k
Q606
D622
27v
27v
R615
5k6
5k6
C644
2200
2200
ABL
(T601 pin 8)
(T601 pin 8)
1
2
3
100nF
5v
C1028
IC1005
Main
Reset
Reset
HOUT
IC1001 pin 57
IC1001 pin 57
3v3
Mute
Q1004
R1047
10k
10k
R1049
10k
10k
R1044
10k
10k
R1005
4k7
4k7
C1033
68nF
68nF
3v3
D1009
R626
4k7
4k7
Q602
Line Drive
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 20
V
IDEO
/S
YNC
P
ROCESSOR
The video/sync processor (IC801) contains protection circuit that can monitor the scanning circuits
operation.
operation.
S
AFETY
IC801 pin 12, EHT is calculated by measuring the rectified horizontal fly-back pulse. D615 and C617
are the rectifier components, and D617 limits the bias at pin 12 (sets normal conditions, >1v) There
are two thresholds once the first threshold has been met the RGB drives are blanked, if the d.c.
voltage continues to rise and passes the second threshold, then the horizontal drive is stopped.
are the rectifier components, and D617 limits the bias at pin 12 (sets normal conditions, >1v) There
are two thresholds once the first threshold has been met the RGB drives are blanked, if the d.c.
voltage continues to rise and passes the second threshold, then the horizontal drive is stopped.
V
PROT
This pin is monitoring the operation of the vertical output stage. The vertical fly-back pulses are
applied to pin 11. If the negative edge of this signal cannot be detected then the RGB drives are
blanked.
applied to pin 11. If the negative edge of this signal cannot be detected then the RGB drives are
blanked.
+5v
Q608
Safety
HFB
HFB
D618
4v7
4v7
C643
10nF
10nF
R644
220
220
C617
100nF
100nF
D617
24v
24v
D615
R615
1k
1k
R620
1k
1k
IC801
12
13
11
Vprot
Colour Television – DA100/DW100 Chassis
Sharp Electronics (UK) Ltd
Technical Support
September 99
Page 21
A V Link
This CTV chassis has the capability of directly controlling a VCR via the SCART socket or the VCR
controlling the CTV. In either chase the VCR must be compatible with the ‘A V Link’ system, also
during the installation of the CTV and VCR you will decide whether it is the CTV or VCR which has
overall control.
This CTV chassis has the capability of directly controlling a VCR via the SCART socket or the VCR
controlling the CTV. In either chase the VCR must be compatible with the ‘A V Link’ system, also
during the installation of the CTV and VCR you will decide whether it is the CTV or VCR which has
overall control.
Data from the CTV to VCR is from IC1001 pin 16 via Q1005 and is outputted from pin 10 either AV-1
or RGB SCART sockets. Data from VCR is from the same SCART connection but this time it is fed
into IC1001 pin 92 via D1003. D411 provides protection from excess voltage being applied to the
SCART sockets.
or RGB SCART sockets. Data from VCR is from the same SCART connection but this time it is fed
into IC1001 pin 92 via D1003. D411 provides protection from excess voltage being applied to the
SCART sockets.
In addition to this data is outputted at AV-1 SCART pin 12, this data is intended to be read by a
computer, enhancing fault finding procedures. Currently this system is still being developed, more
details will be given when the software and interface becomes available.
computer, enhancing fault finding procedures. Currently this system is still being developed, more
details will be given when the software and interface becomes available.
IC1001
92
16
21
R1023
220
220
R1033
10k
10k
+5v
R1032
27k
27k
R1025
10k
10k
+5v
R1035
4k7
4k7
D411
5v6
5v6
Q1005
D1003
AV-1 Scart
pin 12
pin 12
AV-1 Scart
pin 10
pin 10
RGB Scart
pin 10
pin 10
Service Data
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