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DA100 (50Hz) Chassis – Article for Television Magazine
Slave
There are two data lines that communicate with the slave processor located on the primary side of the
power supply. As this has to be isolated, communication is via two opto-couplers. IC703 is used to
send information to IC702 and opto-coupler IC704 is used for the return path.
power supply. As this has to be isolated, communication is via two opto-couplers. IC703 is used to
send information to IC702 and opto-coupler IC704 is used for the return path.
Reset In
Main system reset. This will operate each time the main switch mode powers supply starts. Reset is a
state change from low to high generated by IC1005.
state change from low to high generated by IC1005.
Reset Out (1)
IC801 reset (low). If IC801 is not reset then the line oscillator will not function. Reset out (1) will only
occur after reset in.
occur after reset in.
Reset Out (2)
Resets all other areas of this television, this will only occur after reset out (1). Note that the reset
for the teletext IC is inverted.
for the teletext IC is inverted.
Reset Operation
It can be seen from the diagram below that all of the reset signals are a change in state, either from
low to high or high to low. The order of events is as shown, supply, reset in, reset out (1), reset out (2).
The horizontal oscillator will not start until reset out (1) has occurred. Even though IC801 generates
the horizontal drive signal, it will not be present until the mute has been released (HOUT=0V)
low to high or high to low. The order of events is as shown, supply, reset in, reset out (1), reset out (2).
The horizontal oscillator will not start until reset out (1) has occurred. Even though IC801 generates
the horizontal drive signal, it will not be present until the mute has been released (HOUT=0V)
Figure 51: Reset Timing
Page 51 of 80
Sharp Electronics (UK) Limited - March 2003
Revision 2
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