Mitsubishi Electronics WS-65513, WS-48613 Serial Data Lines, ΜPC Parallel Inputs, AC-OFF Input

Note that the output of the Wide Band Preamp (IR-IN) is also directed to the SYS-5 µPC. This connection was not used in the V19 and V21. It enables the Learn- ing feature. The signals from the units Remote are memo- rized by the SYS-5 circuitry.

Serial Data Lines

Figure 4-4shows the Serial Data lines and indicates what circuits they control. ICs IC7B00~IC7B03 are level shift ICs, changing the 3.3V data and clock lines from IC7A00 to 5V lines.

In previous sets the TV Control circuitry used two E2PROM Memory ICs, one on the PCB-SIGNAL and one on the PCB-TERMINAL. Due to the changes in design only one E2PROM is required, and for factory alignment purposes it is located on PCB-TERMINAL.

In the V23 the DTV Tuner and Modulator are separate from the DM Module. The DTV Tuner is controlled by the TDAT and TCLK lines from the DM Module. The DM Module also controls the MLink (DVI) circuitry, through the DVI-RXD and DVI-TXD lines.

Figure 4-4also shows that the DM Module receives and processes the signals from the Card Reader.

µPC Parallel Inputs

The parallel inputs to the µPC are status inputs or sig- nals inputs required for control purposes.

AC-OFF Input

Informs the µPC if AC Power is lost. The monitoring circuit is shown in Figure 4-5.Samples of the input AC are applied to the base of Q9A10. D9A16 removes the negative half of the sine waves. The remaining posi- tive half cycles keep Q9A10 conducting. With Q9A10 conducting PC9A10 conducts, turning Q7A20 On. The conduction of Q7A20 holds the AC-OFF input to IC7A00 Low.

If AC power is lost, Q9A10, PC9A10 and Q7A20 all quit conducting, allowing pin 20 of IC7A00 to go High. This informs the Control circuitry power has been lost. The µPC responds by rapidly storing all user program- ming and service adjustments to memory. It also out- puts a High on the Power Good line, informing the DM of the power loss.

4-5