KENWOOD RCV7
Instrukcja Serwisowa

RC-V7
CIRCUIT DESCRIPTION
Panel Section (LCD ASSY: B38-0772-65)
The panel section controls serial communications with the main unit control section, the key input circuit, the display circuit, and the dimmer circuit through the microprocessor (IC4).

� Display circuit
Display section is a 152x45-dot full-dot matrix LCD controlled by two LCD. As shown in Figure 1, the master IC (IC5) side is connected to 32 common dots and 80 segment dots and the slave IC (IC6) side is connected to 13 common dots and 72 segment dots. The LCD drive voltage is obtained by raising the power supply voltage (5V) within the IC. Also, the contrast level (LEBEL8) for resetting is adjusted with R19 to be optimum.

� Serial communications circuit
A buffer is inserted in order to protect the microprocessor ports.

� Key input circuit
There is one microprocessor port for each panel section key. The PSW key is pulled down and the other keys are pulled up with software within the microprocessor. The rotary encoder is input directly to the microprocessor.

32 COM

LCD 152 X 45(dot) 80 SEG LCD Driver IC 5 72 SEG LCD Driver IC 6 13 COM

Microprocessor IC4

Fig. 1 Display circuit
9V LED1 R57 LED2 LED3 LED4

� Dimmer circuit
The dimmer circuit switches the lamp brightness to one of four levels or OFF. (See Table 1.) The current flowing to the LEDs is varied by selecting resistors from R55 to R58. Dimmer level 1 2 3 4 OFF P60 H L L L L P61 L H L L L P62 L L H L L P63 L L L H L
P62 IC4 Microprocessor

R58

P60 Q13 P61 Q12

Table 1 Port logic

Q11 P63 Q10

Fig. 2 Dimmer circuit 2

R56

R55