AVK200 home theater amplifier and maintenance 02

(2) Operation display circuit
    The operation input circuit of the machine includes two parts: keying circuit and infrared remote control circuit. Each operation button is set on
the 3X7 matrix circuit composed of keying input lines. The ④～⑩ pins of 01N1 output 7 button scanning signals (P2～P8), which are sent to 7 groups of operations through 7 isolation
diodes 1VD14-^- 1VD20. Scan lines. Each group of scan lines is equipped with 3 keys, which can generate 3 sets of key command signals
(KO ~ K2). When a key is effectively pressed, the key commands are input from the @ ~ ◎ pins of 1N2 respectively, and are identified and
processed . Output various control signals to control the controlled circuit. The control port
    is connected to an 8-bit output latch shift register (74HC595), which is used as a 1N2 interface line expansion
. 1N3 (HS0038A) receives various operating instructions from the infrared remote control and then transmits them to 1NZ to realize remote
control operation.
    The memory TA24COIA memorizes the working status of the machine (that is, various data sent by 1N2). When the machine loses power due to shutdown or other reasons, the working status of the machine has been recorded and saved, so that the machine can automatically recover
the next time it is turned on.
to the previous operating status, so that the user does not have to reset the machine working status.
    While 1N2 outputs operation command data to each functional part, it processes the corresponding working mode and related information into pulse
data and sends it to 1N1 (UCN5818AF). 1N1 outputs the corresponding level signal to control the content display of the VFD.