JVC XV-1000BK, Service Manual

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4. Microcomputer Volume
Processing of Each Microcomputer
* IC601 System microcomputer (sub-microcomputer)
After powering on, this microcomputer is continuously activated to control keys and remote control
signals.
According to key operations or remote control signals, it controls (turns on/off) the power for
LSIs including IC401 (main microcomputer) and the audio/video output circuit.
It also controls the resetting of the main microcomputer, FL driver IC (IC831) for FL display, and
various LED displays.
* IC401 Main microcomputer
This microcomputer controls a group of LSIs of servo and signal processing sections according to
commands from the system microcomputer.
After receiving time information from the signal processing section, it transmits the information
together with the status to the system microcomputer.
It controls the resetting of the LSIs of the servo and signal processing sections.
It has IC405 (1Mbit ROM) as an external ROM.
Normal Starting Conditions
* IC601 System microcomputer
(1) +5V must be applied to "72" and "73".
(2) Oscillators of "31" and "32" must be oscillating correctly.
(3) Input to "16" (RESET) must be at +5V (reset cancel).
If above (1) to (3) are not satisfied when the P.STANDBY indicating lamp does not light at
power-on, IC601 may be defective.
* IC401 Main microcomputer
(1) +5V must be applied to "8", "13" and "42".
(2) Clock signal (13.5MHz) must be input to "14" from IC351 (DEM/ECC LSI).
(3) Input to "1" (CPURST) must be at +5V (reset cancel).
(4) Communication line with IC601 ("38", "39", "43", "44" and "45") and that with IC405 (external ROM)
("17" to "32", "2", "3", "4", "6", "49") must work normally.
If above (1) to (3) are not satisfied when the P.STANDBY indicating lamp goes out but FL does not
light when the POWER switch is turned on, IC401, IC601 or IC405 may be defective.
5. Clock Generator Volume
Clock signals supplied to each digital IC of this device are all generated by IC402, except those
for the system microcomputer (40MHz, 33.8688MHz, 27MHz, 18.432MHz).
VDD of IC402 is synchronized with power-on/off by the system microcomputer.
Four types of frequency (oscillation) are generated by two reference oscillators
(X401 of 18.432MHz and IC407 of 27MHz).