Circuit Description; Description Of Components - Kenwood DPC-77 Service Manual

CIRCUIT DESCRIPTION
DESCRIPTION OF COMPONENTS
Component Use/Function
Operation/Condition/Compatibility
ul Switching regulator DC/DC converter switch.
U101 RF amplifier See the IC description. (p.13)
-U301
Servo amplifier See the IC description. (p.19}
| U302 Operation amplifier Amplifies the feed motor drive signal.
U351 Actuator control See the IC description. (p.24)
U352 Motor control See the IC description. (p.24)
U401 Digital signal processor
See the IC description. (p.25)
402 Static RAM See the IC description. {(p.51)
U403 MMigtoptneasenr See the IC description. (p.48)
U404
Digital filter See the IC description. (p.47)
U501
D/A converter
See the IC description. (p.52)
U502
Audio amplifier Buffer amplifier for DAC output.
LPF
Lew: pass filter.
6-INVERT Digital out signal buffer
Oberational Amnniier: 1/2 Vcc generator for the audio Circuit.
Switching regulator
Controls the charging circuit.
DC/DC converter output Switch Turns the DC converter Sitar ON/OFF.
DCIDC converter output switch control
Turns Q1 ON/OFF.
Reset swine Turns the reset circuit ON/OFF.
Lo swiiteh
Low battery indicator switch
'Goes ON wel the battery voltage is 5. 5 v or less.
i ; Focusing signal switch
Switches the pickup's laser diode ON/OFF.
Holds the focusing offset Position during playback of a scratched disc (DEFECT- a
Tracking
[i
Turns the ATSC ci circuit ON during KEY LOCK.
Focusing gain switch Increases the focusing gain during KEY LOCK.
Power awiek
Switches the power to the whole system, except for the CPU.
Actuator/motor driver power switch -
Emphasis
Supplies power to the actuator and motor drive IC.
Applies emphasis when an emphasis signal is detected by the CPU.
High filter
When the key is pressed, the CPU outputs an ON/OFF signal to switch the filter
circuit ON/OFF.
"Muting Mutes the audio signal.
Q505
Muting driver Controls Q506. When the microprocessor outputs the muting signal, Q505 receives
it and turns the signal level ON/OFF.
Q506 Muting driver
Turns the muting driver ON/OFF. if the supply voltage drops (to 3.5 V), Q507 goes
OFF to turn the muting drivers ON.
Q805, 806,
808
Ripple filter
Ripple filter for the audio circu power supply.
Q807 Ripple filter switch
Switches the audio circuit power . ON/OFF according to an n ONIOFF signal from the CPU.
Q901
Charger circuit switch Turns the charger circuit ON/OFF.
Q903 :
Power switch Turns the charging output voltage ON/OFF.