Hitachi DV-P505E, Service Manual

Page: 15 / 58

Chapter 1 9
Video Output Circuit (VDO substrate)
Analog composite video signals (CVBS), analog luminace signals (Y), analog chroma signals (C) and analog
component signals (YP
B
P
R/RGB)
are sent from DEC substrate to VDO substrate by passing through 17P
connector (PG2201~PG1302). From VDO substrate, CVBS signals are output from output terminal J1307 and
Y/C signals are output from output terminal J1302. Component signals are output from output terminal J1306
(YP
B
P
R
) or J1361 (RGB).
Audio Circuit
Audio circuit is shown in page 11.
Audio circuit is composed of D/A converter sector (DEC substrate) that transforms digital audio signals output from
A/V processor (IC1201), analog processing sector (RJK substrate) that consists of an operational amplifier, and
mute circuit (DEC substrate, RJK substrate) for stopping audio output when required.
1. D/A CONVERTER SECTOR (DEC substrate)
D/A converter sector is composed of IC1503 that receives and transforms digital audio signals from A/V
processor in analog signals.
IC1503 is a converter corresponding to FL and FR signals of sampling frequencies 44.1/48/96KHz and
data lengths16/20/24bit, and digital audio signals from A/V processor is input at pin 2.
To these digital audio signals are inserted FL and FR signals in time sharing mode. When they are input in
pin 1, they are separated in FL and FR signals by R clock and after transformation analog FL signals are
output at pin 16 and FR signals at pin 13. Moreover, when there are no input signals at pin 2, a signal
called ZERO MUTE is output to pin 21 to mute useless noises (See paragraph on MUTE CIRCUIT.)
Every functions of IC1503 is preset by IC 1201and controlling signals from IC1201 are input at pins 26,
27,and 28. As for presetting items, there are data length, sampling frequency, signal polarity, and de-
emphasis.
2. ANALOG PROCESSING SECTOR (RJK substrate)
Analog processing sector is composed of operational amplifier IC1508 that is a filter and operational
amplifier IC1510 that amplifies audio signals.
Filter portion is composed of RC low pass filter and IC1508 formed active low pass filter and there are 3
sections. The diagram below shows its filter portion circuit (for FL signals only).
VIDEO
S
COMPONENT
PG2201 PG1302
J1307
J1302
J1361
J1306
DEC Substrate VDO Substrate
SCART
SQUEEZE