Sony EA-80 Service Manual page 16

1. Communication
In case LLC-8000 sends data "0"
The LLC-8000 turns the voltage at the D.SIG terminal(pin 4 of CN1) on the AU-254 board to 0 V.
It then turns the voltage at the pin 1 of the CPU(IC1) on the SW-952 board to 0.5 V, and the CPU recognizes data as "0".
In case EA-80 sends data "0"
The EA-80 turns the voltage at the pin 3 of the CPU(IC1) on the SW-952 board to 0 V.
When the voltage at the pin 3 of the CPU is 0 V, the parts, R13, 17 and 18 on the SW-952 board, and also Ra and Rb on the
LLC-8000, turn the voltage at the D.SIG terminal(pin 4 of CN1) on the AU-254 board to 0.5 V. The RxD terminal on the
LLC-8000 recognizes data as "0" because the D.SIG terminal becomes 0.5 V.
2. Audio
The audio input and output levels are shown below. The VOLUME, control knob (RV1) on the SW-952 board adjusts
a sound level from -8 dB to +8 dB. (The RV1 cannot control AUX L IN and AUX R IN signals.)
OUTPUT
INPUT (LEVEL)
PGM -10 dB
INCOM -10 dB
HS-MIC -54 dB
AUX L -10 dB
AUX R -10 dB
LLC-8000
MONI
CN1-5
{-10.5dB}
[-17dB]
PGM CN1-3
(-10dB)
INCOM CN1-8
<-10dB>
+15V CN1-7
5V
TXD
R
a
CN1-4
5V
R CN1-1
b
RXD
CN1-6
CN1-2
EA-80
SECTION 5
BLOCK DIAGRAM
HS-PHONE(L) HS-PHONE(R)
-19 dB
Turning Q1 on makes sound mute.
-19 dB
-19 dB
Turning Q2 on makes sound mute.
-19 dB
X
EA-80
1
MONI
2
Q2
S-MIC SW
2
PGM
Q1
PGM-MONI SW
INCOM
VOLUME
RV1
+15V
5V
R18
D.SIG
R13
P.GND
COLD
A.GND
0dB=0.775Vrms SIGNAL:1KHz VOLUME:CENTER
MONI
-19 dB
X
-19 dB X
-19 dB
-10 dB
X -16 dB
-19 dB -16 dB
[-10dB]
AUX L IN CN3-1
[-10dB]
AUX R IN CN3-2
(-10dB)
PGM OUT CN3-4
{-11dB}
MIC OUT CN3-5
1
(-11dB)
<-10dB>
{-11.5dB}
{-54dB}
HS-MIC J1-1
3
J2-1
HS-PHONE(L)
3
HS-PHONE(R) J2-2
(-36.5dB)
{-20dB} (-19.5dB)
<-35.5dB>
[-20dB] <-18.5dB>
{-37dB}
IC1
D1~6 SW1~6
R17
3
TXD
1
RXD
SW-952 BOARD
PGM
-10 dB
X
X
X
X
Level allowance: ±3 dB
X: No output
Frequency response: 50 through 10 kHz; +3/-10 dB
MIC
X
X
-10 dB
X
X
5-1