Circuit Description - Kenwood KAC-PS621 Service Manual

Current detection circuit
Amplify and rectify potential differences at
two points in the primary-side current circuit
and send it to the AD-port of the MPU and
obtain data for displaying current value.
Constant current output circuit
Remove troubles caused by the potential
differences between the constant current
output and the GND, so that the GND po-
tential differences between the H/U and the
AMP is not overlapped in the AMP to H/U
communication.
I2C buffer
Using an IC for I2C communication, be-
tween-AMP communication is conducted so
that there will be no trouble from GND po-
tential differences.
No. Item Alignment Point
1 IDEL CURRENT

CIRCUIT DESCRIPTION

MPU AD-PORT
OUTPUT
J3
to OTHER AMP
TRANSMISSON
RECEIVE
J4
5
10
11
ADJUSTMENT
Method
VR1 (Lch) Connect a DC voltmeter between
VR2 (Rch) check land A, B.
KAC-PS621/X621
0.01 0.01
10K
4 6
7
1K
5
10K
IC9
D309 (2/2)
AMP RECT
4 3 2 1
8 7 6 5
to H/U
12 11 10 9
REQC
13
H/U-GND
H/U GND
270
2 4
CLK
3
1
7 9
270
8
6
DATA
D301
10u25
10K
Align For
2.5mV
VOLTAGE
LEVEL
DETECTION
13K
L5
470
2
1
3
8
IC9
(1/2)
Q301
Q305
47 47
Q307
10K
Q303
10K
CONSTANT
CURRENT
D302
IC3
to MPU
TRANSMISSON
RECEIVE
BOTH DIRECTION
BUFFER
Note Fig.
After Power on PC board
2 minutes (X09-577)
from
MPU
AMP
GND
7