Kenwood KAC-929 Service manual
POWER AMPLIFIER
KAC-929
SERVICE MANUAL
© 2001-3 PRINTED IN KOREA
B51-7768-00 (K) 3380
POWER AMPLIFIER
LEFT
BRIDGED
SPEAKER
OUTPUT
RIGHT
POWER IN
P.CONBATT.
GND
30
30
FUSE(30Ax2)
KAC-929
STEREO/BRIDGEABLE
AMPLIFIER
MAXIMUM POWER
SCREW SET
(N99-1587-05)
ACCESSORY
(W01-1516-05)
CONNECTING CORD ASSY
(E30-4950-05)
ISOLATION
AMPLIFIER
L
ISOLATION
AMPLIFIER
R
B.BOOST EXPANDER INVERTER
SW3 SW4
SW1
(L)
INPUT SENS.
MIXER
LOW
PASS
SW2
IC1
IC2
IC3 IC3
IC4
BUFFER
IC3
MUTE
Q3
STAGE
DIFFERENTIAL
107,109,111
Q101,103,105,
B-CLASS
121,123,125,127
Q113,115,117,119,
STAGE
OFF/+6/+12
BASS BOOST
OPERATION
ST/MONO
LPF
ON/OFF
EXP.
ON/OFF
INPUT SENS.
(R)
B.BOOST
IC2
SW3
EXPANDER INVERTER
SW4
BUFFER
IC3
MUTE
Q4
Q114,116,118,120,
STAGE
Q102,104,106,
108,110,112
DIFFERENTIAL
STAGE
122,124,126,128
B-CLASS
OUTPUT
SPK.
SPK.
OUTPUT
V
SPK
L
SPK
R
DC DETECTOR
OVER LOAD DETECTOR
DC/DC
CONVERTER
CIRCUIT
OVER VOLTAGE
PROTECTION
THERMAL
AVR
Q1,2 Q11-22
IC5
Q5-8,29-33
Q24
P.CON
CIRCUIT
Q23,25-28
P.C.
BATTERY
V
IC1
2
KAC-929
BLOCK DIAGRAM
-20
-20 -10 0 +10
-10
0
+10
(dB)
(dB)
OUTPUT LEVEL
INPUT LEVEL
Fig.1
(A)
(B)
(C)
-20
-20
1.1dB
2.1dB
3.2dB
5.3dB
6.5dB
0.7dB
0.15W
-30
-30
-10 -5-7-15-25 0
0
150W
15W
1.5W
-10
(dB)
(dB)
OUTPUT LEVEL
INPUT LEVEL
Fig.2
200mV
63mV20mV6.3mV
(4Ω)
0dB=24.5V (4Ω 150W)
R2 20K
GAIN
VARIABLE
R1 10K
RECTIFIER
R3 20KR4 30K
THD TRIM R3 INVERTER IN
RECT CAP
VREF
OUTPUT
1.8V
RECT IN
G IN
Fig.3
[Expander Circuit]
KAC-929
CIRCUIT DESCRIPTION
The expander circuit has been designed to expand
the range of audio.
Specifically, it inputs a signal with variation over 10
dB and outputs a signal with variation over 20 dB.
In other words, the expander circuit can make loud
sound louder and small sound smaller.
Its characteristic is as shown in Figure 1, which
shows its characteristic (B) in comparison with the
characteristic of an ordinary amp (A).
Figure 2 shows the characteristics of the expander
amp used in this set.
It shows that the effect described above is applied in
the same way all over the bandwidth
(A) Characteristic of ordinary amp
(B) Characteristic of expander
(C) Characteristic of expander amp used in the set
The point in incorporating an expander circuit in this
set is to make the audio more powerful, with punch in
it.
The expander amp used in the set outputs similar
audio to ordinary amp when the input level is low,
while it can provide powerful audio with punch when
the input level is above a certain level.
Appendix
IC4 block diagram is as shown in Figure 3.
3
KAC-929
No. ITEM
INPUT
SETTINGS
OUTPUT
SETTINGS
RECEIVER
SETTINGS
ALIGNMENT
POINTS
ALIGN
FOR
FIG.
Connect a cassette receiver or CD receiver.
1 IDEL CURRENT -
Connect a DC
voltmeter
between CN2
(L/R) and J2
(SP.OUT, L+/R-)
VOLUME : 0
VR3 (L ch)
VR4 (R ch)
(X09-)
2.5mV (a)
DC Voltmeter
(a)2.5mV
DC Voltmeter
(a)2.5mV
VR4(Rch)
VR3(Lch)
CN2
Lch
Rch
SP. OUT
L
R
ADJUSTMENT
4
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