Kenwood Car Stereo System KAC 749S User Manual

Troubleshooting Guide  
What might appear to be a malfunction in your unit may just be the result of slight misoperation or  
miswiring. Before calling service, first check the following table for possible problems.  
PROBLEM  
POSSIBLE CAUSE  
SOLUTION  
No sound.  
(No sound from one side.)  
• Input (or output) cables are  
disconnected.  
• Connect the input (or output)  
cables.  
• Protection circuit may be  
activated.  
• Check connections by referring  
to "Power indicator".  
• Replace the fuse and use lower  
volume.  
• After check the speaker cord and  
fixing the cause of the short,  
replace the fuse.  
KAC-849  
(Blown fuse.)  
• Volume is too high.  
• The speaker cord is shorted.  
KAC-749S  
The output level is too  
small (or too large).  
The input sensitivity adjusting  
control is not set to the correct  
position.  
Adjust the control correctly  
referring to "Controls".  
4-CHANNEL POWER AMPLIFIER  
INSTRUCTION MANUAL  
The sound quality is bad.  
(The sound is distorted.)  
• The speakers wire are  
connected with wrong + / -  
polarity.  
• Connect them properly checking  
the + / - of the terminals and  
wires well.  
• A speaker wire is pinched by a  
screw in the car body.  
• Connect the speaker wire again  
so that it is not pinched by  
anything.  
• The switches may be set  
improperly.  
• Set switches properly by  
referring to "System examples".  
Specifications  
Specifications subject to change without notice.  
Audio Section .....................................................................KAC-849 KAC-749S  
Max Power Output (4 )  
4 Channel Mode ...................................................................100 W × 4 80 W × 4  
3 Channel Mode...............................................100 W × 2 + 300 W × 1 80 W × 2 + 250 W × 1  
2 Channel Mode ...................................................................300 W × 2 250 W × 2  
Rated Power Output (4 )  
4 Channel Mode (20 Hz ~ 20 kHz, less than 0.08 % THD).....50 W × 4 40 W × 4  
4 Channel Mode (DIN45324, +B=14.4V)................................50 W × 4 40 W × 4  
3 Channel Mode (20 Hz ~ 20 kHz, 0.08 % THD) + (1 kHz, 0.8 % THD)  
...........................................................................50 W × 2 + 150 W × 1 40 W × 2 + 120 W × 1  
2 Channel Mode (1 kHz, 0.8 % THD)....................................150 W × 2 120 W × 2  
Rated Power Output (2 )  
4 Channel Mode (1 kHz, 0.8 % THD)......................................75 W × 4 60 W × 4  
Frequency Response (+0, –3 dB)......................................5 Hz ~ 50 kHz 5 Hz ~ 50 kHz  
Signal to Noise Ratio ....................................................................100 dB 100 dB  
Sensitivity (MAX) (rated output).......................................................0.2 V 0.2 V  
Sensitivity (MIN) (rated output)........................................................5.0 V 5.0 V  
Input Impedance ............................................................................10 k10 kΩ  
Low Pass Filter Frequency (12 dB/oct.) (Variable)................50 ~ 200 Hz 50 ~ 200 Hz  
High Pass Filter Frequency (12 dB/oct.) (Variable)................50 ~ 200 Hz 50 ~ 200 Hz  
Bass Boost Circuit (90 Hz)................................................................6 dB 6 dB  
Take the time to read through this instruction manual.  
Familiarity with installation and operation procedures will help  
you obtain the best performance from your new power amplifier.  
For your records  
Record the serial number, found on the back of the unit, in the spaces  
designated on the warranty card, and in the space provided below.  
Refer to the model and serial numbers whenever you call upon your  
KENWOOD dealer for information or service on the product.  
Model KAC-849/749S Serial number  
General..................................................................................KAC-849 KAC-749S  
Operating Voltage (11 ~ 16 V allowable) .......................................14.4 V 14.4 V  
Current Consumption (1 kHz, 10 % THD) ........................................31 A 26 A  
Dimensions (W × H × D)...........................................261 × 57 × 256 mm 261 × 57 × 256 mm  
......................................................................(10-1/4×2-1/4×10-1/16 in.) (10-1/4×2-1/4×10-1/16 in.)  
Weight................................................................................3.5 kg (7.7 lb) 3.5 kg (7.7 lb)  
© PRINTED IN USA B64-1969-00 (KM/EM)  
Wiring  
Safety precautions  
Accessories  
Installation procedure  
1.Remove the ignition key and disconnect the  
negative - terminal of the battery to prevent  
short circuits.  
• If a buzzing noise is heard from the speakers  
External  
View  
Number of  
Items  
when the engine is running, connect a line noise  
Part name  
2WARNING  
filter (optional) to each of the battery wire.  
To prevent injury or fire, take the following  
precautions:  
• When extending the ignition, battery, or ground  
wires, make sure to use automotive-grade wires or  
other wires with a 5mm (AWG10) or more to  
prevent wire deterioration and damage to the wire  
coating.  
• To prevent a short circuit, never put or leave any  
metallic objects (such as coins or metal tools) inside  
the unit.  
• If the unit starts to emit smoke or strange smells,  
turn off the power immediately and consult your  
Kenwood dealer.  
• Do not touch the unit during use because the surface  
of the unit becomes hot and may cause burns if  
touched.  
• Do not allow the wire to directly contact the edge  
of the iron plate by using Grommets.  
Terminal cover  
(Power terminal)  
1
4
1
2.Set the unit according to the intended usage.  
3.Connect the input and output cables of the  
units.  
• Connect the ground wire to a metal part of the  
car chassis that acts as an electrical ground  
passing electricity to the battery‘s negative -  
terminal. Do not turn the power on if the ground  
wire is not connected.  
• Be sure to attach a protective fuse into the  
battery wire close to the battery. Use a  
protective fuse having a capacity that is about 10  
A higher than the maximum current drawn by the  
amplifier.  
• Use vehicle-type (fire-resistant) power supply  
wiring wire for the battery wire and the ground  
wire. The current capacity of the power supply  
wiring wire should be about 10 A higher than that  
of the protective fuse capacity (which means  
about 20 A higher than the maximum current  
drawn by the amplifier).  
• When more than one power amplifier are going  
to be used, use a power supply wiring wire and  
protective fuse of greater current-handling  
capacity than the total maximum current drawn  
by each amplifier.  
Self-tapping screws  
2
(ø4 × 16 mm)  
4.Connect the speaker wires.  
Speaker level input  
cable  
5.Connect the power wire, power control wire  
and grounding wire following this order.  
6.Install the unit in the car.  
7.Connect the negative - terminal of the battery.  
Installation  
2WARNING  
Since the power amplifier has no parts which require  
operation, it can be installed at a position away from  
the driver’s seat without any hindrances.  
As generally accepted positions for its installation,  
places such as inside the trunk, etc. can be  
considered.  
To prevent fire caused by a short in the wiring,  
connect a fusible link or breaker nearby the  
battery’s positive terminal.  
2CAUTION  
• Be sure to turn the power off before changing the  
setting of any switch.  
2CAUTION  
2CAUTION  
To prevent damage to the machine, take the  
following precautions:  
• If the fuse blows, check wires for shorts, then  
replace the fuse with one of the same rating.  
• Check that no unconnected cables or connectors  
are touching the car body. Do not remove caps from  
unconnected cables or connectors to prevent short  
circuits.  
• Connect the speaker wires to appropriate speaker  
connectors separately. Sharing the negative wire of  
the speaker or grounding speaker wires to the metal  
body of the car can cause this unit to fail.  
• After installation, check that the brake lamps,  
winkers, and wipers work properly.  
• Do not install the unit under the carpet. Otherwise  
heat build-up occurs and the unit may be damaged.  
• Install this unit in a location which allows heat to  
easily dissipate. Once installed, do not place any  
object on top of the unit.  
• The surface temperature of the amplifier will  
become hot during use. Install the amplifier in a  
place where people, resins, and other substances  
that are sensitive to heat will not come into contact  
with it.  
• When making a hole under a seat, inside the trunk,  
or somewhere else in the vehicle, check that there  
is nothing hazardous on the opposite side such as a  
gasoline tank, brake pipe, or wiring harness, and be  
careful not to cause scratches or other damage.  
• Do not install near the dashboard, rear tray, or air  
bag safety parts.  
• The installation to the vehicle should securely fasten  
the unit to a place in which it will not obstruct  
driving. If the unit comes off due to a shock and hits  
a person or safety part, it may cause injury or an  
accident.  
• Be sure the unit is connected to a 12V DC power  
supply with a negative ground connection.  
• Do not open the top or bottom covers of the unit.  
• Do not install the unit in a spot exposed to direct  
sunlight or excessive heat or humidity. Also avoid  
places with too much dust or the possibility of water  
splashing.  
• When replacing a fuse, only use a new one with the  
prescribed rating. Using a fuse with the wrong rating  
may cause your unit to malfunction.  
Example: One Power Amplifier Is Used  
Maximum Current Drawn  
Protective Fuse  
Cross-sectional Area of  
Wiring Wire (AWG)  
31 A / 26 A  
50 A × 1 [25 A × 2]  
2
5 mm (AWG 10) or  
greater × 1  
• To prevent a short circuit when replacing a fuse, first  
disconnect the wiring harness.  
25 A  
25 A  
Speaker level input terminals (!)  
• The genuine-accessory car stereo shall have a  
maximum power output of no more than 40 W.  
• Do not connect the speaker output leads from  
a power amplifier (Optional) to the speaker  
level input terminals of this unit, for this may  
cause malfunction or damage.  
• Do not connect cables and leads to both RCA  
cable input jacks and the speaker level input  
terminals simultaneously, for this may cause  
malfunction or damage.  
• Connect the power control lead to a power  
supply which can be turned ON/OFF by the  
ignition key switch (ACC line). With this  
connection, shock noise may be generated  
when the power of the genuine-accessory car  
stereo is switched ON/OFF.  
25 A  
25 A  
NOTE  
• If you experience problems during installation,  
consult your Kenwood dealer.  
• If the unit does not seem to be working right, consult  
your Kenwood dealer.  
Speaker Selection  
• The rated input power of the speakers that are  
going to be connected should be greater than  
the maximum output power (in Watts) of the  
amplifier. Use of speakers having input power  
ratings that are less than the output power of  
the amplifier will cause smoke to be emitted as  
well as damage.  
FCC WARNING  
This equipment may generate or use radio frequency  
energy. Changes or modifications to this equipment  
may cause harmful interference unless the  
modifications are expressly approved in the instruction  
manual. The user could lose the authority to operate  
this equipment if an unauthorized change or  
modification is made.  
• After installing the unit, check to make sure that  
electrical equipment such as the brake lamps, turn  
signal lamps and windshield wipers operate  
normally.  
• The impedance of the speakers that are going to  
be connected should be 2or greater (for  
stereo connections), or 4or greater (for  
bridged connections). When more than one set  
of speakers are going to be used, calculate the  
combined impedance of the speakers and then  
connect suitable speakers to the amplifier.  
Self-tapping screw  
(ø4 × 16 mm)  
Cleaning the unit  
If the front panel gets dirty, turn off the power and  
wipe the panel with a dry silicon cloth or soft cloth.  
Power terminal (234)  
Connect to their respective terminals the power  
supply wire, and ground wire, all of which pass  
through the associated terminal cover. Once the  
connections are complete, place the cover on  
the terminal section.  
4Ω  
2CAUTION  
4Ω  
4Ω  
Do not wipe the panel with a hard cloth or a cloth  
dampened by volatile solvents such as paint thinner  
and alcohol. They can scratch the surface of the panel  
and/or cause the indicator letters to peel off.  
4Ω  
8  
2 Ω  
Installation board, etc.  
(thickness : 15 mm or more)  
 

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