1993 MITSUBISHI 3000GT CD player

Downloaded from www.Manualslib.com manuals search engine 54-158CHASSIS ELECTRICAL - Radio and Tape Player
TROUBLESHOOTING CHART
TSB Revision

Downloaded from www.Manualslib.com manuals search engine CHASSIS ELECTRICAL - Radio and Tape Player54-159
CHARTA. NOISE
A-l
Noise appears at certain places when traveling (AM).Is there a particular
stFind out the following information from the user:
1. Place
h YesDo the following measures eliminate the noise?
1. Change to a different station with a strong signalto boost resistance to interference.
2. Suppress high tones to reduce noise.
No
2. Locality conditions (valley, mountain, etc.)3. Name and frequency of stations affected by noise
tIf due to vehicle noise:
It may not be possible to prevent noise if the
signal is weak.
-I
t1 If due to external noise:
In almost all cases, prevention on the receiver
Weak signals especially are susceptible to inter-
i
tIf there is more noise than other radios, find out the noise conditions
and the name and frequency of the receiving stations from the user,and consult with the service center.
iTSB Revision

Downloaded from www.Manualslib.com manuals search engine 54-160CHASSIS ELECTRICAL - Radio and Tape Player
A-2Noise appears at certain places when traveling (FM).Do the following measures eliminate the noise?
YeslChange to a different station with a strong signal to boost resistance to interference.l Suppress high tones to reduce noise.+3cll Extend antenna completely. (Whip antenna)
No
tIf there is more noise than other radios, find out the noise conditions and the name and frequency
of the receiving stations from the user, and consult with the service center.
NOTE
About FM waves:
FM waves have the same properties as light, and
can be deflected and blocked. Wave reception isnot possible in the shadow of obstructions such
as buildings or mountains.
1.The signal becomes weak as the distance from
the station’s transmission antenna increases.
Although this may vary according to the signal
strength of the transmitting station and interven-ing geographical formations or buildings, the
area of good reception is approx.
20-25 km
(12-l 6 miles) for stereo reception, and 30-40km (19-25 miles) for monaural reception.
2. The signal becomes weak. when an area of
shadow from the transmitting antenna (places
where there are obstructions such as mountains
3.
4.
or buildings between the antenna and.the car),
and noise will appear. and gives a steady buzzing noise.>
If a direct signal hits the antenna at the same
time as a signal reflected by obstructions such
as mountains or buildings, interference of the
two signals will generate noise. During traveling,
noise will appear each time the vehicle’s anten-
na passes through this kind of obstructed area.The strength and interval of the noise varies
according to the signal strength and the condi-tions of deflection.
noise, and is a repetitious buzzing.>Since FM stereo transmission and reception
has a weaker field than monaural, it is often
accompanied by a hissing noise.FM Broadcast Good Reception Areas
FM Signal Characteristics and Signal Interference
For home stereos:80-90 km (SO-56 miles):.:,.::..:,.::.‘; .: ‘, “.‘l’.. ”216AO664Z16A066300002401
Iji
I
TSB Revision

Downloaded from www.Manualslib.com manuals search engine CHASSIS ELECTRICAL - Radio and Tape Player54-161
iA-3Mixed with noise, only at night (AM).
L
ii
i
The following factors can be considered as possible
causes of noise appearing at night.1. Factors due to signal conditions: Due to the
fact that long-distance signals are more easily
received at night, even stations that are received
without problem during the day may experience
interference in a general worsening of reception
conditions. The weaker a station is the more
susceptible it is to interference, and a changeto a different station or the appearance of a
beating sound* may occur.
Beat sound*: Two signals close in frequency
interfere with each other, creating a repetitious
high-pitched sound. This sound is generated
not only by sound signals but by electrical waves
as well.
2.Factors due to vehicle noise: Generator noisemay be a cause.
the
lamps OFF?
Yes
t1 Do the following measures eliminate the noise? 1 yes cl/l Tune to a station with a strong signal.
l
Tune to a station with a strong signal without com-cletelv extending the antenna.
No
IDoes the noise fade away when the vehicle har-ness is moved away from the radio chassis?
(if the harness is not in the proper position).
NoIf there is more noise than other radios, consult a service
center.
TSB Revision

Downloaded from www.Manualslib.com manuals search engine 54-I 62CHASSIS ELECTRICAL - Radio and Tape Player
A-4
Broadcasts can be heard but both AM and FM have a lot of noise.
(1)Noise occurs when the engine is stopped.
YesJ
(2)Noise occurs when the engine in running.
Do the following measures eliminate the noise?
@ Tune to a station with a strong signal.
l Extend the antenna completely. (Whip antenna)
l Adjust the sound quality to suppress high tones.
NoIs the radio body ground mounted securely?
Yes
Securely tighten the nuts for the bodyground.
Yes
YesClean the antenna plug and ground
wire mounting area. Mount the anten-
na securely. On a vehicle with a motor
antenna, check the antenna itself. (Re-fer to E-1, 2.)
If there is more noise than other radios, consult a servicecenter
NOTE
About noise encountered during FM reception only.
Due to differences in FM and AM systems, FM is
noise interference (first fading and multipath). (Refer
to A-2.)
not as susceptible as AM to interference from en-
gines, power lines, lightning, etc. On the other hand,
problem with the radio.>waves of noise or distortion generated by typical
TSB Revision

Downloaded from www.Manualslib.com manuals search engine 54-164CHASSIS ELECTRICAL - Radio and Tape Player
A-6There is noise when starting the engine.
Noise type
Sounds are in pa-
rentheses ( ).
AM, FM:
Ignition noise
(Popping, Snap-
ping,Cracking,
Buzzing)
Otherelectrical
components
Static electricity
(Cracking, Crin-
kling)
Conditions
0Increasing the engine speedcausing the popping sound tospeed up, and volume de-creases.0Disappears when the ignitionswitch is turned to ACC.
-
lDisappears when the vehicle is
completely stopped.Occurs when parts or wir-
Severe when the clutch is en-ing move for some reasonlgaged.and contact metal parts of
the body.
lVarious noises are produced de-pending on the body part of thevehicle.
Due to detachment from
the body of the front hood,
bumpers, exhaust pipe
and muffler, suspension,
etc.
Causel
Mainly due to the
spark plugs.l Due to the enginenoise.
Noise may appear as
electrical components be-
come older.
Parts to be Location of
inspectedparts
or remedy(next page)
Noise con- 1
denser
Ground
cable2, 3
Repair or replace electricalcomponents.
Return parts or wiring to
their proper position.
Caution
1.Connecting a high tension cable to the noise
filter may destroy the noise filter and shouldnever be done.
2.Check that there is no external noise. Since
failure to do this may result in misdiagnosis
due to inability to identify the noise source,
this operation must be performed.3. Noise prevention should be performed by
suppressing strong sources of noise step
by step.
NOTE
1. Condenser
The condenser does not pass D.C. current, butas the number of waves increases when it
passes A.C. current, impedance (resistanceagainst A.C.) decreases, and current flow is
facilitated. A noise suppressing condenser
which takes advantage of this property is in-
serted between the power line for the noise
source and the ground. This suppresses noiseby grounding the noise component (A.C. or
pulse signal) to the body of the vehicle.
2. Coil
The coil passes D.C. current, but impedance
rises as the number of waves increases relativeto the A.C. current. A noise suppressing coil
which takes advantage of this property is in-
serted into the power line for the noise source,
and works by preventing the noise componentfrom flowing or radiating out of the line.
1 TSB Revision
Ground parts by bonding.
Cases where the problem
is not eliminated by a single
response to one area are
common, due to several
bodypartsbeing
imperfectly grounded.

Downloaded from www.Manualslib.com manuals search engine CHASSIS ELECTRICAL - Radio and Tape Player54-165
NOISE SUPPRESSION PARTS MOUNTING POSITIONS
1/ Noise con::;;, 1
TSB Revision

Downloaded from www.Manualslib.com manuals search engine 54-166CHASSlS ELECTRICAL - Radio and Tape Player
IA-7Some noise appears when there is vibration or shocks during traveling.
‘d ~
Are connectors properly connected?
YesNo
---+ Ensure proper connection
t
Does noise appear when the radio switch is turned on while theNovehicle is stopped and the radio is struck while tuned away fromLa station?
YesStatic electricity noise:
Body static electric from the shock absorber rubber bushings used
to prevent vibration, tires, etc. occurs because of separation fromthe ground, causing a buzzing noise.
Since no measures can be taken on the radio side, steps shouldbe taken to discharge the static electricitv of the vehicle bodv.
tIs the radio correctly grounded?
(Is the mounting screw tightened securely?)
1 Yes
tIs the antenna correctly grounded? (If noise appears when the Nocantenna is moved, this means the ground is not securely con-
nected.)
If rust is present on the antenna ground screw, clean and tightenthe ground securely.
Yes
1 Reoair or reolace radio.1
TSB Revision