Volvo Delco User manual

Service Bulletin
Volvo Trucks North America, Inc.
Greensboro, NC USA
Date Group No. Page
4.2004 392 08 1(47)
Trucks
This Service Bulletin replaces Service Manual 39, “Delco
Audio System Troubleshooting, VN” (12.1998), publication
number PV776–TSP109859. Audio System Design and Function
Delco/Delphi
VN, VHD
Audio System
Delco/Delphi
This service information covers the Delco/Delphi System Design and Function. For
further information refer to Group 3.
Contents:
•“VolvoVNSoundSystem”page2
•“RadioSignals”page3
•“Noise”page9
•“TroubleshootingConsideration”page10
•“StereoReceiver”page11
•“WeatherbandFamily”page11
•“HighPerformanceFamily”page14
•“CDChanger—HighPerformanceFamily”page27
•“CDChangerMagazine”page29
•“Amplifier”page38
•“Speakers”page39
•“Antenna”page41
•“Schematics”page45
Note: Information is subject to change without notice.
Illustrations are used for reference only and may differ slightly from the actual
vehicle being serviced. However, key components addressed in this information are
represented as accurately as possible.
PV776-20002689 USA14750

Volvo Trucks North America, Inc. Date Group No. Page
Service Bulletin 4.2004 392 08 2(47)
Volvo VN Sound System
The audio receiver systems in the Volvo VN series trucks
are selected and tuned for optimized performance. All
VN models are available with a variety of Delco/Delphi
Electronics components.
Three receiver families are available:
•The Weatherband family is available with or without
a cassette player or early production VNs through
approximately June 1999.
•The High Performance family is available with a
cassette or CD player on early production VNs through
approximately June 1999.
•The Extreme Audio family, known as XTA, is available
on later production VNs beginning approximately June
1999. It is standard on the VHD vehicles. The XTA
series is available in a “Basic” system with or without
a cassette player, and an “Uplevel” system with a
cassette or CD player.
All VN/VHD models are also available with either basic
or premium speaker packages. The VN 770 premium
speaker system includes an 8 channel amplifier and a
subwoofer. The VN 660 and VN 770 models are available
with remote CD changers.
Consult the “Owner’s Manual” that is supplied with the
vehicle for complete operation instructions.
Repair/Replacement
As an alternative to expensive replacement, Delco/Delphi
Electronics Devices may be repaired at approved service
centers. Call D&B Auto Radio at 1-800-323-4813 for
repair information.
Unauthorized Repair
The warranty may not apply if the product is worked on
by an unauthorized person.

Volvo Trucks North America, Inc. Date Group No. Page
Service Bulletin 4.2004 392 08 3(47)
Radio Signals
The radio signal is sent from a broadcast station and this
signal is then received by an antenna. The strength of the
signal depends on the following:
•The power output (wattage) of the broadcasting station.
•The location of the receiver relative to the broadcast
tower.
•Obstacles between the tower and the receiver.
•Atmospheric conditions.
•What band (AM or FM) the station is broadcasting.
•Type of antenna and the grounding bases.
In North America, commercial radio signals are legislated
into two bands:
•AM 530-1710 kHz (in 10 kHz steps)
•FM 87.9-107.9 MHz (in 200 kHz steps)
Each frequency range uses a different modulation
method. Since a radio wave is really just electromagnetic
energy, it must be controlled in a certain way to carry
information. The process of adding the information to the
radio signals is called modulation.
There are two modulation techniques used in radio
broadcasts:
•AM = Amplitude Modulation
•FM = Frequency Modulation
The characteristics of the signal depend on both
the frequency and the modulation. It is important to
understand these characteristics to properly verify a
complaint.

Volvo Trucks North America, Inc. Date Group No. Page
Service Bulletin 4.2004 392 08 4(47)
AM Band
W3003003
AM radio signals. (100 km = 62 miles)
Radio signals in the AM band have lower frequency
and longer wavelengths than the FM band. Some
characteristics of the AM band include:
•The frequency used is relatively low; therefore, these
waves can bend around obstacles and skip along the
ground.
•The waves are reflected by the ionosphere layer in the
atmosphere.
•Long range reception is sometimes available.
•AM is subject to electrical interferences.
•AM can be blocked by steel and/or concrete structures.
The AM frequencies have longer range due to the ground
wave. The ground wave follows the curvature of the
earth and is effected by its conductivity. The greater the
conductivity, the less the signal loss; so transmission
over water is better than over land. The ground wave in
this frequency band has a range of 80–320 kilometers
(50–200 miles).
The sky wave will pass through the atmosphere and
reflect off of the ionosphere to the vehicle’s antenna. At
night, the ionosphere is actually higher than during the
day, so it is possible for AM signals from great distances to
be received during nighttime hours. As a result, many AM
stations actually reduce transmitting power in the evening
hours to maintain the same coverage as during the day.

Volvo Trucks North America, Inc. Date Group No. Page
Service Bulletin 4.2004 392 08 5(47)
FM Band
W3003002
FM band signal. (100 km = 62 miles)
Radio signals in the FM band have higher frequency
and shorter wavelengths than the AM band. Some
characteristics of the FM band include:
•FM is able to eliminate atmospheric noise mainly due
to its method of propagation. Atmospheric noises are
generally amplitude related and have little effect on
FM signals.
•Reflect off of obstacles.
•Penetrate the ionosphere.
Radio frequencies over 30 MHz are effectively absorbed
by the earth, eliminating the ground wave. Even when out
of a direct line of sight, the signal may be reflected into
areas that would be in a “shadow” otherwise.
FM signals and light rays respond to atmosphere in a
similar manner. The atmosphere bends them both so they
will follow the curvature of the earth to a certain extent.
This is called refraction and it is similar to a lens which
can bend light waves. A good example of this is when
you see a sunset. The sunlight is visible with the sun well
below the horizon. FM signals characteristically have a
shorter range than AM signals.
Factors which affect the line of sight include:
•Height of the broadcast antenna.
•Height of the receiving antenna.
•Terrain and buildings in the broadcast path.