Pontiac FIREBIRD 1972 Service Manual page 1419

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15-4 1972 PONTIAC SERVICE MANUAL
RADIO (Fig.15-2)
Because radio problems are most often repaired at United
Delco authorized Warranty Repair Stations, the tendency
is to remove the set when a problem is reported, without
any preliminary diagnosis. This results in a large number
of radios showing up as "NO TROUBLE FOUND" units
when received by the Warranty Repair Stations. Many
times when this is the cause the trouble usually could have
been corrected without removal of the radio.
The inconvenience of driving without a radio while the set
is being serviced at a Warranty Station can frequently be
avoided if the following quick checks are used to eliminate
external radio system problems before removing the radio
for repair.
Always determine the exact nature of the radio problem
as an aid to diagnosis. Knowing whether the condition is
intermittent or constant, whether it occurs with engine off
or running, and whether it occurs with car stationary or
moving will help to pinpoint the problem.
The radio trouble diagnosis guide (Fig. 15-2) is intended
as an aid in locating minor faults which can be corrected
without a specialized knowledge of radio and without
special radio test equipment. If the suggestions given here
do not effect a correction, further testing should be done
only by a trained radio technician having proper test
equipment.
RADIO/TAPE (Fig. 15-3)
In diagnosing radiohape problems, the main point to
remember is that you now have both a radio and a tape
player to diagnose as part of the Stereo system. By insert-
ing test tape, 522683-01, you can quickly determine
whether the tape speed is proper. Since only the pre-amps
and audio are common to both radio and tape, by listening
for distortion with the tape playing and comparing it to
the radio signal you can further isolate the problem to
either radio or tape.
EIGHT TRACK STEREO TAPE PLAYER
(Fig. 15-3)
The tape player trouble diagnosis guide is intended as an
aid in locating minor faults which can be corrected with-
out a specialized knowledge of electronics and without
special test equipment. If the suggestions given here do not
effect a correction, further testing should be done only by
a trained radio technician having proper test equipment.
It should first be determined if the owner's tape and not the
player is at fault. Substituting a known good tape cartridge
for the owner's is a simple check.
CASSETTE STEREO TAPE PLAYER (Fig.
1 5-4)
Unlike the stereo eight track tape player, the Cassette
stereo player turns off automatically at the end of each
type. An inexperienced owner, or an owner accustomed to
the continuous-playing, eight track tape, may suggest that
a malfunction has occurred. By merely turning the tape
over, it will play through the program on the opposite
side. The diagnostic guide will assist in isolating the prob-
lem to a defective component in the system
--
radio-to-tape
harness, player, or speakers.
NOISE SUPPRESSION (Fig. 15-5)
If you are attempting to correct an interference or electri-
cal noise problem which is "abnormal", first check to see
that all of the proper suppression equipment is present and
that all of the suppression items are making good electrical
connections.
If all of the proper suppression equipment is present and
making good electrical connection, then the procedure in
Fig. 15-5 can be used to solve the more stubborn noise
problems. Also, review "IGNITION SUPPRESSION
EQUIPMENT" in General Description Section of this
section for description of normal noises.
WINDSHIELD ANTENNA (Fig. 15-6)
The following guide will aid in further diagnosing the
radio system, using the Windshield Antenna Tester J-
23520.
The spring shield must be on the Tester 5-23520 at all
times to direct the signal only to the area being tested.
Always check the tester on a known good car to make sure
it is operating properly and that the battery is not weak
or dead.