Pontiac Fiero 1988 Service Manual page 1246

RADIO SYSTEMS AND ANTENNAS 9A-3
electrical interferences. These include tall buildings,
metal structures, power lines, fluorescent lighting, and
power tools. Tune to high and low ends of the dial on
both AM and FM checking weak and strong station
reception. If reception is O K , problem exists with
antenna and/or its lead-in cable. If reception is still
poor, refer to Section 8A.
Checking lead-In Cables
Figure 2
Usually symptons of broken center conductor of
the lead-in cable will result in no AM and weak FM.
In case of continued reception or noise complaints,
always check the lead-in with an ohmmeter. The chart
and diagram shown in Figure 2 show readings which
should be obtained. When checking resistance,
cautiously wiggle the lead-in tip and cable. If the
readings shown in Figure 2 are not obtained, some
portion of the lead-in is intermittent and the lead-in
should be replaced.
CHECKING FIXED ANTENNAS
Unplug antenna lead-in at back of radio and plug
a test antenna into radio. Make sure test antenna base
is grounded to the car chassis and keep hands off of the
antenna (see "Testing for Good Grounds"). Check
radio reception in an area away from electrical
interferences. These include tall buildings, metal
structures, power lines, fluorescent lighting, and power
tools. Tune to high and low ends of the dial on both
AM and FM checking weak and strong station
reception. If reception is OK, problem exists with
antenna and/or its lead-in cable. If reception is still
poor, refer to Section 8A, page 150-0 or 151-0.
C - METAL D - METAL
Ohmmeter probes
Resistance measured
at points;
in ohms
A and
B
less than 0.5*
C and D
less than 0.5
A and
D
infinite
C
and
B
infinite
A and C
infinite
B
and D
infinite
*On some long lengths of lead-ins, such as power antennas,
capacitance is added in the tip. This results in a resistance
reading of approximately 100,000 ohms.
G 3 5 2 0 9 - 9 - E
Fig. 2 Lead-in Cable Diagnosis
SERVICE PROCEDURES
RADIO AND SPEAKERS
N O T I C E :
All radios are the bridge audio type,
using two wires to each speaker. It is very
important when changing speakers or performing
any radio work to avoid pinching the wires. A
short circuit to ground from either wire will cause
damage to the output circuit in the radio.
Also, all Delco sound systems have ungrounded
speakers. Installing add-on tape players, CB
radios or other units which use the car speakers
may damage your Delco sound system. Please
consult your dealer in advance if you are
considering additions.
See On-Car Service for radio or front speaker
replacement. See Body Service Manual at end of
this manual for door or rear speaker replacement.
RADIO NOISE SUPPRESSION EQUIPMENT
Figure 3
When installing a new radio, or when noise is a
problem, ensure that radio suppression equipment is
present and properly installed.
STEREO CASSETTE TAPE PLAYER
Figure 4
Tape and Tape Player Care
Optimum performance can be maintained by
cleaning the internal tape head, capstan, and pinch
roller periodically (approx. each 100 hours of
operation). This can be done by inserting a nonabrasive
cleaning cassette in place of the music tape.
DO NOT USE silicone spray lubricants for
switch, plunger or tape head lubrication.
NO LUBRICANTS should be used since they
cause the player to operate improperly, especially
at extreme temperatures.
Do not bring any magnetized tools near the tape
head. If the head becomes magnetized, every
cassette played will be degraded.
Store cassettes away from extreme heat or direct
sunlight. Protect the open ends from dirt or damage;
store them in their original cases or other protective
cases. For best results, 120 minute tapes are not
recommended.
When leaving the car, cassettes may be left in the
tape player (tapes are either automatically ejected or
internally protected).