505 V6-2849cc 2.8L ZN3J (1987)
Antenna: All Technical Service Bulletins
Radio - Excessive Noise (Static) On AM Band
BULLETIN NO. 211 (
15)
DATE:
January, 1987 (43)
SUBJECT:
EXCESSIVE IGNITION NOISE (STATIC) ON AM BAND
COMPLAINT AND REASON FOR COMPLAINT
The tuner on the new 1987 Alpine Anti-Theft Radio is vastly improved on both AM and FM bands, Radio stations may now be listened to even further
from the transmitter with improved clarity.
As the AN automatic gain control circuit "reaches for" the very weak stations, it may also pull in more static from:
a.
stoplight switch being activated on & off
b.
directionals being activated on & off
c.
cruise control mode switch turned off
d.
ignition
Ignition noise may be easily recognized as a "cracking noise" that:
a.
increases in frequency as engine RPM's increase
b.
increases in loudness during acceleration (due to higher spark plug firing voltage requirements)
In city areas, excessive ignition noise may occur momentarily when traveling under over-passes, making diagnosis easy.
FM is not affected by static due to its "noise blanker circuit."
REPAIR
1.
Grounding of chassis components is critical. Insure that all ground straps are installed and making good contact.
