Opel 1900 1973, Service Manual, Page: 618 / 625

S E R V I C E
c. Adjust screw for maximum volume,
d. If antenna does not have a definite peak,
check for ant&ma by substitution.
2. Check that the speaker connection is plugged in
securely.
3. If the radio is still weak, remove the receiver and
speaker assembly for repair.
Radio Is Noisy
1. Radio is noisy all the time:
a. Check for defective antenna by striking antenna
with hand. If static is heard while tapping, replace
antenna.
b. If antenna is not defective, remove receiver and
speaker for
2. Radio is noisy only when jarred:
a. Check antenna as in Step No. 1 above.
Check speaker connection. If speaker connection
is not at fault, remove receiver and speaker for re-
pair.
3. Radio is noisy when engine is running:
a. Check noise suppressor by substituting on genera-
tor with known good one.
b. Check to see that antenna is mounted securely,
grounding the antenna base to the fender. The an-
tenna lead-in wire is shielded and the shield should
have good ground
at the receiver and the
antenna base.
c. Check for other car wiring passing too close to
radio receiver case.
d. If engine noise is still present, remove receiver and
speaker for repair.
4. Radio is noisy when car equipment is operated,
such as directional lights or brake lights:
Check for defective antenna lead-in wire or loose
antenna mounting, as in Step No. 3b above.
5. Radio is noisy only on dry days when car is mov-
ing:
Wheel and tire static will occur only during dry
weather. To check to see if noise is wheel static or tire
static, drive car until noise is noticed. Touch the
brake. If noise disappears, it is wheel static. If noise
persists, it is tire static. Static may be eliminated
in
two ways:
a. Wheel static may be eliminated by installation of
static collectors in the front wheels. It is important
to make sure the button on the end of the spiral
collector rides evenly in the spindle. Grease and dirt
can cause poor contact between static collector and
the cap, which would result in wheel static, even with
the collectors installed.
b. Tire static is eliminated by injecting graphite tire
static powder in all (5) tires. Either a special gun
or a plastic squeeze bottle can be used to insert pow-
der.
MAINTENANCE AND ADJUSTMENTS
A N T E N N A T R I M M E R A D J U S T M E N T
An antenna trimmer adjustment screw is provided
for matching of the antenna coil in the receiver to the
car antenna. This adjustment must always be made
after installation of a receiver or an antenna, or after
repair to these units. This adjustment should also be
performed whenever radio reception is unsatisfac-
tory.
1. Position antenna to a height of 31 inches.
2. Tune receiver to a weak station at or near 1400
KHz that can barely be heard with volume turned
fully up.
3. Insert a small-bladed screwdriver in antenna trim-
mer screw and rotate screw until maximum volume
is achieved.
Figure Radio Control Knobs