Opel 1900 1973 Service Manual page 614

1973 OPEL SERVICE MANUAL
c. Adjust trimmer screw for maximum volume.
d. If antenna trimmer does not have a definite peak,
check for defective antenna by substitution.
2. Check that the speaker connection is plugged in
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 repair.
2. Radio is noisy only when jarred:
a. Check antenna as in Step No. 1 above.
b. 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 connection 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.
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 adjusment 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 re-
pair 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 tb 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-
Figure 9C-1 Location of Access Trim Plug
Figure 9C-2 Removing Hex Head Screw