Cadillac 60 Series 1963 Shop Manual page 343

12-62 ELECTRICAL SYSTEM
The Cadillac AM/FM radio is equipped with
automatic frequency control, which causes the
tuner to tune directly to the station. An effort
should be made to tune the FM receiver directly
on station frequency; however, the automatic fre-
quency control will tune directly to and lock on
station frequency when s l i g h t mistuning is
encountered.
Another feature of FM tuning is signal sepa-
ration. When two FM stations are close in fre-
quency, the FM tuner selects the stronger signal,
completely rejecting the weaker one. This is in
contrast to AM performance, where it is not
always possible to separate two stations.
The Cadillac AM/FM Radio incorporates an
AM receiving circuit and an FM receiving cir-
cuit, both of which are of all-transistor con-
struction. The audio system is common to both
receiving circuits.
The signal seeking feature is not provided on
the AM/FM Radio. An AM/FM frequency band
switch is located above the frequency band on
the receiver dial, in place of the selector bar.
Located on either side of the AM frequency
band are tell-tale lights that indicate, when il-
luminated, which frequency band the receiver is
utilizing. The AM tell-tale light is located at
the left side of the band, and the FM tell-tale
light is found at the right side of the frequency
band.
Signal Seeking Tunner (Fig. 12-85)
The signal seeking tuner, provided on AM
Radios, is electronically controlled so that the
operator may change stations by depressing the
selector bar. The signal seeking operation con-
sists of a low to high frequency sweep (left to
right) of the broadcast band by the tuner.
pilot
Light
Sensitivity Control Switch
Signal Seeking
Selector Bar
Push Buttons
Fig. 12-85 AM Receiver Dial
When the selector bar is depressed, the tuner
moves to the station of next higher frequency
(to the right) and stops automatically at the
point where that station is best received. This
action takes place each time the selector bar
is depressed. When the tuner has reached the
point of highest frequency of the broadcast band,
it returns to the low frequency (left) side of the
broadcast band and begins a new sweep to the
right, stopping at the first receivable station.
The above procedure is then repeated.
A foot control switch, which performs the
same station selecting function as the station
selector bar, is available for dealer installation.
The stopping sensitivity of the signal seeking
tuner may be varied by changing the position of
the three-position sensitivity control switch lo-
cated just below the center of the selector bar.
When the selector bar is depressed, the signal
seeking tuner automatically selects the strongest
stations only, the strong and medium strong
stations, or all stations, depending upon the po-
sition of the sensitivity control switch.
SERVICE INFORMATION
81. Radio Controls Operation
a. Switch, Volume and Tone Control
(AM or AM-FM Radios)
The left know turns the radio ON and OFF,
and controls the volume. The ring on this knob
is the tone control. The ring is turned counter-
clockwise for bass tones and clockwise for treble
tones. When indexed at the detent, it provides a
balanced normal tone.
The radio will play immediately when turned
ON, due to the all-transistor construction of
the receiving and audio circuits.
b. Manual Station Selector and Speaker
Control (AM or AM-FM Radios )
The right knob is used to tune stations manu-
ally. The ring on the knob is the speaker control.
When the ring is turned all the way clockwise,
volume of the front speaker is predominant.
As the ring is turned clockwise, the front speaker
volume decreases while the rear speaker volume
increases. When the ring is turned all the way
counterclockwise, the rear speaker is predomi-
nant. Adjusting this ring will balance the volume
between the two speakers to please the driver
and passengers.