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RADIO AND OTHER ACCESSORIES
RADIO
11-3
between antenna sections. Screws holding
windshield division (inner) molding should be
checked to see that they have not pierced insula-
tion of lead-in wire, shorting it to the car body.
°
b . Trouble Caused by Tubes
Tubes can cause radio to be dead, weak, in-
termittent or distorted.
Before checking tubes, make sure that they
are all firmly pressed in sockets. Tap each tube
with handle of light screwdriver with volume
control wide open, and replace any tube that
causes noise in speaker. Replace tubes, one at a
time, with tubes known to be good (allowing
about 45 seconds to heat up) until the defective
tube is found.
c. Fuse and Vibrator
If
vibrator does not start when radio is
turned on, check the fuse. If fuse is blown it
indicates a sticking vibrator. Install a new fuse
and check vibrator for sticking as described
below.
If
fuse is not blown, or vibrator does not
start after a new fuse is installed, remove re-
ceiver cover and tap the vibrator. If vibrator
starts after tapping, or after installation of a
new fuse, let it run for about 15 minutes and
then check for any tendency of vibrator to stick
by turning radio on and off repeatedly.
Replace the vibrator if it will not start or has
a tendency to
stick.
Replace vibrator if it buzzes
unevenly or is exceptionally loud.
d. Wheel and Tire Static
This noise is electrical charges collecting on
the wheels, then discharging to the road sur-
face through the tires. The surface of the road
determines the strength of discharge. Wheel or
tire static very seldom occurs on gravel or dirt
roads. This static in mild form shows up as a
click in radio and increases with speed. Apply
brakes lightly and if noise decreases check front
wheels to see that static collectors have been
properly installed and make sure that all grease
has been wiped off
contacts.
In certain cases of
wheel or tire static,
these
static collectors alone
may not completely eliminate all noise from
this source.
Static Eliminator Powder, available through
CM.P.D. warehouses under Group 9.674, may
be used in cases where proper conditioning of
static collectors does not remedy tire static. An
injector for installing the powder is also avail-
able under the same group number. This pow-
der equalizes the positive and negative charges
developed by the tire, thus neutralizing the co-
rona effect and eliminating radio interference
difficulties from this source.
e. Radio Noise Caused by Generator
The sparking of the generator brushes will
produce a noise in the radio which increases
with speed. This noise is identified by a high-
pitched whine. Check generator capacitor to see
that all connections are tight and that paint
under capacitor mounting has been removed.
If
these are in good condition replace capacitor
with new one. Remove generator cover band
and observe sparking. If this is excessive, check
for open armature.
f.
Ignition Interference
The car hood must be closed and securely
latched when testing for ignition interference.
Ignition interference should not occur if the
distributor suppressor and the coil capacitor
are properly installed.
The distributor suppressor must be installed
at distributor end of coil to distributor high
tension wire; installation at coil end of this
wire does not give satisfactory results. The coil
capacitor must be firmly attached to mounting
bracket with clean metal ground contact, and
the lead must be attached to battery terminal
of coil.
Make sure that all high tension wires are
firmly pushed into socket in coil and distributor
cap.
Make sure that the antenna trimmer screw
plug button is installed in receiver cover. See
figure 11-1.
Check the bond strap on the water tempera-
ture gauge tube to make sure it has a clean
tight connection to the dash.
Check lead-in wire where it is fed up through
hole in center of instrument panel to make sure
that it is properly installed and grounded. See
figure 11-7 or 11-8.
If
the items mentioned do not reveal the cause
of ignition interference, replace distributor sup-
pressor and coil capacitor, one at a time, until
defective unit is found.
11-3 RADIO ADJUSTMENTS-ON CAR
When making the adjustments described in
this paragraph it is desirable to have the car
in a location that is as free as possible from
outside interference.
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