Antenna Feeder

INSPECTION

1. Check the continuity between core cord. If there is a continuity between both ends, the core cord is good codition.

Fig. 13-248

2. Check the continuity between sealed cord.

If there is a continuity between both ends, the sealed cord is good condition.

TROUBLSHOOTING (RADIO)

1. Description of symbols

Inspection item

Check or replace part

For the connector, refer to the wiring diagram and check for short circuit or open circuit. Also check the connector for separation or improper contact.

Pass if not necessary

Adjust

Test by operating radio

Wire harness

2. Dead radio

(1) No noise whatever Cause:

1. Blown radio fuse

2. Disconnected power source connector

3. Blown main fuse

4. Broken speaker wire or disconnected connecor

5. Defective radio

Adistinct Click

Power switch on and volume control maximum.

Power switch on and volume control maximum.

Fig. 13-250

Fig. 13-251

Fig. 13-252

Fig. 13-252

Turn radio to maximum volume. Switch the radio off-if a sound is:

Heard

Fuse probably blown

Not blown

C Radio")

| Not heard

When switch is placed from ON to OFF.

Heard

Refer to 2-(2) There is static but no AM or FM broadcast.

Check for 12V current at receiver power source.

Not blown

-oose speaker\_ v^connector J

-OK

No

Measure resis

Approx. 4Ü /

tance in speaker

(Fig. 3-252) * ^

0 or oo

(Speaker^)

(Speaker^)

(Radio)

A steady hum may come from the transistor, resistor, condenser and coils of a radio.

Fig. 13-253

Fig. 13-253

Fig. 13-254

Over 1 Mil

Fig. 13-254

Over 1 Mil

reception. Cause:

1. Disconnection or improper contact of antenna plug

2. Broken antenna wire

3. Defective antenna

Can receive AM with the antenna at full length and volume at maximum. A piece of metal touched to the antenna causes a grating sound.

Remove radio

No problem

Check resistance between antenna plug and ground. Over or under 1 M H

Over

Over

Check to see if antenna plug is loose or disconnected

Problem

Antenna plug J

Under

^Antenna)

Check resistance between antenna plug tip and pole tip. Over or under 5il

Under

(Antenna)

Below 5il

Fig. 13-255

Below 5il a

3. No Reception of either AM and FM (If antenna is for both AM and FM)

Cause:

1. If there is no AM reception, radio receiver is defective.

2. If there is no FM reception, radio receiver is defective or there is no receivable FM signal in the area.

The range is the maximum radius wherein of a radio signal can be received. FM range is limited, the signal rapidly decreasing at its maximum range. FM signal is also line of sight so there are valleys behind tall buildings, mountains. In this respect, FM is similar to television.

4. Faint reception Cause:

1. Improper adjustment of antenna trimmer.

2. Defective antenna

3. Defective speaker

4. Defective radio receiver

Reception with the antenna fully lengthened, however, faint with:

Faint static

Install another radio reception temporarily. The reception is:

static Removal

\ of radio

static Removal

\ of radio

Same

)

No

Resistance between

antenna plug and

. (

ground is over or

Over

under IMft.

(Fig 3-254)

tenna

tenna

(Radio)

Fig. 13-256

Fully extend the antenna.

Set the dial at about 1,4000 kHz.

Fully extend the antenna.

Set the dial at about 1,4000 kHz.

AM set

Volume at maximum

AM set

Volume at maximum

1. Fully extend the antenna.

2. Set the dial at about 1,400 kHz, volume at maximum.

Fig. 13-257

Fig. 13-257

3. Adjust the antenna trimmer so that the radio hum is loudest.

5. Hum is irregular

(1) Hum is irregular on AM or on AM/FM

1 Check to see if the I hum is occasionally ■ Always irregular or always \ irregular

Remove" radio ,

Temporarily install another radio.

The hum is:

Occasionally

'Sound is or is not irregular near antenna of broadcast-jing station

Not irregular

'Sound is or is not irregular near antenna of broadcast-jing station

'Excessive^

antenna

power

1. Broken speaker cone paper or foreign matter is lodged next to it

2. Speaker voice coil and magnet in contact

3. Excessive antenna power input

4. Defective radio receiver

Irregular

Cord contacts speaker cone paper.

Irregular

Replace speaker or remove foreign matter

Cord contacts speaker cone paper.

Not irregular

Remove speaker and check for ripped cone paper and/or entry of foreign matter

J Speaker voice coil and ! magnet in contact

Replace speaker or remove foreign matter

Replace speaker

—^Speaker damaged at time of installation^

Fig. 13-258

Near a broadcasting station the sound on any radio becomes irregular because of excessive signal power. This cannot be avoided in most cases.

(2) Sound is irregular on FM only

Cause:

1. Improper tuning

2. Defective radio receiver

1. Multipath is a multiple reflection. Signals from the broadcasting station antenna reach the receiving antenna after having been reflected by buidings or mountains as well as by direct contact.

They interfere with each other. However multipath changes over time or by moving the place or reception. With multipath reception, voice endings are unnatural.

2. With FM, improper tuning results in irregular sound. Pay special attention to tuning.

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