INSPECTION
| Symptom | Repair order |
|---|---|
| No power coming in. (No display and no sound from speakers) | Check the fuse and power supply for radio. Check the radio ground. Remove the radio for repair. |
| A specific speaker does not operate. | Check the speaker. Check the output circuit between radio and speaker. |
| Radio generates noise with engine running. | Check the radio ground. Check the generator. Check the ignition coil. Remove the radio for repair. |
| Volume is low in AM and FM modes or interference noise occurs. | Check the antenna. Check the antenna amplifier. Check the noise suppressor. Check the radio ground. Remove the radio for repair. |
INSPECTION PROCEDURE
Measure the resistance between the antenna terminal and each antenna wire.
If an antenna wire is OK, resistance will be less than 1 ohms. If an antenna wire is broken, resistance will be more than 1 Mohms.
Note. When checking the continuity, wind a piece of aluminum foil around the tip of tester probe and press foil against wire with your finger.
Identifying Tester Probe And Pressing Aluminum Foil. Scheme 4
To locate the broken point, move the probe along antenna wire.
Probing Antenna Wire. Scheme 5
Scheme 6
- Clean the antenna wire and surrounding area with a cloth dampened by alcohol.
- Paste a thin masking film on the glass along broken wire.
- Apply the conductive silver composition (DUPONT No. 4817 or equivalent) on the broken portion with a drawing pen. (Scheme 6): Pasting Thin Masking Film On Glass Along Broken Wire
- Dry out the deposited portion.
- After repair has been completed, measure the resistance in repaired wire.
Measure the resistance of antenna amplifier.
Identifying Antenna Amplifier. Scheme 7
- Inspecting for Poor Insulation (shorting) of the Cord Crimping TERMINALS REFERENCE Terminal No. Standard 1 and Amplifier body 10 kohms or more 2 and Amplifier body 10 kohms or more 3 and Amplifier body 10 kohms or more 4 and Amplifier body 10 kohms or more
- Check antenna amp
Disconnect each connector, then measure the direct current value at the above locations using the tester checker.
Standard: (+B = 13.5 V) --> 50±10 mA