How to Fix Car Radio Static

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Q:

Here’s how to test for a bad diode with nothing more than a decent digital multimeter.

1. Set the meter to read “AC VOLTS” (lowest range).

2. Connect the black “COM” lead probe tip to the battery negative post.

3. Connect the red “VOLTS” lead probe tip to the battery positive post.

4. Run the engine at 1500 rpm.

5. Turn on the a/c and rear defroster.

6. Your meter reading should not exceed 0.09 volts (90 millivolts) AC.

You can replace the diodes in the alternator fairly easily, or just swap in a rebuilt alternator if one is available fairly cheaply for your car.

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