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The most likely reason your CB radio only works when you wiggle the volume knob is a dirty or faulty potentiometer
. A potentiometer is a variable resistor that changes the volume, and over time, dirt, dust, and corrosion can build up on its internal contacts, causing intermittent or scratchy audio.
How to fix a scratchy volume knob
The simplest and most common fix is to clean the potentiometer using a specialized electronics contact cleaner.
What you'll need
- Electronics contact cleaner: You must use a product specifically made for electronics, such as DeoxIT or a similar brand. Do not use harsh solvents like WD-40, as they can damage plastic and leave behind a residue that attracts more dirt.
- Small straw applicator: The spray can should come with a thin plastic straw to direct the spray precisely.
- Small flat-head screwdriver (optional): This may be needed to open the radio's case.
- Small flashlight
- Turn off and unplug the radio. Wait a few minutes to ensure there is no residual power.
- Locate the potentiometer. On many CB models, you can often spray the cleaner into the volume knob shaft from the outside. If not, you may need to open the radio case to access the back of the volume control.
- Spray the cleaner. Place the straw applicator on the spray can and give the potentiometer a small, targeted burst of cleaner. Look for a tiny opening on the casing of the potentiometer and spray directly into it if you can see one.
- Work the cleaner in. Immediately after spraying, rotate the volume knob from its minimum to maximum setting several times to help the cleaner scrub the internal contacts.
- Let it dry. Allow the cleaner to evaporate completely before you power the radio back on.
- Test the volume. Plug the radio back in and test the volume knob to see if the problem is resolved. You may need to repeat the process a couple of times for particularly dirty controls.
If cleaning the potentiometer does not solve the issue, the problem could be elsewhere in the radio's audio circuit:
- Cold or cracked solder joint: Vibration can cause tiny cracks in the solder connections on the circuit board, especially around the volume control or the audio amplifier chip. Pushing on the board can temporarily re-establish the connection. This requires a technician with soldering skills to fix.
- Faulty audio chip: The audio amplifier integrated circuit (IC) can sometimes fail or suffer from bad solder connections, causing intermittent audio. You can check this by plugging a speaker into the PA jack and switching modes to see if the problem persists.
- Loose external speaker jack: If you use an external speaker, the internal switch in the radio's external speaker jack can get dirty or bent. Wiggling it or pushing down on the contact inside the jack might restore the audio.