Intro: How to Fix a Speaker With a Broken Knob
Nothing lasts forever, we all know that. However, when something breaks, most of the times you can fix it.
In this instructable, I will detail how to fix a speaker with a broken potentiometer or knob. Clear sings of a broken potentiometer are a speaker or a bass that does not work properly normally; yet when you push or move the knob, springs back to life.
In my case, the speakers were Maxell's Mblast 2.1 speakers, although the process is virtually the same for all speakers. The bass control knob, the upper one in the picture, is the broken one.
To make my terminology clear, the decorative knob refers to the plastic knob you hold, the potentiometer refers to the electronic component underneath that is malfunctioning.
Step 1: Tools
You will need
-A soldering iron
-A desoldering pump or desoldering wick (One of the two)
-Solder (electronic grade, not plumbing grade solder.)
Step 2: Remove Covers
The first step is to expose the potentiometer. Depending on the speaker, the cover may be either glued or screwed. If it uses screws, its just a matter of removing them; if it uses glue, you're pretty much limited to buying new speakers.
Often, the screws will be hidden somewhat. In my speakers, the screws were hidden by an external cover that was held by a pressure fit.
After removing it, six screws were visible, point at which I could separate the cover from the rest of the bass. the decorative knobs are held to the potentiometer (the real broken knob) by mere pressure, just yank it hard.However, on other models, there might be a central screw, be sure to check that out first.
There is usually a nut under the decorative knob that will prevent you from separating the circuit from the main cover; make sure to remove it if it exists.
Step 3: Removing the Old Potentiometer
Using either the desoldering pump or the desoldering wick, remove the broken potentiometer. You will now need to obtain a similar or an equal one.
How to get an equal one: usually the potentiometer will have a value marked somewhere in it, such as 20k, or some other value. If it does, just go to a local electronic (or order it through Internet if you cant find one). A bass potentiometer is easy to find, a volume potentiometer may be harder to find, but everything can be found online.
Just make sure it has the exact marked value. If the old potentiometer does not have an marked value, measure the resistance using the multimeter between the right and left leg; the middle one is usually the one that fails. Then, as above, get one with the value closest to the measured one.
Step 4: Solder the New Potentiometer
Now solder the new potentiometer. How to solder is outside the scope of this instructable, but others have surely covered this topic. "Curious Inventor" also makes great videos on how to solder, I recommend you to Google it if you haven't soldered or unsoldered before.
Then, start the process of reassembly. If your potentiometer had any nuts that kept it attached to the enclosure, be sure to place them before inserting the decorative knobs over the potentiometer.
Step 5: Enjoy
Need I say more?