How do I convert spade terminal volume control to something else??

I removed this circuit board from an old ipod dock I was about to trash but wanted to keep the innards for something. I'm connecting this to some other speakers but don't know how to convert the volume control. Right now there are two silver, plastic caps with a screw in the bottom of them. The screw runs through a spade terminal which is soldered onto the circuit board. When you tap one of the caps it raises/lowers the volume until you stop tapping it. I want to convert this to something different, preferably a volume knob of some sort. I'm not very versed in electronics, just been messing around for a couple years making simple stuff like lamps, etc so please help a noob. Any suggestions are welcome. I'm not even sure this can be converted but thought I'd ask because I'm fresh out of ideas. Thanks a lot. 

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frollard4 years ago
It's probably not too hard;

The touch sense buttons are connected to that chip sc9235 on the right of the pictures.

That's a volume control. The big stuff on the heatsink on the left is the amplifier circuit. So your audio runs through that black chip, then to the amplifier. The chip on the FAR right I can't read, but I bet it's the capacitive touch sensor, providing 2 outputs. The volume control has a stepped up-down input, no pot input, so you'd have to replace that chip with audio grade pots.

To hack into this circuit you need to cut and tap into the pins on the IC. You could leave it in the circuit just with the inputs and outputs cut.

14 15 and 12 likewise input, output and ground for right channel.

Bypassing this circuit will remove the up/down feature and allow just analog connections, however, you'd end up having independent control of the left and right channel.

Alternately, you can tap into the circuit before this chip and use your own up/down inputs instead of the touch inputs, skipping the capacitive touch circuit. Pin 6 is up, 7 is down. Briefly connecting these pins to ground will increment or decrement the volume. Recommend a debounce circuit to prevent multiple accidental hits. Holding the pin low will cause the volume to automatically increment or decrement.

Pin 3 is input for left channel, pin 2 is output, so you'd connect 3 to the wiper and 2 to the out of your audio pot, pin 5 to the
westwaswon (author)  frollard4 years ago
How about something more rudimentary since I'm not so sure about that. I'm thinking maybe a way to rig the volume up so it always stays at max volume and just putting the volume knob in between the speakers and the board. Any ideas on something like that?
That could work, but I outlined how you'd have to hack the circuit to do with the parts at hand. If you replace anything else its easier to get another part.
Those are touch sensitive buttons. You won't be able to replace those with a knob unless you can isolate the circuits that run the buttons and where they output the needed signal to adjust the volume. Then you need to figure out what kind of signal is being sent to the system. Once you know that you can connect a pot to a micro controller and have the micro controller send the required signals to the board based on the position of the pot.

As you can see it will be a very involved project. It would be much easier to convert a set of PC speakers into an iPod boom box. Here is a similar project i did a while back. Its a very basic iPod stereo but it works great. With a little more work i could make it better and utilize all the pins available on the iPod connector. Eventually i'll make another one that also offers features like you can get with a camera adapter cable and AV cable for the iPods.