Hello, I have the exact same omnivibe but the volume decrease button did not work ( i bought it from a thrift store for 6$ for the electronic components inside but found out every thing worked except the volume matrix! ) anyways i pulled the sticker off the vol + / - and power bar to see what it looked like and it is just a simple two wire sensing pad. Heres what i did to fix mine - keep in mind that there are three possible reasons for your volume button not working:
1) the ribbon cord thingy with the metal strips inside the stereo makes the electrical connection from the sensor to the "mother board?" is damaged and not able to read that your pushing the button,
2) the connection from the ribbon to the 4 prongs directly on the mother board thing is loose/ damaged or dirty/dusty somehow and
3) the connection from the metal plate on the bottom of the sticker covering the volume + button that touches the wires underneath is dirty or faulty some how.
There is also the possibility that the "motherboard" is damaged but if the other buttons work then thats probably not the case, any way on mine the problem was the ribbon cable strip thing so i cut it off and made my own push button system that i will tell you how to make your self. ( you can do it my way which uses pushbuttons for all three of the ones on the iPod dock or you can just wire in one for the volume + but that way is harder and its a matter of time before the other two buttons go any way)
Materials needed - soldering iron, 3 push buttons from an electronics store ( small ones are better so they fit where the old vol +/- and power buttons were) some wire - 20/22 gauge solid wire, a drill and a bit thats the same size as your push buttons.
Step 1- take the screws out of the back so you can get at the insides- theres a hidden one behind the sticker with the all the warnings on it telling you not to take it apart! ;)
Step 2 - take the circuit board out and be care full not to touch any of the round capacators ( they look like little barrels) cuz they could shock you even after you've unplugged the stereo - which i hope you have already done!
Step 3 - unscrew the iPod dock from the back of the stereo case and peel the sticker off of the top - the one that says vol+/- and power - check to make sure its clean underneath, if it is then check the ribbon coming out of the bottom of the dock ( the flat wires you can see under the sticker go to the ribbon ) and see if there are any breaks or scratches or anything that looks like damage - if thats ok then pull the ribbon connection off of the circuit board and make sure the four prongs and ribbon connection are good- if all this looks good then clean prongs with a rag or something and put it all back together and see if it works now, if any of that is damaged or it still dose not work then you will have to build your own volume and power control buttons which is what i did... and heres how...
1) take everything apart again ;) and drill three holes into where the vol + and - and power buttons were, make sure u don't drill into anything else like the red and black wires that are also there - you don't have a remote anyways so cut those white wires off that go to the remote sensor to make life easier and disconnect the speakers if you want.
2) cut the ribbon thing off as close to the iPod dock as you can and disconnect the black clip thing from the circuit board - it just pulls off but do it gently
3) remove the black clip from the ribbon - see the 4 holes in it that you can see silver tabs in? push those holes onto the 4 prongs and slide the ribbon out gently, you will then see 4 silver clip things attached to the metal in the ribbon - take those off gently so you can solder new wire onto them and reconnect to the prongs later, keep that black clip too!
4) OK now the fun part! cut 3 pieces of wire about 6" long and solder each one of them to each one of the terminals on the pushbuttons, cut another piece of wire about 6" and then 3 jumper wires that are 4" each, solder the three pieces together on one end so that you have 3 wires going into one and then solder that to your 4th 6" wire like this...
5) Now solder that piece to the other terminal on the pushbuttons and you should have 3 pushbuttons all hooked up with 4 wire ends showing - remember those silver clips you cut off of the ribbon? u have to solder each wire end onto the end of each one of those - this is a bit tricky but doable!, when thats done place each silver connector into a plug on that black clip you took off the ribbon, the order is shown in the diagram - its not too important for the buttons but the top pronge on the circuit board is the one that must have the 3 to 1 wire attached to it the prong under that is volume + then power and the last one is Volume -, Now you should have something that looks like this...
Sorry about the crude drawings but it is the easiest way to show!
( where it says black clip with an arrow there should also be 4 holes where you pushed the old ribbon clips out from )
6) Well the hard part is done!! alls thats left is to place your push buttons up through the holes you drilled earlier, you can put them however you like i.e.- power then volume down / up or what ever- i hot glued mine in from underneath cuz i drilled to big but hopefully you can screw yours on properly depending on what push buttons you got.
7) Now connect your black clip with all the wires into the prongs on the circuit board - make sure your in the right orientation with the three to one wire being in the top prong ( the one furthest away from the dock) and the 4 holes in the clip facing out.
8) Now put everything back together and plug it in and test out your new home made push button matrix! if it dosnt work then you will have to check your wiring and soldering again.
I truly hoped this helped ya out!, i spent about two weeks figuring this one out and in the end i built a new box to house the speakers and circuitry so it would look cooler, but the pushbutton matrix is much more reliable and durable then the one that was installed originally!
Enjoy and Good Luck!
