Seeking help identifying acoustic preamp output wiring

[Aaron Howell]

I have a Yamaha CPX-15 in for repair. The owner allowed the strap button/jack to rotate enough that it ripped out the four wires from the output jack. I've searched high and low to find a schematic and have come up empty handed. Wire colors are Red, Yellow, Green, White. If anyone can help, I'd sure appreciate it. Thanks.

[Len Biglin]

Hi Aaron , The 3 wires are 1, the output . 2, ground . and 3, battery negative . The battery wire connects to the extra (ring) tab and so gets grounded when you plug in a mono guitar lead , so then the system is turned on. Take a multimeter and find which wire is -9v compared to the other 2, or just which connects direct to battery neg. clip.

Plug a guitar lead from an amp into the endpin jack , touch the tabs to find the noisey one , thats where the output connects , The ground is usually a larger tab and the ground wire is usually a braid encasing the other wires . If you can't sort it out give us a picture or 2 .

[Aaron Howell]

Thanks for the reply, Len. This one has me stumped as there are 4 wires. I do know the yellow wire was the only one left attached (to ground) when I got to it. I'll upload a picture tomorrow.

[Len Biglin]

Oh sorry about that , I was speaking in generic terms which would cover 98% of tailpin jacks . I will see if I have any Yamahas in my junk pile to check up .

[Ron Ellison]

The CPX 15 has a piezo pickup and a mic. Perhaps the extra wire is for one of those. This page has some data under the Support tab

http://usa.yamaha.com/products/musical-instruments/guitars-basses/e...

[Aaron Howell]

Thanks for all your input, fellas. Ron, I'd already scoured that page and sadly, there's nothing there to answer my question. I did however, determine the green wire is connected to the negative battery clip. That, coupled with the yellow wire being connected to ground, leaves the red and white presumably as the pu and mic outputs. Wired it all up, and nothing. I suppose I could try and contact Yamaha...

[Len Biglin]

I have just met with a preamp on a K Yairi , which seems to be a yamaha rebadged , it has black - output , red and white must be connected to turn on , and then plain braid as ground . However the battery wire is positive not negative . But perhaps you can try connecting 2 wires , and have the other 2 as ground and output .