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Permalink Reply by David L. on November 11, 2016 at 1:35pm

If you look at my late night too knackered to use more than black ink drawing attached.

Most battery preamps have two wires going in to the preamp - usually from the included rod piezo that has the silver braid earth wire wrapped around a central live wire hidden inside.
Coming out you have the live wire (usually red) going to the Jack socket and soldered to the lug in contact with the tip of an inserted Jack plug. Also you have the common ground wire (black or silver braid) going to one of the lugs that the Jack plug shaft touches.
The preamp then needs power so the battery + goes to the preamp. The battery negative is soldered to the spare lug on the Jack socket which will also touch the shaft of an inserted Jack plug(so long as you are using a stereo Jack socket).
In this way plugging your guitar in turns the preamp on and once finished pulling the plug out turns it off. In reality it is also why the preamp battery is often dead because it is real easy to forget to unplug :0)
Wiring colors might be different because imported guitar electronics sometimes use different colors than expected (but I think yours will be as above). To be real sure if you insert a plug into the Jack you cut off you will be able to see if the red touches the tip.

Regards,
David L

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Permalink Reply by lawntrout guitars on November 12, 2016 at 2:47am

THANKS!! 

Thats exactly what I needed. I couldn't figure out what that third wire was all about.The jack is basicly a switch.  It never occurred to me to connect the braid to the white negative .

Great diagram

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Permalink Reply by Fomhorach on November 13, 2016 at 2:02pm

Have a look at the orig jack and just copy it if it's the same.

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Permalink Reply by JL on November 15, 2016 at 5:30am

On a pre-amp, the jack is usually a 3 contact jack, aka Tip-Ring-Sleeve aka stereo jack left-right-ground.

connecting the battery negative (-) to the ring (stereo right) and the pre-amp board's power negative (-) to the sleeve (along with all the other ground connections) lets you plug in a mono instrument cable (tip-sleeve) and since the sleeve of the cable's plug touches both the ground and the ring it completes the circuit to power on the preamp.

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