Help! Luke 3 Output Jack Wiring

[silence.speaks]

Just had a frustrating experience trying to change my L3 output jack. I got a stereo barrel jack and connected the wires just as they were in the old jack, white to tip, green to ring, and the black bundle to ground. But when I fully insert my guitar cable into the jack there is no output, like it's grounding out. But if I barely pull on the cable the guitar output comes alive.

Can anyone enlighten me? I've got a multimeter and with the cable out everything is open but with the cable inserted I have continuity between tip and ground and open between tip and ring.

 

[DrKev]

First, try a different cable. Different manufacturers have slightly different sizes and tolerances in the dimension of the cable ends and barrel jack plugs. Changing the cable may be all that's required. It's rare but frustrating.

 

[stefan.hoehn]

I hit me two. I finally found out that the way it works and the wiring is as follows:
- all blacks go to the ground pin
- the white one goes to the pin that ends at the tip of the male connector that is put into the jack (the smaller one "near to ground" - kind of in the middle of the jack)
- the green usually goes to the small pin next to the white but I found out that it works on either of the other two pins (the fourth on the outer side seems to be an optional ground, at least the resistance between the main ground and this one is pretty low).

The way it works is that if you connect the ground and the white only, you will not get a signal output. Only if you touch the green cable to either ground or the signal "magically" the circuitry is switched on and you get a signal (it needs to stay there though, otherwise the circuitry goes off again to save battery). This seems to happen when you slide the male connector into the jack which IMHO creates some "spike" on that cable.

This by the way explains why you should not keep you guitar connected all the time as it will drain the battery.

Correct me, if I am wrong.

 

[beej]

What's happening here (and on all of the MM guitars with a battery), is that the negative connection from the battery is disconnected from the circuit ground, so that no current flows through the circuit.

Once you insert a cable, the negative from the battery is connected to circuit ground via the sleeve of the jack, effectively turning on the power switch.