If anyone is familiar with the quirky and very loveable EG-5 cassette guitar, they would know that one really disappointing feature of it is that both the Guitar audio and Cassette audio and Aux In audio all come out of the jack labeled "guitar out".
You would think that only the guitar would come out of the guitar jack, and the cassette audio, Aux input and also the guitar out (ie. the mix) would come out of the headphone output jack. Sadly, this is not the case; both the cassette output AND the Aux input AND the guitar output come out of this guitar out jack, and while you can turn off the guitar volume out of this jack, you can't turn off the cassette volume or the Aux in volume from this jack without turning everything off.
This has the effect of destroying any chance of using the Aux input as an external effect loop input from the guitar out jack. If you plug the guitar output into an effects pedal, then run the effects pedal output back into the Aux input (so you can use the internal guitar speaker and amplifier for total portable sound instead of an external amp) you will get a feedback loop as soon as you turn up the guitar mix volume.
I have fixed this issue in my EG-5 by tapping in an output cable from where the guitar signal enters the guitar mix volume control on the circuit board, and installing a small output jack on the guitar. So when you play the cassette and something into the aux in (effects unit) and also the guitar, the only thing that comes out of this new jack is the guitar signal (including the built-in distortion sound).
Now, when you run the output of this line into an effects pedal, and back into the Aux in socket, it no longer gets a feedback loop and you can get the effected guitar volume from the built-in speaker as loud as you like!
It's easy to do, you just tap a shielded cable into where the input to the guitar mix slider pot connects to the circuit board (easy to see when you take the back off the guitar) and the shield goes to any earth point on the guitar (one is also on that slider board solder point) and then just solder a mini-jack to the end of this lead, and that's it!
