short circuit when clamping core J5 vss to ground

[SounDuke]

When I connect J5 Vss to the chassis, I experience a short circuit. I'm pretty sure this is because of a component, maybe you can help me tracing which one is it? The weird thing for me is that when I do not clamp Vss to the chassis everything goes ok, woltages too and the pic runs without problems except that the 8 pots connected to J5 send occasionally random midi data when I turn them.

[SounDuke]

Solved this one too.

Better not tell you the reason of that short or Thorsten himself would solder my butt together :D