EHX Tube Zipper blowing mains fuse

[AJStrummer]

Hey All.

Have a Tube Zipper I'm trying to repair. Seems to work ok with no connection to input or output. As soon as there is a jack inserted, the mains circuit breaker trips on my workshop!!. It only requires 12VAC which I'm supplying from a Variac and checking on my DMM (original PSU not supplied). A transformer steps it up to 250VDC to power the AX7's. I notice that there is continuity to ground from the jack tip once inserted to input. This doesn't seem right to me. Voltages look ok at the tube sockets. Would anyone have a clue as to what might cause this? Schematic attached

TIA
AJS

Electro-Harmonix-Tube-Zipper-Schematic.pdf

[Dave H]

Are you supplying the 12V AC from a variac connected directly to the mains?
It needs an isolation transformer.

[AJStrummer]

Yes I am. Doh!! Better grab one asap ;-))

Thanks

[Enzo]

Or just find a 12v source. Most any AC wall wart with 12-14v would work, at least for tests.