Am 27.08.2012 23:17, schrieb Jacopo Sinigaglia:

> Today I was doing "circuit bending" on my 707 ... okay ... but at
> some point, without that touched the circuits, the roland was turned
> off and one is no longer powered back .... some of you can tell me
> something

Is everything "off" (no LEDs, even any noise from the output)

First check whether th powersupply is ok.
Measure the voltage at the low voltage plug of the wallwart, without
beeing connected to the 707.
Then connect it to the 707 and measure the voltage inside the 707 at the
socket.
Then measure the voltages at the various supply voltages at the busses.

Florian