I'm trying to program a PIC18F2550 with a PicKit2 programmer. I haven't had any trouble programming the device when using power from the USB port, but I cannot get it to work when using an external power supply. I have set the PicKit to be powered from target and there is no voltage across my rails when my external power supply is not connected, however as soon as I connect the negative supply rail (which is connected to earth) my power supply shorts and turns off (before I have connected the positive rail). How do i fix this?
Thanks
Thanks