As long your PIC is really floated (there is no leackage current to the earth) it must run perfectly even the hot wire of the AC line is connected directly with any PIC input or PIC supply. How looks your AC to DC converter ? SMPS, transformer, capacitor based ? What means in your language "solid +5V". Have you measured the +5V ripple with a floated scope ? Maybe is swamp there. Vasile On 6/17/08, Estevan wrote: > Folks, > > I have a strange problem here. I have an AC to DC converter circuit that is powering a PIC16F873A that is connected to a 2x16 LCD. When the unit is connected to the AC line (US 60Hz) the PIC does not begin it's program (LCD has nothing but bars). The +5V regulator has a solid +5V, but as soon as I unplug the AC cord the program begins to run (large filter cap) until the filter cap discharges (LCD displays prompt). Could this be from the 60Hz noise causing problems or ... ? Any ideas, recommendations or "magic" pointers out there? > > Thanks ahead of time! > > Estevan. > > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist