Since fitting the Emerald K6 ECU, coil pack and electronic ignition trigger wheel, my Tacho, (RVI type) has not worked. Having tried all the usual alternatives, finally contacted Emerald. Karl advised that if I wired the original Tacho coil +12v feed wire directly into the +12v input on the coil pack then it would work. I now have a fully working Tacho. Cost nothing to do and retained the original clock internals. I made a short video of the work required for anyone else struggling with the same problem.