I have the same problem with the 6 zone. The power transformer is putting out 29V AC to the power board. The power board has a fuse. It looks like a yellow capacitor but it is a fuse. You may want to check that. Mine was not blown. I have purchased a replacement powerboard on eBay for $19 and am waiting for delivery. I am guessing the board is bad since I cannot find any data on troubleshooting the power board. I will let you know if it fixes the problem… if it doesn’t I am anticipating having to purchase a completely now unit.