7.5A PCB power fuse keeps blowing
2003 Signature. Replaced Big Boy solenoid a couple weeks ago because chassis batteries weren't charging. All has been good for a couple weeks, including a week-long trip. Got home for a day or two, and noticed the little green light that indicates the Big Boy is functioning is off, and chassis batteries are not charging again on shore power or generator power. House batteries charge fine. I checked the fuse next to it; it was blown. I went to replace it, but as soon as the new fuse touched the contacts, the fuse blew. I turned off the big main switches to house and chassis batteries, and shut off shore power, and replaced the fuse, but as soon as I turned the switches back on, it blew. The inverter seems to be working normally. My wiring schematic that came with the coach doesn't even show the board or fuse in the rear run panel. Suggestions on where to look next?