Welcome to theCarverSite!
We have the Owners Manual in our Library. You can find it in the Manuals and Specsheets section above. Once that page is open you'll see a spreadsheet with tabs along the bottom for the various Bob Carver gear. Select the Sunfire tab and scroll to near the bottom and you'll find the Owners Manual. Unfortunately, most Sunfire schematics are not found in the wild. Your unit should have a 6.25 Slo-Blo fuse in it. If it's blowing instantly when turning on, it could be bad output transistors, bad capacitors, bad rectifiers. There are some You-tube vides that describe the problem you're having, if you're comfortable testing and fixing it yourself. If not, you may wish to have it repaired by Greg at Nelion. He knows Bob Carver gear inside and out and does great work. Good luck!