Got an old Carlsbro amp, has been good as gold until the other night when it shut down. Checked the fuses, and sure enough, the HT was fine but the mains had blown. So, I get a new fuse and pop it in there. Get power for about a second or two and then the fuse blows again. Have tried multiple fuses, still the same results.
does the fuse still blow with the power tubes removed?
if it does not blow you might want to change output tubes, if it does still blow you could suspect a shorted diode in the power supply. anyhow from what you have described, I would suspect a shorted diode.
what size fuse is the HT?