I've an old Ashdown 65W combo amp that died on me about 15 years ago (it's probably about 20 years old).  I stuck it in the loft thinking I'd one day get it repaired and since I've recently started getting into making my own pedals, I thought I might have a crack at it myself. When it went it made a popping sound and then just wouldn't switch on.  I opened it up and there doesn't seem to be any visible damage.  I can't see any blown capacitors or anything.  There was a 500ma glass fuse that