28-09-2013, 10:43 AM
Hi Rob I've repaired quite a number of Fender guitar amps Bassmen and Champ's of that era. Some with hum turned out to be the fibre board they're built on becoming leaky, leaking ht where it shouldn't be. After the usual checks have been done, as has been pointed out, electrolytic and coupling caps, any residual hum if its at the front end, then lifting the input components from the board can cure it. Otherwise its a complete rebuild preferably on tag strip more point to point.
Dave.
Dave.







