losthighway wrote: Thu Oct 27, 2022 1:58 pm
Dr Tony Balls wrote: Thu Oct 27, 2022 9:10 am
I agree with both answers, FWIW. The fuse is there to protect the big stuff from getting killed due to a failure. So something has gone wrong and you need to figure out what it is. This will mean replacing the fuse and attempting to turn it back on, but with parts removed to try and trace out what the problem is/was. This would, *generally*, mean removing all of the tubes and turn it back on. If the fuse pops, its something internal that has failed, if it doesnt it was a bad tube that caused the fuse to blow initially. Start reinserting preamp tubes and turning it on to see if the fuse blows. If you get all the way through that, start inserting power tubes (in pairs, into the correct sockets) and testing till you find what makes the fuse blow.
This method will likely result in one going through more fuses than they need to. For repeated use without wasting fuses, use a lightbulb limiter to show when the amp is drawing too much current. Google it to build one, very easy.
Also Tyler's point about which fuse will help to further isolate the problem area!
Excellent advice. Clearly written, thank you.
It's the fuse found on the front of the amp near the power and standby switches.
Months later update:
I used the above strategy and concluded fuses were blowing with and without tubes- an ominous sign.
Our bass player finally got it to a tech:" blown caps, needs new inductor eqs, some tubes went bad". I can't help but wonder if this catastrophe is due to poor impedance matching with a cab, a bad speaker cable, or how one bad part could blow up the chain before the fuse shut it down.
It's like when a nice car breaks down: I want answers. I'm thinking it wouldn't be unheard of for him to take the 16ohm output and plug it into our 8ohm cab, or use a guitar cable for a speaker cable.
Dude is thinking of joining the solid state persuasion.
