Of all the non-PCB tube amps that Fender ever made, the one most likely to rot away unloved in some dude’s attic is probably the Bassman 100. Too wimpy to be a useful bass amp, too loud to be a good studio guitar amp, and too boring for anyone to give a shit about, the Bassman 100 is just begging to be a parts-donor for someone else’s broken Twin Reverb. Naturally, when I saw one at the flea market this weekend, I couldn’t resist buying it.
The seller told me, plainly, that is it needed work; “It hums and buzzes; the guy said it needs a power transformer.” ‘The Guy’ in this case was apparently an electrical engineer who worked for CBS and held several patents? Some kind of electronics genius, I was told? Cum Grano Salis, as the senator said, but I was scared enough that I almost didn’t buy it. Because there are only two parts in a 100-watt tube amp that are expensive to replace: the power transformer and the output transformer. In that case of an 100-watt tube amp as undesirable as a Bassman 100, either of those conditions would make it literally not-worth-fixing. The seller, whom I deal with often, agreed to take it back in a week if I insisted. Fair enough. $140 crosses the table.
As I have commented on before, a tube amp that buzzes and hums is not a bad thing; the fact that it is making sound at all means that at least the power transformer, rectifier, output tubes, and output transformer are working. The rest of the stuff is cheap enough that it shouldn’t be a major deterrent.
I took the thing back to the shop, plugged it in, and guess what: not only did it hum, but it worked, and it was loud. It was loud and it was making bad smells and blowing fuses in 30 seconds also. So oh-keeee… Here’s what needed to be done to get this thing back to ship-shape condition (and no, it did not involve a new power transformer).
This one is gonna be long, and very technical, so please click the link below to READ ON if yr so inclined… (short story: the amp worked great and sounded great after about 3 hours of work and $50 of parts…)