I bought an old 1961 Magnatone 425 bass amp which had been chopped and turned into a head last year and finally got round to trying to get it working again on Friday. By some miracle or other - after rebuilding the whole of the power amp which was a complete mess, and replacing all the 220K plate resistors and a couple of pre-amp caps - it works! I was planning on selling it but it sounds so bloody good I'm going to keep it - I don't think they're worth much anyway.
The only remaining problem is that there is quite a lot of hum. I'm in the middle of doing all the usual stuff to get rid off this (and it seems it's the grid lead going to V1b, or maybe the star grounding scheme), but I've noticed there's an anti-hum switch in the schematic. This has been disconnected, so I'm wondering if it's unsafe by modern standards. Is it safe? Might it help? Here's the schematic...
Comments
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein