5F6A Bassman bias help...

[DrGonz78]

I have come across some high voltage selenium rectifiers. Huge things! If one of those failed it would be be like a lethal wet elephant fart that could never be fully dispersed.

[Jon Snell]

I've read this many times. Never experienced it. I hope I never do.

Imagine the smell of rotting mackerell on a bonfire ... that is somewhere near it.
One of my first jobs as an apprentice was replacing old and failed selenium plate rectifiers, in radio transmitters, with STC diodes. The stench of the burnt out rectifiers never leaves you!

[pdf64]

I have a 58 Bassman on my workbench. Changed some dried caps amps is sounding great but one 6L6WGB tube was redplating. I measured and whoah... 88mA on one
…
I know that new matched set must be bought soon, but at the moment I want to make amp just playable within safe limits.
Is there anything I'm missing here? …

Unless proven good somehow (eg in another amp), a valve that’s redplated heavily should be considered irretrievably damaged.
As such, it’s never going to work properly again.
Attempting to mod the circuit to try and accommodate a knackered valve is wrongheaded.

I agree that pre-emptively replacing the selenium bias rectifier with a silicon type would be a good idea.
Also consider adding a bias trimmer.

[The Dude]

The funny thing about selenium rectifiers is that I've seen them go for insane amounts of money on eBay and elsewhere because of the "vintage" aspect. I never have, but if a guy wanted to sell one after you pull it, you could probably make some decent cash from someone "twisted" enough to buy it. IMO, being a preservationist is fine to a point, but some things should just die. For me, purposely installing a selenium rectifier is akin to installing asbestos insulation to preserve the integrity of a vintage home.

Edit: Had to look. Check this.

https://www.ebay.com/itm/35470579033...9-5Yw&LH_BIN=1