Thank you for a respectful and intellegent answer, RP. Exactly what I needed to know. We all have to start some where, right? Unbelievebly.... I was given a DT-50 that has an issue (hopefully only 1 or 2). I installed a new pair of EL34's and they both began to redplate (glowing plates) within about a minute after switching from Class A power to Class A/B power.
I found a blown F2 fuse and replaced it. I had and old pair of EL34's that I put in it when I got it home, and it appeared to be working good on all settings. So, I thought..... "hummmm, maybe I got lucky???". So... I ordered new tubes, installed them and they both began to redplate within a minute. So..... I shut it down and let it cool, put the old tubes back in.... and now it works again, without redplating??????????????????????
I'm hoping someone out there has some knowledge in this area and might point me in the right direction. I'm suspecting maybe a cap in the bias section (if this thing has one?). Anyway, any help would be greatly appreciated.
I feel bad Toneman. I just wondered what that button did.... now I know.