I noticed a issue on my 1981 RD100 112....GD-2A circuit...when the amp is in standby I can still get sound out of the speaker, but it is most noticably on only the low 'E' string when strummed/plucked around the 5th and 7th frets...less or no sound anywhere else on the fret board or on other strings. The sound is muffled and distorted but certainly noticeable.
I am thinking that the diodes in the main filter are leaking a bit of voltage through to the power tube plates section and allowing a bit of signal through to the speaker.
Any other possibilities or suggestions?
I replaced the main electrolytic capacitors a while back, but I did not touch the resistors or diodes under the "can" or from the tubes. I am thinking to go back and fully replace all of those components... but if that is not the likely source, I will forego the effort. The sound is not a problem, just unexpected.