And just to string this along a little, and to maybe clarify a misconception, there is no voltage stored in a tube. There can and usually is a lot being applied to that tube from the capacitors (which do store power) in the power supply. Those capacitors are doing just what they are supposed to do, nothing wrong with them. And just like people, even when you stop feeding them (turn the power supply off), it can take a while to get rid of what they have already been fed, sort of. Putting your fingers in that "discharge" can make you very, very unhappy, so don't! Even if you live over it, it's a real 'crappy' experience.
Discharging high voltage requires that the 'hot' conductor should be grounded. The chassis ground is usually where that grounding is done. The 'biggy' is to use something that is insulated, has an insulated 'handle', to do that grounding. An unused (or maybe over-used) screw driver is the most common tool used to do that. There is also a definite 'order' in making that ground connection! Touch the chassis ground (and KEEP that contact), THEN touch the plate cap(s) of the tube(s). Do it the other way around means you will probably get a very nasty surprise! And just to be sure... do it again. It's fairly common to hear and see when that discharge occurs, snap/bang/whatever, maybe even a bright spark. And if you are as 'chicken' as me, you'll wait a minute or two and do it again just to make sure, sort of. That stuff really does bite! It's also a sort of good idea to keep one hand in your pocket while doing that discharging, but don't 'hold' anything in that hand while you're doing that. Muscles contract when subjected to electricity and can produce some interesting results, sort of.
Hey, it's your neck (or other anatomical parts), treat it like you want it to be treated.
- 'Doc
Have I ever... Just once with a 6146, which has quite a bit less voltage than typical final tubes, and I will absolutely guaranty I will never do it again! No, I wasn't 'holding' anything... thank goodness!