Somehow I feel, that this should not be necessary, but experience shows that this WARNING is absolutely needed over and over again…
All my projects are working with high voltages. 230V AC mains or even over 500 Volt DC voltage in tube amplifiers. These voltages does not only hurt like hell if you touch them, they can be lethal as well (depending if your body is making a nice current loop)
Advise is to be extremely careful, check and double check what you are doing. Often forgotten: high voltage capacitors typically carry high voltages for hours.
Old HINT: when working in a “life” amplifier, always put ONE hand only in the chassis, the second hand on the table or better behind your back. This will the limit lethal danger somewhat because you are not creating a close current loop between your hands (AND…. your heart is in between them). Still you can get a nice shock though…
Last hint, try to be a high impedance to any ground (no foot on the heating pipes as it is nice and warm. No bare feet on the floor etc etc. I have a rubber mat under my chair and I wear shoes with rubber soles. That helps also. And believe me, still than a shock is very unpleasant …. (yes I have been not paying enough attention as well at some point, but at least I was prepared as I describe above)
Finally, images speak a thousand words….. I like this picture, it takes the seriousness a little bit out of it – but still very to the point !!
So, enjoy our hobby, but try to stay healthy and alive !