On Sun, 15 Mar 1998 08:45:25 +0000 Nigel Goodwin writes: >The chassis in a PC power supply should be connected to earth, as >(usually) is the ground connection on a scope. However it's common >practice to disconnect the earth on a scope for safty reasons in the >TV >service trade. Many older TV's have a live chassis (or half live), >touching the chassis and the scope, as you tend to when you are >clipping >the earth lead on, results in a severe electric shock - probably from >hand to hand, directly across the heart!. Also assuming you don't >touch >the chassis as you fit the earth lead, there is an almighty BANG!!, The *proper* common practice is to connect such a TV to an isolation transformer before operating it with the back off. Then a properly grounded scope can be connected to the TV chassis without incident, and everything is grounded. Lifting the scope ground is *not* safe. Another good safety practice is to never touch a live TV chassis with both hands (hold one hand behind your back). Then if you do touch a live wire and get shocked the current isn't as likely to go through your heart. New TVs also often are of live-chassis design. Higher-end models usually use a switching power supply that isolates the rest of the TV, but of course the power supply circuit is live. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]