Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: yorgle on November 24, 2020, 09:53:45 am
-
I recently acquired a Tektronix 2225 scope and before I start learning how to measure with it, I figured I should first make sure I know how not to fry it (or myself). I'm faced with the seemingly perennial question of do I need an isolation transformer? I've watched some Uncle Doug's excellent videos and wasted many hours reading online arguments, so I do understand that because the ground clip on the scope probe ultimately connects through the scope to ground, it can make big ZAP if it gets clipped to a hot or neutral point. Therefore, the unit being tested must be isolated from the mains. That makes sense to me if I were to go poking about about inside an old "hot chassis" amp. But if the unit being tested is an amp with a power transformer, won't it already be sufficiently isolated (except for the primary side) as long as I use a 3-2 prong "cheater" plug on the power cord?
-
There is no danger when testing that has it's chassis bonded to earth with a green wire in a 3 prong power cord. Don't use a 3-2 prong cheater.