Isolation transformer

[Axtman]

Do you guys use an isolation transformer?

I cannot remember a time where I used one. I don't work on series string tube gear (widow makers). If an amp comes to me with a two prong power cord, the first thing I do is install a grounded 3 prong power cord.

[xtian]

Only for "widow-maker" amps, where one leg of 120vAC wall service is tied directly to chassis, or heater string is based on 120vAC. Then, iso transformer is mandatory, because you can't make it safe any other way.

[The Dude]

I think the OP is talking about an isolation transformer as bench gear and not as installed in a widow maker. I could be wrong and maybe some clarification is necessary. I always use an isolation transformer on my bench. Every repair gets plugged into it. And yes, you need to install and isolation transformer into a widow maker amp to make it safe.

[Axtman]

I was once at Guitar Center (Yeah I know. That was my first mistake.) Iwas bending over leaning my left hand on an old Magnavox amp so that I would not fall over I then touched a crappy Fender solid state amp. I was tipping it back to see what speaker was in it when BANG! I jumped back and yelled an obscenity. I stood there wondering how I could have gotten a shock from a modern grounded amplifier. Then I looked over and saw the amp I was leaning on had two prong cord. So the chasis was hot and the electricity when up my left arm, ACROSS MY HEART, and down my right arm to the grounded chasis. A sales guy hearing my scream came over and said, "Everything alright over here, buddy?" I explained what happened and insisted that he get the Magnavox amp serviced. He took it to the back room and I left....still shaking.

[Axtman]

Yes as bench gear. I have one floating around here somewhere.

[Mick Bailey]

I use one for working on SMPS circuits. Also, my 240v to 120v transformer for working on US gear is isolated, though that just happens to be how it worked out as it's the toroidal mains transformer out of a large PA power amp.