Got my 150B back from rehab. The local tech did a thorough job and I had him install a proper grounded 3 prong power cord. Yes he did remove the death cap as well. I plugged in the power cord and instantly there was hum thru the other amps that were on. Although the 150B was not switched on yet. Then my guitarist suggested I use another outlet i.e. a different circuit for power. Which i did via an ext cord. Hum goes away. Amp still off, I pick up the bass input cord to the 150b and a splitter box which was plugged into a mixer channel and... WHAMMO a big 120v across my body . I was awake now ! Fortunately I have a good heart and have withstood being zapped before, once or twice. So we miked the bass cab instead of splitting the bass output. Little did I know that the whole time playing was a accident waiting to happen again. We got thru rehearsal and I talked to my tech to make sure of what he had done and he was all good. He explained to ck all power outlets and do voltage check across the two different path'ed input cables to make sure. So today i bought a ground/phase tester for 5 bucks, to troubleshoot all outlets (they are wired properly) and the hum etc Did the ck with VOM to make sure there was no voltage leaking to the grounds of the input cables and with the amp into the same circuit power outlet without using the ext cord - hint . Then I ck'ed the ext cord and VIOLA there it was, the ground was lifted, cut or disconnected in the cord. Using another cord and also with amp right into the wall outlet I ck'ed everything again : no voltage, Good. One problem solved, the critical one ! Now with the 150b turned off but plugged into the same power circuit as the rest of the gear, which is on, there is that good 60hz hum from the other amps. btw: nothing is plugged into the 150b inputs at this point. What is my solution here ?