Forgotten Voice

This story involved a large (in those days - 1980) account near Birmingham, with twin System/3 Model 15 Systems.

There was some scheduled maintenance due on one of the Systems, and for whatever reason, I was unable to be there to do the job. So another CE was sent.

I can't remember the exact part being replaced, but certainly something to do with one of the power supplies. Anyway, the CE in question first powered down the system. And then, of course, opened the side panel of the system unit to trip the circuit breaker in order to ensure that there was no power to the parts he was about to replace.

Now that he thought it was safe to do so, the CE took a screwdriver, and started to remove the part to be replaced. Soon after that, there was a loud bang, and a flash of light, clearly visible in the room next to the computer room, where the DP Manager and programming staff looked on. Fortunately, the CE wasn't injured (except for possibly his pride and reputation).

What had happened? The CE had quite correctly turned off the 3-phase supply to the system unit. Trouble was, he was replacing a part in the attached 5421 Printer Control Unit, which also had its own separate 3-phase supply which was still live!

And thereafter, the Customer always referred to this particular CE as 'Sparky'.