TV Electrical Interlock

Recently I read Design of Everyday Things, by Donald Norman, which had a reference to the electrical interlocks on TVs. Got me thinking. These are no longer made. Even for CRT based TVs, end user repairs are long forgotten. As child I recall pulling the back off the TV and removing the vacuum tubes with my dad. These were carted over to a local hardware store, plugged into a test set about the size of a pinball machine. Various settings were made and tube functioning could be tested. Replacements were available for bad tubes. The interlock prevented powering up the TV with the back off. This prevented an electric shock risk from the high voltages in some of the internal electronics. Today most TVs are flat screen, with no tubes and no customer replaceable parts.

I found myself agreeing with Norman’s message about human factors considerations in design. When I was at Bell Labs, working on forward looking technologies, we had a human factors team as part of the Lab. The team included experimental psychologists. Their purpose was to interact with the technology developer/inventors to help identify problems and solutions with user interfaces for the new communication services that we were coming up with. This sort of design approach is used extensively now in industries like nuclear power and aviation, where safety and minimization of human errors are critical. Interestingly, according to one of our MMCi professors, Constance Johnson, this approach is only now getting consideration for Electronic Medical Record and decision support software.