Greetings from Vancouver Island Canada, regarding conversion to A.C voltage in Nottinum in the late 50's. To work on D.C. 200v the t.v.'s of the day, monochrome (dark and light) 9" to 14" televisions had to have power supply selectors to choose DC or AC via little plugs and sockets. When AC was selected the rectifier and smoothing capacitors were bought into use. They were already in circuit but the filter caps were often 'leaky' and showed up as a load of 50 cycle hum in the sound and vision and had to be replaced. Working on a damp stone kitchen floor (good earth potential) in the kitchen where a lot of t.v.'s were viewed and a 'live chassis' operating on DC 200v mains meant that the first thing you did after taking the cardboard back off the set was to stand on it for 'insulation' from the floor. Regarding cost of labour etc for engineers time, remember these were the days when a high percentage of viewers rented their televisions because of the high call out rate for repairs. I often wonder how many t.v. technicians were electrocuted during that time period altho' I did not hear of any locally. Many of the old Victorian terraced houses were extremely damp and this caused a lot of arcing in the EHT (extra High Tension) several thousand volts, areas of the set, and the dag graphite coating on the back of the cathode ray tube used to peel off and cause a strong smell of ozone in the home. I remember the customer would open the front door to let you in and you could smell the reason for your visit before you stepped into the home!
As I go grocery shopping at the megastores and see people buy a t.v with their shopping to hang on the wall I smile and think what a lot of changes I have seen over the years. Believe it or not, I actually used to look forward to going to work, I enjoyed it so much.