Radio Servicing Information
For use by legally qualified and licensed repairers only
Countries have laws regulating who is legally allowed to repair or work on electrical equipment that will be plugged into the mains electricity supply. This is to protect the public from the risk of electric shock. If you are not lawfully allowed to repair electrical equipment yourself, you must find an electrician, a licensed electrical mechanic or electrical contractor or electronic technician to do any work on the equipment.
Different countries use electricity supply at different voltages. The United States uses 110-120 volts AC. The United Kingdom and Australia (amongst many other countries) uses 240 volts AC. Any electric shock at Voltage 110v or above is likely to be lethal.
Many types of early consumer electronic equipment were constructed at a time of excitement over the new technology of wireless broadcasting. A lot of radio sets were built at that time by home hobby constructors. The importance of electrical safety was not given the priority it is today, and many early radio sets etc have mains electricity wiring and metal mains voltage terminals fully exposed to be touched once the metal chassis is removed from the wooden case or bakelite housing. This would never be permitted if that equipment was manufactured under the electrical standards of today. Current manufacturing is controlled by international safety standards to protect consumers from the risk of electric shock
Another issue is that the insulating materials in use in the early days of radio were more of the organic (read biodegradable) type which can have perished or become brittle or just fallen off after many years of age and hot working conditions.
Some early and later television sets also had parts of the internal metal chassis inside the insulating plastic case connected directly to the mains voltage (Live Chassis!) Beware.
This is why any electrical work to restore or repair an old radio must be done by a licensed electrical technician.
A complete safety check of the mains wiring and insulation and all the components connected to the mains wiring should be done by an licensed electronic technician before it is safe to connect an old radio or other equipment to the mains power. YOU MUST NOT ATTEMPT TO REPAIR THE RADIO YOURSELF UNLESS YOU ARE LEGALLY ALLOWED TO DO SO.