 Either type of AC/DC radio can present the "hot" line of the line voltage on the chassis of the radio ("hot chassis") or isolated from the chassis by a single capacitor ("warm chassis").This presents a safety problem, as depending on the direction of the non-polarized plug, the hot side of the line voltage can be connected directly to all the metal parts of the radio any time it is plugged in, regardless of whether it is powered on or not.Proper repair or refurbishment requires an isolation transformer to remove the live connection, and care should be taken to never touch any metal part of the radio (chassis mounting screws, bare control shafts, etc.)