HSE Schmidt Elektronik
Tube Radios, Record Players,
Tape Recorders, Tefifon, Television Sets
Electrical safety for old electrical devices
Dear radio friend,
line-operated devices, cables and metal parts that are connected to the
mains must be insulated against any human contact. There are two
devices without mains separation all metal parts are connected to the
mains voltage. The cabinet, keys, rear panel and knobs form the
For these devices it is very important that they must never be
operated without cabinet, knobs, keys or rear panel. Also
protruding screws are life-threatening. Commonly capacitors build the
insulation for the antenna AND the earth connectors. The
function of these capacitors must be checked regularly (see below).
Connecting of accessory units like second speakers, record players or
CD players etc. is NOT recommended for this construction type. There
are also corresponding capacitors that form the insulation for those
accessories. Some of these device types even do not have insulation at all for the
input and output connectors; in those cases one can often find the
notice on the rear panel: "nur für Geräte nach VDE" (only for
accessories according to VDE). Therefore loudspeakers, record players
etc. must be fully insulated and are at mains voltage.
with main insulation have a safety transformer after the mains switch
that insulates the following circuitry and the chassis from the mains
voltage. Therefore sockets and metal parts are non-hazardous for human
contact. Thus accessory units can be connected. However it happens
often that faulty capacitors, brittle cable insulations or faulty
transformers prevent proper mains insulation.
your radio, tape recorder or any other device checked from a
technician. Every electric handicraft business should have an
appropriate testing device.
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