German tube radios from the fifties and early sixties met all requirements
concerning electrical safety when they were put on the market. But they
don't meet the necessary safety standards of today.
Please note, that after 40 years, there is no product liability by
Turning on and operating old radios is done at an individual`s own
Forty to fifty years ago, people were knowledgeable about the risks
when operating these radios. The most important instruction was printed
on the rear panel:
"Vor Abnehmen der Rueckwand Netzstecker ziehen", which means:
Do not remove the rear panel before un-plugging from the power supply
Some of the rear panels can be removed without using any tools. Some
parts behind the rear panel (like the fuse) are connected with the main
household power line, others are on high DC voltage (up to 300 Volts).
Some radios are made to operate on both AC and DC ("Allstrom").
When working with an AC/DC set, extreme caution can`t be stressed enough.
This type of radio mostly can be detected by the usage of U-series tubes,
like UCHxx, UFxx, ULxx, ...
Make sure that your radio is out of the reach of children.
Pay attention to the distance between the rear panel and the wall. Make
sure that air can circulate through the rear panel.
Check the fuse (fuses) for correct value and type (i.e. "slow blow").
There is no power supply (mains) transformer, and the chassis is connected
to the power line. All the screws connected to the chassis have to be isolated,
even the mounting screws of the knobs. Don't operate this type of radio
next to a grounded device like kitchen equipment, water pipes, or a place
you are not sure that could be grounded.
But there are some additional risks due to the age of some components,
like open or shorted capacitors.
Always plug the power line into a switchable socket.
Never operate the radio when you can't see or hear it.
Unplug the mains plug or turn off the socket switch if you will be gone
for a few days or more.
Make sure that there is no voltage at the chassis due to damage of some
specific capacitors in the power supply unit.