Safety
Owner Safety
Written by Bryce Ringwood   

The main concerns with old radios are fire and electric shock hazards.

  • Most old radios are made of wood or bakelite - materials which can easily smoulder and catch fire.  Regardless of who has repaired/restored your radio, please bear this in mind. Never leave these old sets unattended. There are a number of components which can overheat and catch fire. If you smell burning, switch off, unplug and determine the cause - even if the set is apparently working.  The set must be repaired. You should have a CO2 extinguisher handy. Of course you must never use water to put out an electrical fire.
  • Safety standards of many old radio sets leave a lot to be desired. Many radios were built using an AC/DC principle, which made the chassis and knob spindles live to mains. These sets must be operated with a mains isolation transformer for safety, and the chassis should be earthed to ground. Please don't get grandad's old radio down from the attic and plug it in and switch it on - you or a member of your family may receive a nasty shock.

It doesn't do any harm to have a qualified electrician check your wiring from time to time.

Let's face it - battery operated transistor radios had a lot going for them in the safety department!

 
Lightning and other mishaps
Written by Bryce Ringwood   

About a year or so ago, I was presented with a Philips transistor radio that according to the owner had been struck by lightning. Fortunately, Old Lightning Arrester Advertthe lightning strike must have been quite some distance away, otherwise it would have been unrepairable. As luck would have it, I had replacement transistors to hand, and the worst damage was confined to the circuits in the “front end”. What was remarkable, was the fact that some of the tracks on the printed circuit board had been burned clear away, leaving a ghostly impression on the printed circuit substrate. These tracks were replaced with fine wire and a few dabs of superglue to hold everything in place and the set duly came back to life.

Aerials, by their nature attract lightning strikes. The most prevalent form of protection seems to be a “spark-gap” - simply two points of wire spaced a small distance apart so that any high voltage will jump the gap and not damage the equipment. Probably almost equally useless is my own favourite, the “gas arrestor” connected across the aerial and earth. Whilst they may be marginally effective with valve radios, they are probably totally ineffective for solid-state (i.e. transistor) circuits.

It has been a family tradition to disconnect the aerial from TVs, radios etc. While there are storms about and before going away on holiday. Last Summer, I was using a Kenwood R1000 and there was a distant rumbling. The next moment a 25 cm spark jumped from the case of the set to my finger. Amazingly both finger and radio were unscathed, but it did bring to mind how careful one has to be.

I was less lucky when ESKOM decided that if 230 volts was good, then 320 volts would be even better. This took out a printer transformer and a transformer for one of my radios (fortunately switched off!). I reported the problem to no avail and wrote the transformers off to experience.. At least, this sort of problem can be averted by purchasing a constant voltage transformer.

Call me paranoid, but unless I'm present, I unplug all my radios and disconnect them from the mains.



 
Workshop Safety
Written by Bryce Ringwood   

Here are a few tips to help you survive , if you are experimenting with valves and high voltages

  • Be sure your house wiring complies with current electrical standards and that your earth-leakage switch operates correctly

  • Never work with the equipment you are working on connected directly to the mains. Always use an isolation transformer

  • Have a mobile phone handy – if you need help you can call for it quickly

  • Use lifting equipment for large and heavy radios, inverters etc

  • Don't perch things on the edge of the bench where they may fall and injure you

  • If possible, work with one hand in your pocket – this may avoid an electric current crossing your chest

  • Work in a well-lit environment

  • When applying power for the first time, stand away from the equipment – out of the line of fire of any exploding electrolytic capacitors.

  • Wear safety glasses

  • Work in a dry environment

  • Beware of Gas. Work in a well ventilated area

  • Be aware that lead is poisonous – always wash your hands after working on repairs.

  • Read the safety instructions that come with your tools, solvents, solders etc.

  • Concentrate. If you are interrupted, stop what you are doing, and return when the interruption has gone

  • Study the circuit. Know where the high voltages are

  • Finally, my favourite, don't put chemicals in cups, glasses or other kitchenware. (Printed circuit etching fluid tastes horrible-believe me.)

  • A reader, Paul Kalil, has pointed out that there are many hazards from substances, for example, the dust in old radios could contain the hantavirus (something really cheerful to google), chemicals (PCBs) used in the manufacture etc. Among the worst is beryllium oxide used in RF power transistors. A fraction of a microgram is poisonous - never break these things open.

  • You might want to use lead-free solder on new projects. (Confession - I don't like it.) 

 

If I have forgotten something here – please let me know

 

 


Joomla template by a4joomla