Workshop Safety

[ Saftey | Basics | Transformers | Speakers | Coils IF & RF | Caps | Resistors & Pots | Valves ]

If its got valves, its got hundreds of volts. Which kill. Add to that the sometimes dubious electrical safety of some vintage equipment, made worse still by deterioration over time, and the danger should be all too clear. If you're not sure, don't touch it ! And never be tempted to simply switch long dormant equipment on ... if you're lucky you'll only damage possibly irreplaceable parts. But typically it'll go bang. And if you're unlucky .... !

IMPORTANT When dealing with mains-connected equipment safety is of paramount importance. Check and double check connections and then operate with one hand in your pocket. If at all possible use an isolating transformer. First check the condition of the mains lead and plug. If any cracking of insulation, bare spots or general deterioration is evident, renew them. American sets often used mains cords with only cotton insulation. These should be replaced. Inspect the mains plug for wrong connections. If the earth lead is connected wrongly the chassis could become lethal. With your test meter set to the highest resistance range, check for any leakage between the live leads and the chassis. If there is then look for faulty bypass capacitors between the mains leads and chassis. These were common on American receivers. There could be a faulty on/off switch causing leakage, or, if storage has been in a damp situation, there could be moisture in the transformer. If moisture is suspected direct a blower heater on to the transformer for a few hours to dry it out. P.L

There are a few basic safety rules that will protect you and your new acquisition:

1. Fit your working area with a single Isolation switch, and make sure all your family know where it is, what it does and how to use it! If they can't disconnect you from the power, they can't give you any other help.

2. Use an Earth Leakage Circuit Breaker (ELCB) or a Residual Current Device ( RCD) in the supply to your workshop. These devices will not prevent you from getting a shock, but they may well prevent it from killing you. IF YOU DONT YOUR A BLOODY IDIOT

3.Use an Isolation transformer between the set you are working on and the mains supply - this can also help to protect your test equipment.

4. Keep one hand in your pocket! A simple rule, but it prevents a path across your chest and through your heart. Also make a skull & crossbones sign and put it in a prominent place when gear is open and live.

5. Never apply power to an unknown piece of equipment without a first giving it a thorough visual inspection. Look for frayed or missing insulation, missing parts, signs of damp, obviously incorrect parts, or any other signs that it may have been tampered with.

7. When applying power, do it gradually, using either a Variac (variable voltage transformer), or a series lamp. Some even recommend disconnecting the sets own power supply, and using an external variable supply to power up the equipment whilst fault finding (I must admit that a large number of faults involve the power supply, and mains transformers are very difficult to replace or repair!).

8. When working on equipment, remember health and safety wasn't always well considered, so beware of live chassis, finger sized holes in covers and other traps for the unwary.

9.A lot of materials used in older equipment are now considered to be hazardous to health, for example, Cadmium in plated parts, Beryllium in ceramics of power valves and transistors, Arsenic in thermal pastes, Mercury in older power rectifier valves (tubes), all sorts of lethal organic chemicals in capacitors (condensers), not to mention Asbestos in resistive line cord and insulation around dropper resistors. It is wise to learn about these materials, and take the relevant precautions when handling them!

10. A final simple rule, keep small children and pets out of the working area, what you do to yourself is up to you, but injury to others is unforgivable!

<edited, original author unknown>

Workshop Safety Tips