IMPORTANT SAFETY NOTES

Switch mode power supplies are LETHAL. If the circuit of a typical supply is studied, it will be seen that a good part of it is either at mains potential, or even worse, is at mains potential with a large DC voltage (typically around 340V) floating on top.

ONE MISTAKE CAN KILL YOU. DO NOT WORK ON A SWITCH MODE POWER SUPPLY UNLESS YOU ARE ENTIRELY COMPETENT TO DO SO. IF YOU DON'T FEEL CONFIDENT, GET SOMEBODY QUALIFIED TO DO THE WORK FOR YOU.

Never open a switch mode supply when it is connected to power, even if it is turned off. Never operate a supply with the cover off. Never assume that the main filter capacitors which store the 340VDC are discharged. Check these with a multimeter and if necessary discharge them with a 240V 40W light globe which has been fitted with well insulated test probes. Never short these capacitors with a screwdriver blade or similar- you may damage them internally and also damage the PCB and yourself.

In short, adopt safe working practices and you will still be around to enjoy using the results of your efforts.

Click here to certify that you have read and understood these safety precautions, and to proceed to the next section