envizonit.com & http demonstrate how one of the smaller Audio Video Component Racks is build. This on is very small most of the one they built are usually double and six feet tall. More videos of those to come.

I got a scanner, i know it got a very simple circuit board because i open it once, but it need warm up if i didn’t use it for a month, if i use it yesterday, it won’t require warm up to function as normal. So what is the component that need to replace, i suspect it would be the capacitor, if it is the case, would the big capacitor fail 1st or the small one. Any electronic repair expert kindly give me some ideas, thanks.

This is an important action when checking the circuit performance for analysis or when you repair a circuit/electronic device.

When testing circuits you often need to find the voltages at various points, for example the voltage at pin 2 of a 555 timer chip. This can seem confusing – where should you connect the second multimeter lead?

Measuring voltage at a point

• Connect the black (negative -) lead to 0V, normally the negative terminal of the battery or power supply.
• Connect the red (positive +) lead to the point you where you need to measure the voltage.
• The black lead can be left permanently connected to 0V while you use the red lead as a probe to measure voltages at various points.
• You may wish to fit a crocodile clip to the black lead of your multimeter to hold it in place while doing testing like this.

Circuit diagrams show how electronic components are connected together. Each component is represented by a symbol and a few are shown here:

Circuit diagrams and component layouts
Circuit diagrams show the connections as clearly as possible with all wires drawn neatly as straight lines. The actual layout of the components is usually quite different from the circuit diagram and this can be confusing for the beginner. The secret is to concentrate on the connections, not the actual positions of components.