The tester - a device for measuring voltage and current, resistance and other electrical parameters - is an indispensable assistant in the repair of electrical wiring, various household electrical devices, electronic equipment.
When purchasing a tester, choose a model with arrow indication. Digital scale testers are less convenient in practice. Do not buy very compact models, slightly larger than a matchbox. All the inscriptions on the indicator are small, which is very inconvenient.
In order to quickly find faults with the help of a tester, they need to be able to use them. One of the most common uses for the tester is for continuity testing. In the event that you need to check a short wire without any load sources included in it, put the knob for switching the measurement ranges to the diode icon. Then touch the test leads of the tester to the ends of the wires of the circuit under test. If the wire is intact, the arrow of the device will deviate to the edge of the scale. With a digital tester, the reading will be close to zero resistance.
In order to check the voltage in the network, put the device to measure alternating current, the measuring range should not be lower than 300 volts. After that, feel free to insert the test leads of the device into the socket - the device will show you the voltage in the network.
To measure DC voltage, switch the instrument to the appropriate mode. Make sure that the measuring range is not lower than the intended voltage. In the event that you do not know what the voltage may be, first turn on the device on a large range, then, having estimated the voltage value, set a smaller range for more accurate measurement.
With the help of a tester, you can check the health of many components of electronic equipment. For example, a diode must only pass current in one direction. The resistance of the resistors must correspond to their value. The base-collector and base-emitter transitions of transistors must be open in one direction and closed in the other, the collector-emitter transition must be closed in both directions.
Since there are different types of transistors, have the appropriate reference handy when checking. In some cases, radio components can be checked without unsoldering them from the board. In the event that the readings of the device do not give a clear picture (other radioelements affect), the part must be evaporated. For resistors and diodes, it is enough to evaporate one leg.
When checking capacitors, it is more convenient to use a dial gauge - by just one throw of the arrow, that is, its rapid movement to the right edge of the scale and back, one can judge its serviceability.
If you need to measure the voltage on the board of a working electronic device, attach the negative wire with a "crocodile" (if included) to its "ground" - usually it is the metal frame of the device. If there is no such frame, look for ground around the edges of the board. Use a positive probe to measure the voltage at the terminals you need.