How to avoid short circuit by measuring the voltage of each line on the circuit board with a multimeter
When measuring any circuit electronic components with a multimeter, you must first check the status of the multimeter before your test leads touch the electronic circuit components. For example, if you measure DC voltage, you must switch to the gear of DC voltage. How big, the first is to hit the gear to the highest gear. If you are measuring AC voltage, you must switch to the relevant gear for AC. If you don’t know the voltage, you must first switch to the highest gear to measure. After turning to the highest gear and measuring the data, adjust the gear as needed for accurate measurement. Reminding everyone to check the status of the multimeter is to prevent some people from directly measuring the voltage when the multimeter is in the resistance or capacitance range, which will cause the possibility of short circuit and burning things. Therefore, before measuring anything, you must develop a number habit, that is, you must check the gear status of the multimeter, and then measure after confirming that it is correct.
First of all, let's answer the main question of the following topic: how to avoid short circuit by measuring the voltage of each line on the circuit board with a multimeter
1. A multimeter tip as sharp as possible
When I was studying and still in school, I followed a habit of my brother, that is, I like that the metal front ends of all my multimeters are polished very sharply. The sharp multimeter tip can touch the circuit board as small as possible. For the measurement of some small-area patch components, it can prevent the pen tip from being too thick to accidentally touch adjacent contacts.
2. Find extra black pens and transform them into crocodile clips
Find a pair of extra test leads, cut the black test lead, the end of the hand pen, and find an alligator clip to solder it on for spare. Of course, if you don't want to do it yourself, you can buy ready-made ones, including red and black pens.
To measure the voltage of the circuit board, first determine whether the part of the circuit board to be measured is DC voltage or AC voltage. If it is DC voltage, first set the gear of the multimeter to the gear of DC voltage measurement, and then take a black pen in one hand and the other hand Take the red pen, and the black pen is the grounding terminal. Try to find the grounding point that is easy to put and touch as close as possible. Generally, the grounding point is a relatively large circuit board. The red pen is then separated to measure the circuit to be measured. At this time, the sharper the tip of the multimeter is, the more convenient it is to measure some fine chip component circuits. If the two hands are inconvenient to hold the test leads separately, as we said earlier, the spare test leads with crocodile clips can come in handy at this time, connect the black test leads with crocodile clips, and clip the crocodile clips to the circuit board. On the ground point, the red test lead can measure the entire DC circuit at will.
If you encounter a particularly thin circuit and do not have a sharp enough test pen tip, you can find a sewing needle and wrap the sewing needle on the pen tip of the test pen with a thin copper wire without insulation, which can also be measured.
Some things to pay attention to when measuring AC voltage with a multimeter
When we use a multimeter to measure voltage, in many cases, the voltage of the AC mains will be measured. When measuring the AC voltage, first of all, remember to check the gear of the multimeter. Only when the gear is correct can we start to measure.
Before the power is turned on, try to use the alligator clip to clamp a point of the AC voltage circuit to be measured, then turn on the power, and then use the other hand to take the red test lead to measure various points in the circuit.
If there is no alligator clip, when you need to measure, if the AC voltage is not sure whether it is low voltage or high voltage, please pay attention to take two test leads with one hand to measure, just like using chopsticks to measure the AC mains voltage circuit.
This operation is to ensure safety as much as possible. If two hands each take a test lead to measure, in case the test lead leaks and breaks down through the two hands and gets an electric shock, the position between the two hands is the heart, which is very dangerous.
This operation is very necessary. Many people who do maintenance know that most of them have been electrified by 220V AC. I myself have been electrified. I accidentally touched the AC circuit when repairing a color TV. Fortunately, it was done with one hand. .
Regardless of measuring DC or AC circuits, if you want to prevent accidental short-circuiting as much as possible, separate the red and black test leads as far as possible, and the tip of the test lead must touch the measurement point of the circuit vertically.
