Precautions for PCB power-on

- Aug 31, 2020-

For the PCB that has just been soldered, after confirming that the schematic diagram of the board is correct and checking it carefully with a multimeter before powering on. Are you still worried about what splendid things will happen immediately after power-on? For example, sparks or even photos! Today, I will talk about the various fantasy experiences of the engineers during the first PCB power-on. It is absolutely amazing after reading it!

01 complaint


The sister paper of the laboratory, every time the board is powered on for the first time, we have to ask our guy to go...

@ Eric Luo:

As the motherboard maker, I always felt that the weak current was not dangerous at the beginning, until later there were two destructive experiments, one mos exploded in my face, one sparks from the power supply, and then every time I was powered on, I was worried. .

@I will become a giant, stepping on strength, stepping on dreams:

Have you seen the splendid scene of the explosion of 1600V 4800μF capacitors? Have you ever seen the 1000A current arc in the actual field?

02 Funny version

@Anonymous user A:

Just like having a girlfriend for the first time, you will get used to it when you have more, and you will know how to not blow up!


There must be a sense of fear. Every time before power on, I find a piece of cardboard to cover all the capacitors. Will I talk nonsense?

@Anonymous user B:

A buddy of mine, an internship project, made ten prototypes, all of them burned out, so they didn’t get a regular job, and quit...

03 Dangerous Edition


It means that the output of 200v or more was caused by turning off the coupling voltage regulator. It directly exploded a voltage-limiting 16 volt capacitor, and the explosion of the capacitor shell hit the eyes. Fortunately, the eyes closed quickly and slightly scratched the outside. Nothing else on the eyelids.

Anyway, when dealing with electricity, be mentally prepared for accidents. It is not a strong electricity, people will not be troubled, but also careful and rigorous to ensure the lowest accident rate.


I can't be regarded as an electronic engineer, but I am now engaged in electronic work. I usually draw schematics, PCB diagrams, generate gerber files, and then make PCB boards.

Once, the boss asked to test the board, can it be used? In order to save time, the boss directly puts on a strong power, more than 300 volts!

When I first turned on the power and looked at the functions, I didn’t feel any fear. The boss didn’t trust me to test by myself, so he asked a colleague to accompany the test. The colleague who accompanied the test was a graduate student. After training, you don’t want to die, it's all high-voltage electricity, you have to stay away from the fire...

Having said a lot of things that I should have paid attention to, but did not.

When I didn't know the first board tested, the thermistor exploded without warning, and the sound was loud. At that moment, I was shocked. It took 10 seconds for me to react.

When I tested it later, I would first step back one meter away, and then power on, um, yes, it left a shadow, and I was really scared.

04 Technical Edition


In fact, the pcb power on is not so terrible, as long as the following points are achieved in the early stage, the problem will not be big.

1. Check the key components, especially the polarity capacitors, for reverse insertion, false soldering, missing soldering, and continuous soldering (the components may be short-circuited and burned).

2. Try to use an adjustable power supply, adjust the voltage first, and then turn on the current slowly when powering on and debugging. When the current is much higher than the estimate, turn it off immediately and check if there is a short-circuit part, or it may be the position of the adjustable resistance. wrong.

3. The most important thing next is to add jumpers. This is great for debugging. I heard an old senior engineer said that good circuits are designed for three points and seven points for debugging, so please unplug you before powering on Jumper cap.

05 Summary Siege Lions, work is precious, life is more expensive, PCB power-on is risky, and you should do it and cherish it. Please be attentive and attentive when working!

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