Have you ever had the experience of jumping up and laughing loudly when you finally figured out the cause of a technical problem with a PCB?  

In an era of uncertainty, a senior executive of a company once participated in a job interview, and one of his interview questions was: "How would you diagnose a problem with a printed circuit board

As you can see, this is a very open-ended question, so I immediately answered, 'I will guess first.' Then the examiner unsurprisingly asked me to continue explaining, and of course, I was also happy to continue. I explained that there are different methods to solve problems like circuit board faults (assuming you don't have a circuit board tester with a specific testing program at hand). In fact, the first thing I would do is to quickly visually inspect the circuit board, looking for obvious clues such as loose jumper wires (omissions), burnt marks around resistors, capacitor explosions, residual stress solder joints, and so on.

circuit board

This may sound a bit foolish, but over and over again, you will be lucky enough to discover some obvious clues. After the first visual inspection, one option is to carefully examine all possible faulty mechanisms, inspect components, test wiring, and observe each signal until the fault point is isolated. But the problem with this strategy is that the process is boring and time-consuming.

Another alternative, which I personally recommend, is to observe how system failures manifest in the external world, and then start random guessing based on your observations using WAG (wild ass guess).

The reason why this method is not as foolish as it sounds is that you are using your rich experience to quickly move towards areas where problems may arise; If you are right and identify the problem correctly, you can save yourself a lot of time and energy; If you guess wrong, you won't waste too much time or energy, and at least one possible problem has been ruled out.

However, at some stage, it may be necessary to examine more WAG results, and then you may return to a careful, slow, and steady progress, energy consuming analysis mode.

What? Then? Of course, I passed the interview... What silly questions are you asking!

However, none of the above are actually the focus; I think of those because I just read a series of interesting "On Call" articles on The Register, a UK technology news and commentary website. The slogan of this series is "Bite those hands that feed IT". It is a regular column every Friday where IT technology readers share the strange tasks they have performed at strange times and places.

I have read two very interesting stories so far. The first one is about a computer that restarts itself as soon as the owner flushes the toilet; The second one is that the network of a certain theater hangs up every time the audience arrives and prepares to collect tickets to enter.

That type of technical problem often makes engineers stay up late to solve, but if the reason is found, it can really make people jump up and cheer, shout and laugh... Have you ever had such an experience as an engineer? Welcome to share with us!