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I don't think I'm far off if I say that quite a lot of people have had electronic devices fail because of overvoltage. It happens for various reasons, but the result is almost always the same: the power supply burns out. Just as there are different causes, there are also different ways to deal with the problem, and that's what we'll talk about today.

For quite a long time, the simplest solutions were used to test, for example, a power supply under load—powerful resistors or light bulbs. But with the widespread availability of high-power semiconductor components and the emergence of equally powerful power supplies, it became possible to make the process more convenient by using an electronic load.

About 4 years ago, I wrote an article about repairing an air conditioner circuit board. Now someone got in touch with me who had exactly the same board and exactly the same fault. At first, we were talking about the ins and outs of service centers, but one thing led to another, and the conversation turned to whether I could repair the board. Well, why not? I could, so I got it and here’s my report.

Today’s article isn’t just for the sake of it—it’s about a specific topic, as they say. I’ll be discussing one mistake that, for some reason, crops up all too often. And it’s not just beginners who make it; even quite experienced engineers do. Let me say right away: I didn’t write this post to hate on anyone, but rather for the sake of safety. And believe me, I have my reasons.

As it happens, radio amateurs most often use three basic instruments: a voltmeter, an ammeter, and an ohmmeter. But sometimes a job calls for a more complex and less common instrument: an LCR meter. Of course, these instruments come in both professional and "hobbyist" versions, but first, let's look at what an LCR meter actually is.

Today I have a short review on a very popular topic: fuses. Yes, we’re talking about the component that, as everyone knows, is the last thing to blow. Of course, there are plenty of nuances here, and I’ll try to explain some of them.

Another power supply has come my way, this time from an SVEN SB-550 active speaker system. The repair is fairly routine, but still interesting in its own way, and involves replacing the PWM controller with a non-original part.

This review—or article, whichever you prefer—is a continuation of my write-up on modifying a power supply to turn it into a low-voltage UPS. Last time, I covered a 150 W power supply and complained that the LRS-150 turned out not to be a very good fit for this purpose. So, let’s see how its bigger brother fares.

The other day, someone brought me a power supply to repair. Well, not exactly for repair: it had already been repaired and was working, but according to the person who brought it in, it was behaving strangely. The result was a little unexpected, and that’s what I wanted to tell you about today, since I think anyone could run into this “quirk.”

Not long ago, I posted an example of modifying a Mean Well UPS using my own board. That time, I used an older version of the board, which had some drawbacks due to the simplicity of the circuit design. Today, I’ll show you the new version of the board, which addresses the shortcomings of the previous design.

Today’s article is about repairing—or perhaps restoring—two power supplies from a mini PBX. These units are quite unusual and use some rather unconventional circuit designs, so this will be a long and fairly detailed article. I hope it will be useful for beginners and interesting for experienced repair technicians as well.

I hadn’t even thought about writing up this repair. Then I figured I’d just write a little and add a few photos. But I got carried away, and it ended up becoming an article about how power supplies behave when the voltage is too high, with a little extra theory about the circuitry of the chips.

In my previous article, I wrote that repairing power supplies is usually not cost-effective, and even gave examples of cases where it really does make sense. But I just remembered a simple power supply I worked on fairly recently that’s a good example of when a repair is worthwhile.

Some time ago, I was sent several different pieces of equipment to repair, including a couple of power supplies. The repairs themselves weren’t particularly difficult, but they covered a fairly wide range of common failures. I’d like to use them as examples to show what’s what, what’s best avoided, and what you should definitely do.

First, I should say that I know exactly how this charger works. It’s strange in its own right, but it’s probably better to look at the photos and read the short description. The real surprise comes at the end—I’m almost certain you’ve never seen anything like it.

These days, it’s not just how long you can run on a standalone power source that matters, but also how quickly you can recharge it. People often complain in the comments that their batteries—lead-acid or lithium—charge slowly, but don’t understand how to speed things up using “legitimate methods.” Today I’ll try to explain why this happens and what you can do about it.

I never thought I'd have to write a post like this, but I wanted to warn you about the problems you may run into when using Meest-express.

Among hobbyists—and professionals, for that matter—so-called bench power supplies are very popular. Most are essentially universal adjustable voltage and current sources. Some offer extra features in addition to the usual controls, such as trigger-based overload protection, mode memory, or remote control from a PC or smartphone. But in any case, they’re still adjustable power supplies.