Teardown

436 Articles

Royal Typewriter Gets A Second (or Third) Life

April 8, 2024 by 13 Comments

Usually when we are restoring something with a keyboard, it is some kind of old computer or terminal. But [Make it Kozi] wanted an old-fashioned typewriter. The problem is, as he notes, they are nostalgically popular these days, so picking up a working model can be pricey. The answer? Buy a junker and restore it. You can watch the whole process in the video below, too, but nearly the only sound you’ll hear is the clacking of the keys. He doesn’t say a word until around the 14-minute mark. Just warning you if you have it playing in the background!

Of course, even if you can find a $10 typewriter, it probably won’t be the same kind, nor will it have the same problems. However, it is a good bet that any old mechanical typewriter will need many of the same steps.

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1950s Switching Power Supply Does It Mechanically

April 8, 2024 by 25 Comments

When you hear about a switching power supply, you think of a system that uses an inductor and a switch to redistribute energy from the input to the output. But the original switching power supply was the vibrator supply, which was common in automotive applications back in the middle part of the last century. [Mr. Carlson] has a 1950s-era example of one of these, and he invites us to watch him repair it in the video below.

Most of the vibrator supplies we’ve seen have been built into car radios, but this one is in a box by itself. The theory is simple. A DC voltage enters the vibrator, which is essentially a relay that has a normally-closed contact in series with its coil. When current flows, the relay operates, breaking the contact. With no magnetic field, the springy contact returns to its original position, allowing the whole cycle to repeat.

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Inside A Hisense TV Repair Attempt

April 6, 2024 by 17 Comments

Many of us misspent our youth fixing televisions. But fixing a 1970s TV is a lot different than today — the parts were big and tubes were made to be replaced. Have you torn into a big flat screen lately? It is a different world, as [The Fixologist] shows us in the video below.

The TV in question was rescued from a neighbor who was about to throw it away. If you are like us, you’ll watch the first few minutes and see it powers up, but the screen is very dark. Back light problem, right? No problem. But it turned out to be more than we thought.

Honestly, we assumed it might be the power supply, and we would have put a power supply on the LED leads to test that first. That would have been smart because taking the panel off to reveal the LEDs was very difficult! There were two bad LEDs, though, so in the end you’d have had to do it anyway.

We were disappointed that after fixing the LED, he cracked the LCD panel during the reinstallation. So, in the end, this was more of a teardown video and not a repair video. He seemed to think a lot of the tape in the unit was to thwart repairs. That could be, but we wondered if it made manufacturing the TV easier which, after all, is mostly what they care about.

This isn’t the first time we’ve heard people tearing into a TV and wondering if the factory was against them. We’ve considered it, but we are pretty sure it isn’t the case.

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Tiny Signal Generator Revealed

March 23, 2024 by 5 Comments

There was a time when test equipment was big and heavy. Those days are gone, and [Kiss Analog] shows us the inside of a Uni-T UTG962E arbitrary waveform generator. The device is truly tiny. You might think this is due to the dense packing of the circuit board. However, one board is packed but the other board seems to have a high degree of integration on one IC. You can check out the video below.

The main processor is some sort of ARM — we think an STM32F-series part. The markings were hard to make out under the microscope.

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Folding Solar Panel Is Underpowered

March 15, 2024 by 30 Comments

If you hang out on certain kinds of sites, you can find huge-capacity USB drives and high-power yet tiny solar panels, all at shockingly low prices. Of course, the USB drives just think they are huge, and the solar panels don’t deliver the kind of power they claim. That seems to be the case with [Big Clive’s] latest folding solar panel purchase. The nice thing about the Internet is you can satisfy your urge to tear things open to see what’s inside of them vicariously instead of having to buy a lot of junk yourself. Thanks [Clive]!

The picture on the website didn’t match the actual product, which was the first sign, of course. The panel’s output in full sun was around 2.5 watts instead of the claimed 10 watts. He’s also seen sellers claim they are between 20 and 80-watt panels. But the interesting bits are when [Clive] decides to rip the panel into pieces and analyze the controller board.

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A 1960s PLC Gives Up Its Secrets

February 15, 2024 by 7 Comments

When it comes to process automation, the go-to part in most industrial settings is a Programmable Logic Controller, or PLC. These specialized computers will have a modern microcontroller running the show, but surprisingly the way they are programmed still has echoes of a time before electronic PLCs when such control would have been electromechanical.

[Thomas Scherrer] has an interesting design to tear down, it’s a Siemens electromechanical motor controller from the early 1960s. It’s not quite the huge banks of relays which would have made a fully-blown PLC back in those times, but it’s a half-way house with some simple programming capability in the form of several channels of adjustable time delay.

We’re partly sad to see this unit being subjected to a destructive teardown, but nevertheless it’s interesting to see all those very period components. The current sensor has a mechanism similar to a moving coil meter, and the four-channel timer is a mechanical sequencer with four adjustable cam-driven switches. We’re not sure we would be cracking open selenium rectifiers with such nonchalance though.

These units were built to a very high quality indeed, and though it’s obvious this one comes from a decommissioned installation it’s not beyond possibility to think there might be some of them still doing their job over six decades after manufacture. Have any of you seen one of these or something like it in operation recently? Let us know in the comments. Meanwhile the video is below the break.

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In Praise Of Old Meters

January 12, 2024 by 54 Comments

We are spoiled with multimeters today. Even the cheapest meter you will get these days is almost surely digital with a tremendous input impedance. But a few decades ago, meters were almost always analog affairs. To make a precise measurement, you needed a mirror under the meter to ensure you read the needle correctly. Moreover, a common meter wouldn’t have that high of an input impedance. If you spent more, you could get a VTVM and, later, one that used FETs to provide high input impedance. [Peter AA2VG] just picked up a vintage Micronta FET volt-ohm meter to join some of the other new and old meters in his shack. You can check it out in the video below.

[Peter] already has a Simpson and a more modern Fluke meter. The Simpson, however, doesn’t have a tube or FET amplifier. The Fluke is nice, but there is something about the needle on an analog meter. If you aren’t old enough to remember, the Micronta brand was a Radio Shack label.

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