Electronics – Spinor Info

How not to foobar something…

Nov 302023

I made some mistakes in the past. I never made a half-a-billion dollar mistake.

Neither did Chris Lewicki, but he came awfully close.

I just read this delightful account of how Lewicki almost fried the innards of the Spirit rover, destined for Mars, during an engineering test that took place just weeks before the rover was launched.

I can only imagine the sinking feeling in his stomach he must have felt when he thought that the rover was ruined. My mistakes never came close in value, but the sensation is uncomfortably familiar.

Fortunately, in his case, the disaster never actually materialized. In simple terms, yes, he plugged a cord into the wrong outlet, but fortunately, the other end of the cord was not plugged in.

To this day, Lewicki must feel like one of the luckiest persons on the planet.

The illustration is from his blog post, but its appearance suggests that it might have been produced by DALL-E. Or maybe Midjourney or Stable Diffusion? The style looks very reminiscent of AI-produced cartoon images.

Pointless waste

Economy, Electronics, Personal, Politics No Responses »

Oct 292023

Every so often, a Google Calendar reminder that I set up ages ago reminds me to charge our old cell phones. This is to prevent their batteries from dying as a result of a deep discharge.

Old cell phones, you ask? Well, yes. When we swapped phones, we kept the old ones for a while, just in case. And then we kept them because wiping them securely seemed like too much of a hassle. And then we kept them because, well, what’s the alternative? Landfill? Yes, I know, some service providers accept old phones, might even give you credit. But what happens to those old phones? Who needs them? Who can use them, with their ailing batteries and, worst of all, the absence of software updates, including security patches?

Indeed, this end of support was the main reason why we ditched phones in the past. And it really is tragic. Never mind phones old enough to have outdated specs. I have here a few devices that have hardware specs that would be reasonable on the low end even today. The devices are perfectly functional. Yet they are worthless.

This is just… conspicuous consumption, forced upon us by a society that measures the health of the economy not by its stability or sustainability but by growth. Pointless, limitless growth.

Never mind that in the meantime, the middle class shrinks, the income and wealth gap widens, society is becoming more polarized, ultimately threatening the very foundations of our Western liberal democracies. Who cares about such nonsense when there’s a new phone out there with half a dozen camera lenses and who knows what other nonsense just to make you believe that they’re worth your money and that it’s perfectly okay to throw away a capable, quality piece of electronics that would have many more years of useful life left?

Darnit, I realize I almost sound like a grumpy old commie, when in reality what I worry about is the future of a healthy capitalist society, characterized by freedom of conscience, the rule of law, freedom of speech, and freedom of enterprise. But there’s a fine line between freedom of enterprise and the “tragedy of the commons”, and when free enterprise undermines the very foundations of liberal democracy, perhaps it is advisable to do something about it before it is too late.

By the way, I really liked these Nokias. What a pity we had to get rid of them. They still function perfectly, but without security patches, they’re not worth the risk.

Engineering challenges

Electronics, Internet No Responses »

Feb 202022

Engineers sometimes have to deal with unexpected challenges. This is especially true for systems that have to operate in a natural environment, subject to the elements, unpredictable weather, and, well, wildlife.

Take these beautiful Starlink satellite dishes. Little technological marvels that bring Internet service to rural users through Musk’s Starlink satellite constellation. Key to the system is a steerable small satellite dish that can be set up, e.g., in the backyard of the Starlink customer.

Unfortunately electronics ultimately converts electrical energy into waste heat, and the Starlink dish is no exception. The dish actually has a “snow melt” mode that is supposed to keep it free of snow and ice for uninterrupted operation. And it certainly has a comfy shape… especially when you are a feral cat in the middle of winter.

I doubt this issue was ever considered by Starlink engineers who designed the customer equipment. On the other hand, I would not be surprised if, in the future, engineering courses end up using this as an example of the unexpected, facing engineers.

Radio repairman

Electronics, Personal, Transportation 2 Responses »

Sep 122020

I have a travel radio.

It is a SONY ICF-SW1. It is an amazing little radio, probably the nicest radio ever made by anyone. It looks more like jewelry than a radio.

It is an immensely capable universal receiver, with continuous tuning in the AM band between 150 and 29995 kHz, and in the FM band between 76 and 108 MHz. About the only shortcoming that was mentioned by its critics is that it is a shame that such a radio does not offer the ability to selectively pick modulation schemes (e.g., narrowband FM, SSB).

I bought this radio maybe a quarter century ago, back in the 1990s. (So I guess it qualifies as an antique, despite the fact that there really are no comparable receivers out there that I know about.) I thought about buying one for quite some time but at first, I refrained as the radio was quite pricey. But one day, while waiting for my flight back home at Budapest Airport, I could not resist anymore: I saw the radio at the duty free shop and bought it.

Come to think of it, it must have been 1993 or earlier, because as I recall, the radio was already in my possession when I visited Beijing in the fall of ’93. As such, it began to show signs of age, its sound quality deteriorating because of aging electrolytic capacitors.

A few months ago, I purchased a capacitor kit off eBay, in the hope that I might be able to repair the radio. In fact, I began the repair job back in the summer, starting with taking the radio apart; not an easy task by itself, as it requires not just the removal of countless screws, not just carefully separating snap-together parts of the radio’s case without causing damage, but also desoldering several wires.

Back in the summer, I successfully replaced two capacitors but then I put the radio aside. It was hard work, and very easy to make irreversible mistakes working on submillimeter scale parts with a soldering iron. As I attempted to replace a third capacitor last night, I managed to rip up a small patch of the printed circuit board. I was able to repair the damage with a piece of wire, but this was the point when I said, enough is enough; “do no harm” should be my mantra, and I certainly do not wish to destroy this beautiful little device. So I decided to forego the rest, in the hope that the two largest capacitors that I replaced (the third was a backup capacitor for the microprocessor, to keep it powered while replacing batteries) would be sufficient. I did, however, replace the display backlight: the original backlight was a low-luminosity green LED, which I replaced with a modern, high-luminosity white LED that I received as part of the kit.

Putting everything back together was a challenge, too, and not just because the light didn’t work at first (bad soldering on my part). Ultimately I managed, though I ended up with four surplus screws with no place to go. (I think I know where they’re from, but they are redundant, and there’s no way I am going to take this radio apart again just to put those screws back in.) And much to my surprise, the radio works, and its sound quality indeed improved noticeably.

As I was studying the circuit diagram of the radio, I kept wondering what possessed SONY to produce a little marvel like this. This radio is insanely complex, with its multiple circuit boards in an absolutely tiny package. The number of distinct parts (each carefully labeled in the service manual with replacement order numbers) is astonishing. Was it a labor of love? Were they showing off? Probably both.

Failed TV repair

Electronics, Personal No Responses »

Feb 032019

I have been fancying myself as a TV repairman (I know, I know, a completely useless skill set in 2019) ever since I successfully repaired a 25-year old SANYO television set. I figured I would repeat that success with an even older television: my first television set in Canada, a 1986 Mitsubishi CS-1454C portable television. (By “portable”, they mean it weighs less than about 25 pounds and it can be hauled from one room to another without the use of a forklift.)

The problem seemed simple enough: The TV set refused to turn on. Obviously, I expected a faulty power supply or something similar, maybe due to an aging capacitor somewhere.

Alas, nope. The power supply was doing what it was supposed to do, supplying low voltage power to all the relevant parts, including the integrated circuit that was responsible for activating the relay that, in turn, would have turned on the set. But the relay never got the signal that would have turned it on. The transistor that controlled the relay never got the signal either.

Why? Well, the signal to that transistor comes from a microchip:

It comes from pin 28 of a chip labeled μPD-1709CT. What is this chip? Well, it turns out that it is, in fact, a 4-bit microcontroller with about 1.5 kilowords of ROM, factory programmed by the chip manufacturer (NEC) with code supplied by the customer.

I checked, and the microcontroller has everything. It has power, it has a clock signal. It scans the front panel keypad with beautiful, nice square waves on my oscilloscope. The one thing it does not do is outputting a signal on pin 28 when I press the Power button; which, in turn, would have provided a signal for the relay, which in turn would have energized the rest of the unit.

I am therefore forced to conclude that this television is not repairable. Even if I found a replacement chip, chances are that unless it is from the same unit, its program code would be incompatible. (The same family of chips has been used, e.g., in car entertainment systems.) Since I doubt that the manufacturer still provides support for a unit that was sold 32 years ago, the only possible source for a replacement chip would be another, cannibalized television set.

And, of course, the thing is just not worth the effort. An old style, analog television set with a CRT? Years older than half the human beings presently alive on Earth? Still, it was worth a try… I like fiddling with these old devices. Although I much prefer success stories, of course.

TV repairman

Electronics, Handyman, Personal No Responses »

Mar 182018

Anybody interested in hiring a competent TV repairman?

No, just kidding. Nobody makes a living from TV repair anymore. (On the other hand, if you are interested in hiring a competent IT contract professional… but I digress.)

Still, I have this compulsion, trying to repair broken things even when they have little or no practical utility. So it came to be that I felt compelled to repair this old SANYO AVM-2664U analog 26″ CRT TV, with a circuit board that was buzzing louder than a hive of angry wasps, as shown in this thermal infrared video which I made while I was hunting for possible hotspots on the circuit board:

Eventually, I managed to track down the problem: One lousy little capacitor.

As I told my wife, it would be fun, doing this for a living. Unfortunately, nobody is likely to pay hundreds, maybe even thousands of dollars to repair an old television set that not even thrift stores want anymore (too heavy, too obsolete). Yet another perfectly useless skill in the year 2018.

TV repair

Canada, Electronics, Handyman, Personal No Responses »

Nov 262017

Yesterday, I went grocery shopping.

I came home with groceries and a TV.

You see, Loblaws was selling cheap 32″ smart TVs at the checkout counter. Only 150 dollars (Canadian), and they even paid the sales tax.

We were in need of a TV. The TV that we have in the bedroom (rarely used, but good to have; it’d have been nice earlier this month, when I spent a few extra hours in bed on account of feeling miserably sick) is old, useless and broken. Useless because it’s an analog TV, and there is no analog service anymore, nor do we have an extra settop box for upstairs. And broken because… well, even when it was still actively in use, we needed to whack it every so often, as after it warmed up a little, its picture became elongated and discolored… but a good, well-aimed whack fixed it. Lately though, the picture was permanently distorted and in addition, the TV made a horrible, rattling, buzzing sound (and no, it didn’t come from its speakers.)

Anyhow, we now have a new TV in the bedroom. It picks up OTA digital channels just fine using a small antenna, and it works well with Netflix and YouTube. Perfect. And I managed to haul the old TV downstairs this morning. (It’s incredible just how heavy these larger old CRT televisions are.)

Before throwing it out, I decided to open it up. Who knows, maybe I can fix it and in that case, it can still have a second life at the Salvation Army or whatever. The later it becomes landfill, the better for all of us. So I decided to check this old beast’s innards. Which, in case anyone is wondering, looks like this (yes, I took several pictures just in case I disconnect something that needs to be reconnected the right way):

After removing the back cover and then vacuuming out a few pounds of accumulated dust, I powered it on, listening for the buzz. I also looked at the circuit board using my IR camera. My attention was quickly drawn to the left side, where there are some rather hot parts, but that turned out to be a bit of a red herring: the hottest part is a high-wattage resistor that is meant to shed a lot of heat. Next to it though… what I thought was an inductor turned out to be a relay. And that’s what appears to be rattling!

I checked online. Surprisingly, this is a standard part, not model-specific, still being sold. But the first price I saw was something like $12.50 US plus shipping. Way too much to invest into a 23 year old CRT television set. But then… I found an offer from China for the princely sum of 75 US cents, plus 35 cents shipping. $1.10 in total. Of course I ordered it.

So now I wait. When the part arrives, I’ll attempt surgery. If it fixes the TV, we’ll find a good home for it. If not… landfill, landfill, here we come.

Incidentally, this television set was assembled in Canada. How about that. I don’t think there are many television sets assembled in Canada these days.

More hardware hacking

Computers, Electronics, Personal, Television No Responses »

Oct 142015

I finished this weeks ago but never had the time to post. My previous attempt to hack a Rogers cable decoder was only partially successful, so I gave it another try, with better results.

By “hack”, I don’t mean illegally obtaining cable signals or anything like. I was simply looking for a way to get composite video and stereo audio out of the “free” cable boxes that Rogers provides, as opposed to just a plain RF signal on channel 3. The reason is pretty mundane: I’ve been using a dual-tuner TV card in my computer for years, which allowed me to record one program while watching another. The transition by Rogers to full digital cable messed this up: the TV card has only one RF input, so it is impossible to attach two decoders that could supply two signals simultaneously. But the TV card does have two independent composite video inputs. So if only the decoders had the corresponding output…

Well, they do, sort of: the only problem was that the audio was an undecoded (multiplexed) stereo signal. To decode it, I first built a standard stereo decoder circuit, but that was before I learned that the NTSC standard for stereo also includes noise suppression.

Hence my second attempt, using an appropriate chip.

Once again, I used a custom printed circuit board of my own design, and once again, it worked like a charm. The only fly in the ointment is that this larger board no longer fits inside the original decoder casing without some “plastic surgery”; so chances are that if it ever comes to returning these boxes to Rogers, I’ll be paying for them instead. Oh well.

Fluorescent nonsense

Commerce, Electronics No Responses »

Aug 062015

Here are nearly all the parts from a recently failed fluorescent bulb, which I disassembled:

Most of these parts are perfectly good, mostly generic electronic components that often end up in the trash. All because of these:

Yes, a rotting electrolytic capacitor. The Great Capacitor Plague is supposedly a thing of the past, but bad capacitors still show up quite often. One cannot help but wonder about the possibility that this is not altogether accidental… after all, more frequent replacement of these supposedly long-lasting bulbs means more profit to manufacturers.

Hardware hacking

Computers, Electronics, Personal, Television 1 Response »

Feb 172015

Today, I successfully hacked one of my Rogers cable decoder boxes. No, not to do anything illegal, just to get composite video and demultiplexed stereo audio out of them, to make them more usable with the dual-tuner TV card that is in my desktop workstation.

This is the first time ever that I used the services of a custom printed circuit board manufacturer. My design worked on the first try. I am mighty proud of myself.