Curious Marc Takes On Sewing Machine Repair

November 4, 2021 by Adam Fabio 29 Comments

Even the most talented engineers can be stymied by simple repair projects. In this case, repairing a broken sewing machine has [CuriousMarc] all tangled up. [Marc] is probably best known as a part of the team who managed to restore and boot up an apollo guidance computer, but he’s worked with plenty of other vintage machines.

This problem hit much closer to home. [Marc’s] daughter wanted to sew a Halloween costume. The machine would boot up fine, but when attempting to sew, it would make a bit of noise, then beep and display “The safety device has been activated”. Not very helpful.

The sewing machine in question is called “Baby Lock Decorator’s Choice” and is manufactured by Brother for Juken. [Marc] of course dug in, and quickly found himself stymied by a clamshell case that just didn’t want to come apart. This is the point where many of us would apply just a little too much force when prying and be rewarded with a broken case.

[CuriuosMarc] is thankfully the more patient sort. Rather than become [FuriousMarc], he carefully persevered to find a hidden screw holding things together. The screw could only be accessed by inserting a screwdriver through a tiny access hole on the front chassis of the machine.
With the screw out, a couple of molded clips were all that held the case sides together. After popping them, [Marc] was finally able to fix the real problem: A toothed belt that had slipped off its cog. That’s it — just a loose belt. The cryptic error code most likely was due to the machine realizing it the motor was on, but the machine wasn’t moving – which would generally indicate something stuck or tangled in the thread path.

This type of repair would be much easier if service manuals were readily available. We did a quick search for this model but didn’t find anything freely available.

Have you gotten stuck by a simple repair? Tell us about it down in the comments.

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There’s Not A Cassingle Thing Missing From This Cassette Deck Masterclass

October 26, 2021 by Kristina Panos 78 Comments

For [ke4mcl], this whole cassette craze of late is not a new discovery so much as it is a personal nostalgia machine. Since [ke4mcl] sees a lot of basic questions go unanswered, they made an incredible beginner’s guide to all things cassette deck. This concise wealth of information covers everything from terminology to operation, basic maintenance like repairing the belt and lubricating the motor, and appropriate cleaning methods for the various parts. Yep, we’re pretty sure this covers everything but the pencil winding technique, which you probably already knew about.

You don’t need a lot of tools and supplies to maintain a cassette deck or twelve (apparently they’re addictive) — mostly just head cleaning fluid, isopropyl, window cleaner, and a bunch of cotton swabs. And given this guide, you’ll enter the enclosure confidently, armed with knowledge about everything from the belts to the capstan to the head. This is valuable information, the kind of stuff your older brother wouldn’t take the time to explain to you in the 80s. But maybe he didn’t know reverse bias from the holes in the top of the tape.

Don’t care for the quality of audio cassettes? Tapes are good for lots of stuff, like data storage and decoration.

Valve Reluctantly Shows How To Mod The Steam Deck

October 14, 2021 by Tom Nardi 35 Comments

As the narrator in this official instructional video from Valve reminds the viewer several times, the gaming company would really rather you not open up your brand new Steam Deck and start poking around. They can’t guarantee that their software will function should you start changing the hardware, and since there’s no source for replacement parts yet anyway, there’s not much you can do in the way of repairs.

That said, Valve does believe you have the right to take apart your own device, and has produced the video below as an aid to those who are willing risk damaging their new system by opening it up. Specifically, the video goes over how to replace the most likely wear items on the handheld, namely the thumb sticks and the SSD. It seems inevitable that the stock thumb sticks will wear down after a couple years of hard use, so we’re glad to see they are easily removable modules. As for the SSD, it stands to reason that users would want to swap it out for faster and higher capacity models as they become available in the coming years.

Sooner or later, these are going to need to be replaced.

Now to be clear, we appreciate Valve making this video, and would love to see other manufacturers be so forthcoming. But we have to admit that some of its messaging does seem a bit heavy handed. The narrators admonition that users who open their Steam Deck are literally taking their lives into their own hands due to the danger of potentially rupturing the system’s lithium-ion battery is a bit hyperbolic for our tastes. The constant reminders of how badly you could bungle the job just comes off as overly preachy, though to be fair, we probably aren’t the intended audience.

Outside of its obvious gaming functions, we’re excited too see what the community can do with the Steam Deck. With official reference material like this, perhaps we’ll even start seeing some hardware modifications before too long. Though we wouldn’t blame you for hitting the Mute button halfway through.

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Decoding SMD Part Markings

October 6, 2021 by Chris Lott 28 Comments

You’ve probably encountered this before — you have a circuit board that is poorly documented, and want to know the part number of a tiny SMD chip. Retro computer enthusiast [JohnK] recently tweeted about one such database that he recently found, entitled The Ultimate SMD Marking Codes Database. This data base is only a couple of years old judging from the Wayback Machine, but seems to be fairly exhaustive and can be found referenced in quite a few electronics forums.

Unlike their larger SMD siblings, these chips in question are so small that there is no room to print the entire part number on the device. Instead, the standard practice is for manufacturers use an abbreviated code of just a few characters. These codes are only unique to each part or package, and aren’t necessarily unique across an entire product line. And just because it is standard practice does not imply the marking codes themselves follow any standard whatsoever. This seemingly hodgepodge system works just fine for the development, procurement and manufacturing phases of a product’s lifecycle. It’s during the repair, refurbishment, or just hacking for fun phases where these codes can leave you scratching your head.

Several sites like the one [JohnK] found have been around for years, and adding yet another database to your toolbox is a good thing. But none of them will ever be exhaustive. There’s a good reason for that — maintaining such a database would be a herculean task. Just finding the part marking information for a known chip can be difficult. Some manufacturers put it clearly in the data sheet, and some refer you to other documentation which may or may not be readily available. And some manufacturers ask you to contact them for this information — presumably because it is dynamic changes from time to time. Continue reading “Decoding SMD Part Markings” →

A soldering iron applied to a stuck threadlocked screw in a titanium pen

Removing Threadlocked Screws With A Soldering Iron

October 4, 2021 by Chris Wilkinson 27 Comments

We’ve all been there – that last stubborn screw, the one thing between you and some real progress on a repair or restoration. It’s stuck tight with thread-locking fluid, and using more torque threatens to strip the head. Frustration mounting, drilling that sucker out is starting to seem pretty tempting. But wait! [Daniel] offers a potential solution using nothing but a soldering iron.

This tool hack is pretty simple, but all the great ones tend to be straightforward. In the video, [Daniel] is faced with a titanium Torx screw that refuses to come loose due to threadlocker, an adhesive that is applied to screws and other fasteners to prevent them coming loose. Available in a variety of strengths, thread-locking fluid is great at keeping screws where they need to be, but too much (or the wrong kind) can seize a screw permanently.

Instead of drilling out the offending screw, [Daniel] reaches for his soldering iron. By applying a significant amount of heat to the screw head, the adhesive starts to give. After heating, working the screw back and forth breaks the threadlocker, thus freeing the screw. The whole process takes just a couple of minutes, and potentially saves the repairer from destroying a screw.

The chemistry behind thermoset adhesives makes for some great bedtime reading, however the main takeaway is that threadlock fluid, while somewhat resistant to heat, will eventually become brittle enough for the screw to come loose. Unlike most adhesives, which melt under high temperature (think glue sticks), thermoset materials tend to initially harden with the application of heat, before turning brittle and breaking. While high-temperature threadlocker derivatives exist, typical Loctite-branded threadlocker (and similar products) would not appear to be able to stand the heat of a typical soldering iron.

This soldering iron hack isn’t the first we’ve featured on Hackaday – check out this method on removing enamel from magnet wire. If you’re not too squeamish, also check out our thoughts on soldering iron cauterization.

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Recharged Dehumidifier Put Back Into Service

September 19, 2021 by Tom Nardi 39 Comments

For the average consumer, repairing relatively low-cost home devices such as microwaves and TVs just isn’t economically viable. You can hardly blame them when the repair bill could easily be higher than the cost of just buying a new model. Luckily for folks like us, that means you can often find cheap or even free appliances on the second hand market that can be brought back online with a bit of troubleshooting and some spare parts.

Take for example the non-functional dehumidifier [HowToLou] recently came across. You probably couldn’t find a professional repair shop that would be willing to bother with one of these things if you tried, but as he shows in the video below, that doesn’t mean the DIY’er can’t run through some probable failure modes and get the unit back up and running. As a bonus, he also walks viewers through how your typical compressor-based dehumidifier operates.

Beyond the lack of water in the collection compartment, the first sign that something was wrong with this dehumidifier was that the compressor wasn’t running. Upon closer inspection, [HowToLou] determined that the thermal cut-off switch had failed and was stuck open. Luckily it had a visible part number so he could order a replacement, and in the meantime, all he had to do was cut the switch out of the circuit and wire up the compressor’s power directly.

Unfortunately, even with the compressor running, no water was being collected. Noticing that the evaporator coils weren’t getting very cold, [HowToLou] thought the unit might be low on refrigerant. Usually these systems aren’t meant to be recharged, but with a clever piercing tap valve, you can add a quick-connect port to the low pressure side. This particular dehumidifier happened to be filled with the same R134a used in automotive A/C systems, so a quick trip to the auto parts store got him a can of refrigerant complete with a handy pressure gauge.

After getting juiced up, [HowToLou] shows ice forming on the coils and plenty of water getting dumped into the tank. Automotive A/C refill cans usually include some substance to stop or reduce leaks in the system, so hopefully this will end up being a long-term fix. It might not be the most elaborate dehumidifier repair we’ve ever seen, but it’s certainly the most approachable. If you ever see one of these things laying on the side of the road, maybe you should pick it up and see what ails it.

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Laptop Gets Fixed By Simply Removing Problem Component

September 15, 2021 by Donald Papp 30 Comments

We wouldn’t go so far as to say “don’t try this at home”, but the way [Troy] brought an expensive (but out of warranty) laptop back to life is interesting, even if it shouldn’t be anyone’s Plan A for repair work.

It started with a friend’s Alienware laptop that would only boot to a black screen and get very hot in the process. With the help of a thermal imaging camera and some schematics, [Troy] was able to see that one of the closely-spaced MOSFETs in the power supply appeared to be the culprit. Swapping the power MOSFETs out with replacements seemed a reasonable approach, so armed with a hot air rework station he got to work. But that’s where problems began.

The desoldering process was far from clean, in part because the laptop’s multi-layer PCB had excellent thermal management, sucking away heat nearly as fast as [Troy]’s hot air gun could lay it down. It ended up being a messy slog of a job that damaged some of the pads. As a result, the prospects of soldering on a replacement was not looking good. But reviewing the schematic and pondering the situation gave [Troy] an idea.

An open laptop showing a diagnostic tool on the screen — One expensive laptop, brought back to service.

According to the schematic, the two MOSFETs (at least one of which was faulty) had parallel counterparts on the other side of the board. This is typically done to increase capacity and spread the thermal load somewhat. However, according to the current calculations on the schematic, these parts are expected to handle about 20 A in total, but the datasheets show that each of the MOSFETs could handle that kind of current easily (as long as heat sinking could keep up.) In theory, the laptop didn’t need the extra capacity.

Could the laptop “just work” now that the faulty part had simply been removed? [Troy] and his friend [Mike] were willing to give it a shot, so after cleaning up the mess as best they could, they powered the laptop on, and to their mild surprise, everything worked! Some stress testing with intensive gaming showed that the thermal problems were a thing of the past.

Simply removing a part may not be the best overall repair strategy, but much like shrinking a hot air rework station by simply cutting it in half, it’s hard to argue with results.