PCB Solder Pad Repair & Cleanup

What do you do when your motherboard is covered in electrolytic grime, has damaged pads and traces that are falling apart? You call [RetroGameModz] to work their magic with epoxy and solder.

While this video is a bit old, involved repair videos never go out of style. What makes this video really special is that it breaks from the common trend of “watch me solder in silence” (or it’s close cousin, “watch me solder to loud music”). Instead, [RetroGameModz] walks you through what they’re doing, step by step in their repair of a motherboard. And boy do they have their work cut out for them: the motherboard they’re working on has definitely seen better days. Specifically, it was better before corrosion from a leaking electrolytic capacitor and the well-meaning touch of its owner.

After a quick review of the damage, all of the components are removed from the battle zone. Then the cleaning begins, taking special precautions not to rip pads up. After everything’s cleaned up, things get really interesting. [RetroGameModz] starts to make their own pads from raw copper using the old pads as templates to replace the missing ones on the motherboard. After a bit of epoxy, it’s hard to tell that the pads were handmade, they fit in so well.

This epoxy trick is also used to deal with some heavily damaged traces, cool! During this repair, [RetroGameModz] used an epoxy that is heat resistant up to 315°C for 60 seconds. If you ever find any kind of epoxy on the market that is specified to be heat resistant up to more than 315°C, [RetroGameModz] would be quite happy if you could leave some info in the comment section, as they’ve found high-temperature epoxies quite difficult to source.

This goes to show that some repairs really should be done by professionals. [RetroGameModz] surely agrees, stating that “If you are not a repair technician and your motherboard has stopped working, it would be in the best of your own interest not to attempt a repair that you really cannot handle.” Good advice. But, we can never resist trying to fix things ourselves before handing things off to the more experienced. Call it a vice, or a virtue; we’ll call it fun.

What do you think? Are there some repairs you rely on technicians for? Or do you fix everything yourself? Let us know in the comments.

Continue reading “PCB Solder Pad Repair & Cleanup”

Casting Cylinder Heads Out Of JB Weld

Like friendship, JB Weld is magic. Rumors persist of shade tree mechanics in the Yukon repairing cracked engine blocks with JB Weld, and last month this theory was proved correct. [Project Farm] over on YouTube took a grinder to the head of a lawnmower engine, filled the gouge with JB Weld, and ran the engine for twenty minutes.

However, as with anything mechanical that doesn’t have a foul-mouthed Canadian in it, arguments ensued. ‘This was not a true test of JB Weld repairing a cracked engine block’, claimed Internet commenters, ‘I won’t even watch the video because the idea alone is click bait.’

Now, [Project Farm] is back at it. Is it possible to use JB Weld to cast an entire cylinder head for a lawnmower? It sure is. With a cast epoxy cylinder head, this engine will run for just long enough for a proof of concept.

This experiment began by casting a single monolithic block of JB Weld that’s a bit larger than the cylinder head for a lawnmower. After curing, this JB Brick was surfaced on both sides with a belt sander. No, there was no vacuum chamber or any other techniques used by people who work with epoxies for a living. With the brick surfaced, the head gasket was used to place the bolt holes, the brick was tapped for a spark plug, and a bit of the inside was Dremeled out for the valves.

After attaching the JB Weld cylinder head to a lawnmower, [Project Farm] ran the lawnmower for about a minute. Is this a proof of concept? Yes. Did it work? Absolutely. Is it the ultimate test of JB Weld and the myth of the cracked engine block? Unfortunately, no. For that, someone will have to build a real engine entirely out of JB Weld. Until then, just check out the video below.

Continue reading “Casting Cylinder Heads Out Of JB Weld”

JB Weld Fixes Cracked Cylinder Heads

There are persistent rumors that the main ingredient in JB Weld is magic. This two-part epoxy that you would normally find on a shelf next to your basic 5-minute epoxy, Titebond, various cyanoacrylates, and Gorilla glue is somehow different. Stories of ‘some guy’ in the Yukon using JB Weld on a cracked engine block abound. These stories are of course met with skepticism.

Now, finally, we have evidence you can use JB Weld to fix an engine. [Project Farm] over on YouTube gave it the ultimate test: he took the cylinder head off a lawnmower, took a grinder to the head, and patched the hole with JB Weld. The head had good compression, and the engine actually ran for 20 minutes before the test was concluded.

If this were a test of a field repair, it would be a test of an extremely crappy field repair. [Project Farm] made no attempt to ensure the piston didn’t make contact with the blob of JB Weld, and in fact, there was some slight knocking from the piston tapping against a blob of epoxy. Still, this repair worked.

While this serves as proof of the feasibility of repairing an engine block with JB Weld, there is one ultimate test of JB Weld epoxy: build an engine out of it. For years, I’ve been casting my leftover JB Weld into a small square plastic container. In a few more years, I’ll have a block of JB Weld ‘stock’, large enough to machine the parts for a small (.049 cc) glow engine, like what you would find in ye olde tymie model planes and cars. Will it work? I have no idea, but now I can’t wait to find out.

Continue reading “JB Weld Fixes Cracked Cylinder Heads”

Casting Machine Bases in Composite Epoxy

When you’re building a machine that needs to be accurate, you need to give it a nice solid base. A good base can lend strength to the machine to ensure its motions are accurate, as well as aid in damping vibrations that would impede performance. The problem is, it can be difficult to find a material that is both stiff and strong, and also a good damper of vibrations. Steel? Very stiff, very strong, terrible damper. Rubber? Great damper, strength leaves something to be desired. [Adam Bender] wanted to something strong that also damped vibrations, so developed a composite epoxy machine base.

[Adam] first takes us through the theory, referring to a graph of common materials showing loss coefficient plotted against stiffness. Once the theory is understood, [Adam] sets out to create a composite material with the best of both worlds – combining an aluminium base for stiffness and strength, with epoxy composite as a damper. It’s here where [Adam] begins experimenting, mixing the epoxy with sand, gravel, iron oxide and dyes, trying to find a mixture that casts easily with a good surface finish and minimum porosity.

With a mixture chosen, it’s then a matter of assembling the final mould, coating with release agent, and pouring in the mixture. The final result is impressive and a testament to [Adam]’s experimental process.

We’ve seen similar builds before — like this precision CNC built with epoxy granite — but detail in the documentation here is phenomenal.

Learn Some Plastic Techniques With This SNES WiiMote Mod

Not all hacks have to be deeply technical. Sometimes a good show of skill is just as impressive. [lyberty5] takes two completely different hunks of plastic and somehow epoxies them into a convincing and, most impressively, reliable chimera.

While the WiiMote’s motion controls certainly caused a lot of wordy debate on the Internet when it was debuted. While everyone and their grandmother who owned a game company rushed out to copy and out-innovate it once they saw Nintendo’s hoard of dragon gold. Most game designers had other thoughts about the concept, mostly that it wouldn’t do for a platformer. So the gamer caught in the middle of it all had to rotate their grip-optimized rectangle 90 degrees and blister their thumbs on tiny buttons to play. Continue reading “Learn Some Plastic Techniques With This SNES WiiMote Mod”

A Short Introduction to Staking and Potting

Staking and potting are not often used in the hobby electronics world, not really entering to the common vernacular. However, everyone who’s ever busted out a glue-gun to convince that dang wire that keeps coming loose to stay has done it.

However, as [Sean Thomas] touches on, staking is not necessarily as easy as a dob of hot glue. There is a method to the madness. [Sean] gives some examples in pictures, but also directs people to the excellent NASA standard methods for staking. It’s surprising how many unintuitive caveats there are to the proper technique.

Potting, or covering everything in epoxy forever, is a great way to get a waterproof, unserviceable, and practically mechanically invincible circuit. The big challenge in potting is picking the right material. A soft silicone, for example, might transfer an unexpected force to an unexpected section of the circuit and cause a mechanical failure. A nice hard epoxy may be too insulating and cause a thermal failure. The standard RTV from the big box store has acetic acid that will eat your components.

These two techniques that come in handy when you need them and worth the bit of reading it takes to get familiar. Have you used either in your own workshop? Let us know the application and the material/techniques you have tried in the comments below.

Homemade Capacitors Of A Mad Scientist

Once upon a time I was a real mad scientist. I was into non-conventional propulsion with the idea of somehow interacting with the quantum vacuum fluctuations, the zero point energy field. I was into it despite having only a vague understanding of what that was and without regard for how unlikely or impossible anyone said it was to interact with on a macro scale. But we all had to come from somewhere, and that was my introduction to the world of high voltages and homemade capacitors.

And along the way I made some pretty interesting, or different, capacitors which I’ll talk about here.

Large Wax Cylindrical Capacitor

As the photos show, this capacitor is fairly large, appearing like a thick chunk of paraffin wax sandwiched between two wood disks. Inside, the lead wires go to two aluminum flashing disks that are the capacitor plates spaced 2.5cm (1 inch) apart. But in between them the dielectric consists of seven more aluminum flashing disks separated by plain cotton sheets immersed in more paraffin wax. See, I told you these capacitors were different.

I won’t go into the reasoning behind the construction — it was all shot-in-the-dark ideas, backed by hope, unicorn hairs, and practically no theory. The interesting thing here was the experiment itself. It worked!

I sat the capacitor on top of a tall 4″ diameter ABS pipe which in turn sat on a digital scale on the floor. High voltage in the tens of kilovolts was put across the capacitor through thickly insulated wires. The power supply contained a flyback transformer and Cockcroft-Walton voltage multiplier at the HV side. As I dialed up the voltage, the scale showed a reducing weight. I had weight-loss!

But after a few hours of reversing polarities and flipping the capacitor the other way around and taking plenty of notes, I found the cause. The weight-loss happened only when the feed wires were oriented with the top one feeding downward as shown in the diagram, but there was no weight change when the top wire was oriented horizontally. I’d seen high voltage wires moving before and here it was again, producing what looked like weight-loss on the scale.

But that’s only one of the interesting capacitors I’ve made. After the break we get into gravitators, polysulfide and even barium titanate.

Continue reading “Homemade Capacitors Of A Mad Scientist”