Sachi Trifles with Electricity

[SachikoMaeda]

As some of you may remember, I like to fix up old Macs as a hobby. Fixing computers is my current job, so my resources have expanded greatly. I recently even started soldering recently. It's a lot funner than I thought it would be~

Electricity is a vengeful SOB who is not to be trifled with.
But I'm a feather rustler, so I do quite love to mess with it.

You can follow my current repair job over here. Let me make note that this job is dangerous if you don't know what you're doing. Why you ask? Well, it'll make you appreciate that flat screen you're more than likely looking at right now.

Those old computer monitors and TVs we used to have displayed their image through a cathode ray tube or CRT for short. If you want to read the technical stuff, give this page a looksie. Sound fun, yeah? One wrong move and I can break the tube, causing the vacuum seal to be broken. Hit it hard enough and it'll explode-- well, technically implode. And while I'm worrying about all that, I have to know for certain that it isn't holding a charge. It won't be lethal on one this size, but it will hurt. Bad.

If you ever pick up the hobby of full on repairs like this, do your research. Know how to diagnose a problem, ask questions, and most importantly, respect and understand electricity. Even if it's a little bit of simple hardware repair like adding in RAM to your computer. All it takes is one little static shock and you could fry a component.

So, why share all this? Because I just shocked myself. And it hurt. A lot. How? Testing the CRT I just finished repairing the power board to. Hooked it all up, plugged it in, turned it on, and stupidly touched one of the metal joints of the flyback transformer (that doohickey that creates the high voltages for the CRT). I touched it only for a second but my middle finger all the way up my arm still hurts. You don't quite run the same issues like that when repairing the nice flat screens. Their power boards don't require the high voltages a CRT requires. So if you do shock yourself, it won't hurt as bad.

So in short, if you play with electricity, pay attention. I've accidentally shocked myself plugging in my laptop by touching a metal hinge and unknowingly touching the metal plug as I stuck it in the wall. So be safe out there and don't stay too grounded.

[SachikoMaeda]

Today, I feel like talking about capacitors. What they're for, why they're good, and why they suck.




Capacitors are a vital part of the circuitry of your computer. Open up your computer and I can ensure you that you'll see at least four of them. So what are those cylinders and what are they used for? In simple terms, capacitors store an electric charge. They kinda work like little mini batteries that lose their charge slowly after being turned off. There's multiple types of capacitors all for different types of uses in a circuit. On our motherboards, they work with multiple components in ensuring the electricity that is your data running smoothly.

So what happens when these fail? Physically, you may see the capacitor's top bulge. In time that bulging can cause the top of it to pop, leaking the electrolytic gobbledegook all over your motherboard. If you're using your computer in this state, you may notice a few little random errors at first. Maybe your computer will slow down, take longer to start, or ultimately not power on at all. But all of those things might not happen. You might get concerned if you start to notice these sorts of issues. "Maybe I picked up some malware along the way," you might think. You run all sorts of scans with your most trusted tools only to still have all these problems. Your system is unstable due to the failing circuitry.

This is a common issue I see here in the shop. If a computer runs near constantly, not dusted regularly, improperly stored, and/or maybe it's an older computer. Sometimes it's worth to open the computer's case and take a look at those boards. Not just the motherboard, but also any graphics cards! The older the system is, the more prone it is to these sorts of failures.

Working in restoring old Macs like I do for a hobby, it's almost always advised to replace the capacitors. I'm still working on finding the proper capacitors to put on the board.

So, long story short, part of maintaining your computer should include hardware checkups. Open that case, give it a good dusting, check those caps, and make sure that any leaking caps are properly replaced. If you're not confident in handling caps, I can answer any questions or point you to someone online who can replace them. Who knows, I might be able to fix it for you. So, as I said before, be safe out there and don't stay too grounded!

[CappnRob]

[Sorum]

Off topic: WELCOME BACK!

On-topic: Don't shock yourself or otherwise you will become that electricity guy from amazing spiderman 2.

[Nymus]

omelette du fromage

[SachikoMaeda]

THE THING THE THING THE THING IT'S THE THING!

Today's thing I'll talk about is the difference between a Direct Current and Alternating Current. I have a whole year or knowledge dedicated just to both. Trying to cram it all in with electromagnetism will take a novel. And I'm not paid to write a novel. So as always, I'll try to keep it simple.

Direct Current. This describes an electrical flow that never changes its polarity. Positive and negative remain the same. The easiest way to imagine a direct current is to think of a battery. Batteries always supply a DC current. Their position is fixed with a clearly marked positive and negative terminal. The electricity will always flow from positive to negative. With a DC circuit, you can tell which direction the electric current is going. All of your internal components of a computer run off of DC except for the power supply, but we'll get to that in a moment.

Alternating Current. This is what the power grid runs off of. Imagine a large turbine constantly changing its polarity to generate large amounts of electricity. Alternating current is constantly changing its polarity. If it were to be tested with an oscilloscope you would see a wave pattern. That's a visual of the constant polarity change. How fast it changes is determined by frequency. AC is ideal for something that requires more power. The water heater, old CRT TVs, the stove, refrigerator, even your car's alternator produces an alternating current.

So what about your computer's power supply? How does a current go from AC to DC? I could go all day discussing Ohm's Law and getting super technical, but I don't plan to bore you. This is the easiest way I see to explain it. For the most part, your power supply unit (usually shortened to PSU) consists of diodes, capacitors, resistors, and regulators. Their job is to straighten out the polarity as the AC travels through the circuit. While the computer isn't pure DC, it brings the AC to an acceptable level to keep from frying components.

Why's it great to know the difference? In the common home, AC carries higher amounts of energy than DC. Why do I continue to point this out? Because AC is usually a lot more dangerous than DC. If you have someone come to your house and install cable or work on your air conditioner, they risk death under your house. How? If you touch the wrong cable, you're grounded. All that electricity will flow through you until you're crispier than a blackened catfish. Well... That might be a little exaggerated, but these can kill. The CDC has a few reports like this one explaining how this can happen. Under the house, in the walls, up on those power lines, those people risk their lives to ensure we have the nice, cozy places we're used to.

It's another reminder that you should always play safe. Don't play with your house's wiring. Let a pro handle it. Unless you are a pro, then have at it. Maybe we can talk about electricity. I'm still a little rusty on the basics, so maybe you could even point out any errors I make in my little discussions. Anyways, I gotta go dig up some schematics for my Macintosh Classic. Gotta test components. So stay safe and don't get too grounded!

[Ural]