How to use a solder sucker

If you ever venture into the world of electronics repair then you'll need to be able to remove components soldered onto a circuit board. There are different ways to accomplish this. By far the best is desoldering tool like the Hakko 808. These are basically a soldering iron and a vacuum pump in one tool. It melts the solder then sucks it out of the joint. Very effective, but also very expensive.

There are less expensive options out there. Solder wick (a.k.a. desoldering braid) is probably the cheapest. This is basically a small spool of braided copper wire. You put the braid on the solder to be removed and heat both with a soldering iron. As the solder melts it's literally wicked into the desoldering braid.

The other inexpensive way to remove solder is using a tool called a solder sucker. A solder sucker has a spring-loaded plunger that when released creates a small vacuum effect through the nozzle. The theory behind a solder sucker is simple, but getting them to work is a different matter. I've found two different approaches to using a solder sucker.

The first is to use your soldering iron to melt the solder and at the same time hold the tip of the solder sucker close to the joint. Then in one quick motion pull the soldering iron away, put the tip of the solder sucker over the joint, and press the button to release the plunger. This technique works, but it's very difficult to get it just right. The problem is you have only a fraction of a second to suck up the molten solder before it cools and solidifies. Using this method I found it sometimes took half a dozen attempts before I was successful.

The second approach is one I stumbled upon be accident but works very well. First use your soldering iron to melt the solder to be removed. Next, add still more solder to the joint. The goal is to create a relatively large blob of molten solder. Now bring in the solder sucker and as soon as the tip of the solder sucker is touching the molten solder press the button. Do NOT remove the soldering iron, leave it there. Because the soldering iron remains on the joint the solder remains molten. Molten solder, like water, has surface tension which means it will stick together. So once some of the solder starts up the tip into the solder sucker, the rest of the solder will follow it. I find this method to work very well for removing solder. It usually removes all the solder on the first try.

Now this technique may not work well if you don't have a small soldering iron tip. I would suggest you experiment first on some junk circuit boards. Good luck and happy repairing.

Elenco XP-720K

I recently built the Elenco XP-720K, a bench variable DC power supply that comes in kit form. This is my mini-review of that kit and the process.

My first impression of the kit was of the quality. For a relatively small device it had a lot of weight. The metal case for the power supply is from thick metal, not cheap and flimsy. The painting on the case is very nice, and all the components for the inside are of good quality as well. The instructions are clear and easy to follow. All and all it was a fun kit to build.

As I built the kit I didn't photographically document every step of the way, but if you want to check out pictures of someone else building the kit go here.

I did make several changes or "mods" to the design.

1. I replaced the provided potentiometers with some Bourns 10-turn pots (3590S-2-202L). With more turns I have greater control over accuracy. I can easily dial the output power to within 2 thousandths of a volt. I could have added some "fine-tuning" pots in series with these pots for greater accuracy, but I don't need that level of accuracy.
   
2. In addition to the new pots, I used metal knurled knobs from Kilo (OEJL-63-4-5).
   
3. I covered the connections with the voltage regulators in heat shrink tubing to prevent shorts.
   
4. Instead of the provided capacitors, I ordered new high-quality low-ESR Panasonic brand capacitors rated for power supply use. With these high-quality caps the power supply should run for a long time.
   

Here are some pictures of the changes I made to the original design.






If I had to do this over I think there is only one change I would make. The new knobs I used were 5/8" in diameter. I think I would use larger 3/4" or even 1" diameter.

Even though I'm very pleased with this kit, I can think of some improvements I would suggest to Elenco.

• The traces and the pads on the circuit board are too large. I suspect this is to make it easier for a beginner to solder, but it actually does the opposite. Because the there is so much copper on the board, it takes longer to heat the copper to get the solder to flow properly. So this actually makes it harder to solder.
  
• Soldering the 12 wires onto the voltage regulators was not the easiest. If there were some sort of clip to slide onto the regulators, or if the regulators were soldered onto a second board with a ribbon cable connector between them, it would make assembly easier would help in reliability.
  
• Use bridge rectifiers instead of 4 individual diodes. Fewer solder connections and would be quicker and easier.
  
• Offer a model that includes a built-in display for voltage. Always having to use a multimeter to dial-in the voltage will get old fast.
  
• Offer a model that is based around the switch-mode power supply design versus the linear design of the XP-720K. Sure it would cost more, but it would be more efficient and would be even more fun to build.
  

The Elenco XP-720K is a great kit and a useful product once complete. If you find yourself in need of a variable DC power supply, consider this product (or the smaller XP-15K).

Electrical surges addendum

In my last post I talked about electrical surges, how devices like vacuums generate them and how good-quality surge protectors guard against them. I can already see it, someone who it read is thinking "are you saying that a vacuum on the same circuit as a TV or computer without a surge protector would mean instant damage to the TV/computer?" Surely you can't be making that claim, because I've done just that before and the TV/computer still works, so your claims are false. Well, I don't claim this scenario will always result in damage to the TV/computer, but if you repeat this scenario eventually it will fail. Let me explain why this is.

The electricity coming into your house is AC (alternating current). The problem is very few devices use AC, most require DC (direct current). Therefore, every TV, computer, radio, etc. has an AC to DC power supply. Inside that power supply is the same protection circuitry located in a surge protector. That's why the device does not fail after one power spike.

"If the TV/computer protects itself against surges, why bother with a surge protector?" I'm glad you asked. The first reason is what I said in the last post - the circuity can only protect against X number of surges, after that it's useless. So if you don't use a surge protector eventually the TV will break and you'll have to replace or repair it, but if you use a surge protector you can replace the surge protector for much cheaper. The second reason is because the TV/computer probably contains a low-level of protection, i.e. it only protects against a low number of joules of energy. A good-quality surge protector will protect against more joules.

Also, if the TV/computer is on or off during the surge makes little difference. The device is probably more susceptible to surges when powered on, but may still be overloaded when turned off. The only way to truly protect it is by disconnecting it from the socket.

One final thing I'll mention is polarized AC plugs. You've probably noticed some AC plugs are polarized (one connector is larger than the other). If AC flows in both directions why is the plug polarized? The answer has to do with the protection circuitry. Manufactures put the protection circuitry on the "hot" wire and leave the "neutral" wire unprotected. Thus the polarized plug ensures the protection circuity is properly protecting the device. Manufactures could protect both the hot and neutral (and indeed some do), but this costs more money. If you've ever "forced" a polarized plug to fit the wrong way, the device was no longer protected. Also, if you have a wiring fault in your home, the device is unprotected as surges could come up the neutral wire. Both of these are still more reasons to use a good-quality surge protector. A good surge protector protects hot, neutral, and ground.

Electrical surges

Recently I learned some very useful info related to electrical surges and surge protection. An electrical surge can be described as additional voltage and/or current above and beyond the expected amounts. These surges can come from two main sources, outside your house (e.g. lightning strike) or inside your house (more on that later). Regardless of the source, a surge could easily damage newer electronic devices which are very sensitive to surges. Despite common believe, fuses do not protected against surges. Fuses only protect against too much current (amperes) not too much voltage.

Before I discuss protection, I wanted to talk a little more about surge sources. It's easy to understand surges external to your house - the most obvious example would be lightning strike. But surges generated inside your house are a little more difficult to understand. I won't go into the electrical science, but the short answer is any large inductive device has the potential to create voltage surges. The most common inductive device capable of generating large surges is large electrical motors. Whenever you turn off an electrical motor it creates a voltage surge on the household circuit on which it's connected. And yes you read that correctly, the surge is created after the motor is turned off, not before or during. This is one of the main reasons why refrigerators, washer and dryer, and air conditioners are typically on their own circuit. If other appliances were connected to the same circuit as these appliances they would get a surge every single time the motor switches off. There is however one large motor in your house which is not on a dedicated circuit - your vacuum cleaner. Vacuum cleaners have deceptively large powerful motors in them. It's not uncommon for a vacuum cleaner to pull 12 amps or more. That is a lot of power! So if you plug your vacuum cleaner into the same circuit as your expensive TV or computer, when you turn the vacuum off you're subjecting those devices to a surge. After vacuum cleaners, the next biggest source of surges would have to be fans (both those plugged into the wall and ceiling fans).

Now that we know the sources of surges, what can we do about it? Obvious you say, we use a surge protector. Well yes and no. The answer is a surge protector, but not all surge protectors are created equal. Most people refer to the following item as a surge protector:

This may be a surge protector, but chances are good it's just a power strip. A power strip is nothing more than multiple outlets with an on/off switch. It offers zero protection against over-voltage or over-current. A true surge protector is usually a little larger in size and costs more. The only way to tell them apart is to either open them up and look on the inside, or read the specs that came with the product. Chances are if you spent less than $10 or $20 on it, then it's probably a power strip not a surge protector. Probably the most respected name is APC, they make high-quality devices. There are other good brands as well.

Even if you have good-quality surge protectors, you may not be covered. As it turns out surge protectors breakdown over time. In effect they can only protect against a certain number of surges before they fail. When they fail the surge protector will still provide power, but the surge protection aspect is gone.

So what's the take-away from all this.

1. Identify the circuits on your house with expensive electronic items (TVs, computers, etc.). Never use a vacuum cleaner on these circuits. Also, if possible avoid fans on these circuits.
   
2. Buy and use good quality surge protectors NOT power strips.
   
3. Even if you have good-quality surge protectors, don't assume you're safe as they have a limited lifespan.
   

If you really want to know more on this, I recommend you watch this video in which he does a great job of explaining inductive spikes. Also, the following article dissects a surge protector and goes into more details.

Electronic parts

Lately I've been doing a lot of electronics repair. It's kind of a fun little hobby. Say your flat-panel computer monitor dies on you. You could throw it away, or for about $4 and 5 minutes of time you can repair it. Of course, you need to know how and what to repair, and I'm not really going to cover that here. The other thing you need is replacement parts, which is what I wanted to talk about today.

Say you need a diode, capacitor, resistor, etc. to repair an item. You could go down to your local Radio Shack or other electronics supply shop, but I would recommend against it. First, these places have a very limited supply, and second if you buy online you can get higher quality components. Also, the prices online are cheaper, although when you add in shipping the final cost will be about the same.

I recommend digikey.com. There are other sites, but digikey is my preferred supplier. Let's say you're looking for a 680 uF 16 volt capacitor (like this):

Knowing how to find this on digikey's site can be overwhelming the first time you try it.

1. Enter "capacitor" in the search box on digikey's site and hit enter.
   
2. The next screen shows all the different type of capactitors (e.g. ceramic, tantalum, etc.). In this case we're looking for "aluminum" so click on that. (BTW: you just need to learn that aluminum is another name for standard electrolytic capacitors.)
   
3. On the next screen, you need to filter down the selection. Under capacitance select "680uF." Under voltage select "16V." Under mounting type select "through hole." Finally check "in stock" and click Apply Filters.
   
4. This filtered it down to 17 choices. From here you can find the one you want, or further filter using manufacture, dimensions, etc.
   

Depending on which one you select, the capacitor is only .40 - .75 plus shipping (which is cheap for small orders). Once you learn to navigate digikey's site they have some really cool stuff such as thousands of LEDs of ever shape and color. If you're into electronics repair, hobby kit building, RC planes/cars, etc. give digikey a look, they are very useful.

Smart TVs - more like stupid TVs

Ok, today's post is more of a rant than anything. If you've even considered buying a TV in the past year than you know that most new TVs are what they call "Smart TVs." Basically the TV is Internet-enabled so you can watch content from the web as well as standard TV programs. At home I own two of these Smart TVs. But in my opinion they should be called "Stupid TVs." The "Internet" feature to these TVs is all but worthless.

When you think of the Internet, there is a ton of great free content to watch. And I'm not just talking about YouTube. Some of the great free sources of content are Hulu, ABC, NBC, CBS, Fox, and PBS. There are a lot more, but with just those 6 there is more free content then you could ever hope to watch. So, how many of these 6 Internet sites do you think you can watch using a Smart TV? The answer is ZERO! It's very frustrating too because you can use a computer and visit all these sites and watch free content all day long. But you cannot use a TV to view free content from these sites.

I don't blame TV manufactures either. The problem is the content providers (the above 6). They have decided in their infinite stupidity that we should not be able to watch this content from our TV (again, despite the fact that we can watch it from a computer, even a computer connected to a TV).

As far as I can tell the only uses for a Smart TV right now are the following:

1. If you have a Hulu Plus, Vudu, Amazon Prime, and/or Netflix accounts (all of which cost money), you can watch that on your TV.
   
2. I have found a single source of free content on my Smart TV, Revision3. Revision3 offers tons of great free programming, all of it is technology/computer related. If you're into that you'll enjoy their content, otherwise this channel won't be for you. My personal favorites are Tekzilla, Hak5, and the Ben Heck Show.
   

Well I'm just hoping these sites will finally realize how arbitrary and stupid their decisions are and allow us to starting watching this content. If not, I may build a HTPC to get around this problem.

The rechargeable battery myth

It's common knowledge that older rechargeable batteries have a limited lifetime. They can only be charged so many times before they won't "hold a charge" any more. This is often referred to as the battery "memory effect." This was a well known problem with Nickle-Cadmium (NiCad) and Nickle-Metal Hydride (NiMH). But for some reason, a lot of people believe this is not a problem with Lithium-ion batteries. This is the "myth" that I'm referring to, that Lithium-ion batteries do not suffer from this problem.

Unfortunately, Lithium-ion batteries do suffer from this problem. The good news is they are less susceptible than NiCad or NiMH, but the problem does still exist. If you don't believe me, find a 5 year-old laptop with Lithium-ion batteries and see how good a charge they hold - chances are they only hold a fraction of their initial charge. I won't get into the technical reasons behind why rechargeable batteries suffer this problem. But I wanted to debunk this myth about Lithium-ion batteries.

There's nothing you can do to prevent this from occurring to a battery, but there are several things you can do to slow it down. I've read a lot of crazy things on the Internet such as freezing and thawing your batteries to "restore" them to working order. These various "techniques" sound far-fetched to me. But one technique that does work is to be mindful of your battery, and how and when you charge it. The best thing you can do is run the battery almost until it's dead, then fully charge the battery back up. The worst thing you could do is run the battery for a few minutes and then charge it again.

One of the most common battery-powered devices are laptop computers. So the best way to maximum the life of your laptop battery is to run the battery until it is very low; then and only then do you charge the battery. And don't stop the charge cycle until the battery is fully charged. If you want/need to run the laptop off AC power before the battery is discharged, then remove the battery while running off AC power. By doing this you will extend the life of your battery.

Bad news for LCD TV owners

I'm afraid I have some bad news for owners of LCD TVs (and computer monitors). Especially if your panel is slightly older. The expected lifespan of your TV/monitor is probably far less than you would like it to be.

To some people a TV is a consumable, something to be replaced every couple of years. Think of all the extra money spent in America replacing several year old TVs, not to mention the eventual landfill space. Of course, manufactures love these people as it increases their profit. Think of your parents or your grandparents, how long did their TV last? 15 years, 20 years, or longer? But there is no way most newer TVs will last that long. In fact, I would expect the average lifespan to be about 5 years.

What's the problem you ask? It has to do with what's called the backlight system. Most LCD TVs use cold cathode fluorescent lamps (CCFLs) as the backlight. In a nutshell, a CCFL is a small fluorescent light, just like the ones you see in garages and warehouses. But CCFLs, like any light bulb, burn out in time. Once a CCFL burns out, the image on the TV screen goes black. You can replace the CCFLs with new ones, effectively "changing a light bulb" to fix the problem. But very few TVs are designed for this work to happen. When manufactures build TVs they do not design a way for these backlights to be changed. So what you're left with is a TV with a burned out light bulb that is useless.

This is just bad design in my opinion. Would you buy a car that the engine could not be serviced? Would you buy a bag vacuum cleaner without replaceable bags? No, of course not.

The good news is TVs are starting to come with LED backlights. LEDs are solid-state electronics that have a much longer lifespan. Also, LED TVs are thinner, lighter, produce less heat, and consumer less electricity than CCFL TVs. So if you're in the market for a new TV, I would strongly encourage you to get an LED TV. They cost more, but in the long run it will save you money.

General electronics repair tips

Today I wanted to give some general repair tips for electronics. I've previously mentioned the two most common reasons for failure are lead-free solder and bad capacitors.

Lead-Free Solder:

Unfortunately diagnosing lead-free solder is not easy. Probably the correct way is to investigate each and every solder joint on the circuit board. You could use a multimeter to check it electronically and/or a visual inspection using magnification. But this can be time consuming considering the number of solder joints on a board. Obviously the first step is to verify the board has lead-free solder. This can be done is several ways:

1. Visual appearance - lead-free solder has a flat or non-glossy appearance whereas leaded solder is shinny.


2. Age of the item - the older it is the less likely it is to have lead-free solder. Before the mid 2000s and it's probably more likely to be leaded, after the mid 2000s and it's more likely to be lead-free solder.


3. Symbols - look for lead-free symbols (like "RoHS") on either the board itself or the case. If you find this symbol it for sure has lead-free solder, but the absence of this symbol does not necessarily mean leaded solder.

IF the board uses lead-free solder and IF you can't find anything else wrong with it, then lead-free solder is likely the problem. But how do you fix it? I know the theory, although I don't speak from personal experience. Ultimately you need to remelt the solder to repair the cracks. So you need to subject all or part of the board to heat - up to 260 C (500 F). The official way to do this is using a hot air rework station. But this is a specialized tool that few people own. If you own a heat gun you can use that. You can even put the board in the oven, or if the board is one-sided you can put it onto a griddle. You need to heat the affected part of the board up to 260 C then back down. Too much heat will damage the board. Also, be aware some of the components on the board (like plastics) may burn, so you might need to cover them with foil to shield them from the heat.

Bad Capacitors:

A bad capacitor can be easier to identify and relatively easy to repair. Often times you can visually detect when a capacitor has failed. It may bulge on the top, even start to leak from the inside (see pictures below). Unfortunately not all bad caps bulge, so you may need a special cap tester. But if you see a bulging cap you know it's bad. Replacing a bad cap is fairly easy, all you need is a soldering iron and the replacement part. To get the replacement part you need to know two things, the rating and the voltage. These will be written on the side of the bad capacitor. For example 830uF 25V. This is 830 uF (or microfarads) at 25 volts. When you order replacement parts get the exact same farad number, as for the volts you can get the same or a little higher. You can try your local electronics shop (e.g. RadioShack), but I'll tell you right now the chances they will have exactly what you need are slim. Instead order online, digikey.com and mouser.com are both great sites specializing in these parts. And these replacement parts are cheap to. Cost depends on the rating of the capacitor, but each component will probably cost you less than a dollar. So you could replace all the capacitors in a piece of electronics for only a few dollars.

Both of these repair techniques work with solder and soldering tools like irons. I suggest you watch some of the videos on youtube by "CuriousInventor" - he has great tutorials.

Taking apart electronics

Yesterday I mentioned common reasons for failure in electronics. Before I give general tips on how to diagnose and try and repair them, I wanted to give some tips on working with electronics.

First, you'll need to be able to take apart the electronics, which can be more of a challenge than you think. Many newer electronics are not designed to be taken apart easily. If you're lucky, your item has screws holding it together. If not, you have plastic tabs holding it together. The tabs are a pain to get apart, you need to slowly pry them apart using a small screwdriver. And in doing so you're pretty much guaranteed to scar the plastic in at least one place.

Once you have the item opened up, you need to be comfortable with electricity. Most people have gotten a shock from a switch or light in their life. It's not fun, but it's not dangerous - mainly because it's alternating current. However most electronics use direct current which is more dangerous. Also, some electronics have high voltage and/or high current inside of them which is dangerous as well. Obviously, if you're not comfortable then don't proceed. Trying to fix a $500 TV is not worth serious injury.

When working on electronics, sometimes you need to work on them while they are plugged in and turned on. Obviously this means live electricity. But DO NOT ASSUME an unplugged piece of electronics is safe to work on. I know of two potential dangers. First is the aforementioned capacitors which can hold a charge. It's not uncommon to find capacitors rated to 150V inside electronics like a TV or stereo, which means that capacitor could potentially hold 150V of electricity inside it, even when the device is off and unplugged. However, if you use a screwdriver to short out the two leads this discharges the capacitor and makes it safe. The other danger I'm aware of is what's called a flyback transformer which is found on tube TVs and computer monitors. This is in the form of a suction cup attached to the back of the tube. I guess the flyback transformer can hold thousands of volts. Again, it must be carefully removed and shorted out if you plan on working on an old tube TV or monitor.

Me, I've very new and inexperienced when it comes to electronics repair, but I am comfortable working around electronics and electricity. But since I lack experience I've given myself 3 guidelines.

1. I will not work on old TVs and computer monitors because of the flyback transformer.


2. I will not work on microwave ovens, they contain both high voltage and high current which is an extreme danger and could very easily kill you.


3. Whenever I work on electronics, I will short out any capacitors to remove any lingering charge.

The last tip is buy and learn how to use a multimeter. A multimeter is an essential tool in electronics repair. You can buy them for as little as $10, a decent meter in the $50 range, and a good meter runs $100 or more.

Failing electronics

One thing that interests me lately is repairing electronics, or at least trying to. I thought it might be interested to blog about the various projects I attempted and their outcome.

Before I talk about the projects I've been working on, I wanted to elaborate on why electronics seem to have shorter lifespans. Many people have noticed that electronics lately seem to die within about 5 years. Why is that? A lot of people probably have a VCR at home from the 80s that still works fine, so why is it their DVD player from just a few years ago has died? The answer to that is complicated. I'm sure part of it is because most electronics manufactures don't manufacture their own products anymore. As I talked about in previous posts, just as Dell doesn't actually make their computers, the same is true of Toshiba and their TVs, or a DVD player from LG. It's just the way the industry works these days.

But I think the 2 single greatest problems resulting in electronics failure are bad capacitors and lead-free solder.

1. In 2006 the European Union started enforcing the RoHS (Restriction of Hazardous Substances) directive. As the name implies, the intent is to reduce the amount of hazardous substances in electronics. One of the changes required is the use of lead-free solders. Most electronics solder is a mixture of tin and lead. But the use of lead-free solders has caused to a lot of problems. Lead-free solders are a lot more brittle, over time they crack which can break the electrical connection. Even if the electronic device doesn't move (like a TV mounted on the wall), the expansion and contraction as the device heats up and cools is enough to cause cracking. Another problem caused by lead-free solder is called tin-whiskers. The solder joint actually begins to grow tin crystals which look a lot like microscopic whiskers or hairs. If these whiskers come in contact with a nearby piece of metal, it can cause a short. There is a reason why they added lead to solder in the first place, the lead prevents these problems from occurring. Admittedly they are getting better at the recipes of lead-free solder they use. Electronics manufactured around 2005 - 2007 seem to be most susceptible. Only time will tell if the new lead-free solder formulas work better.


2. The second common failure point for electronics is a bad capacitor. A capacitor is a small electronics component. The problem here is a certain type of capacitor called an electrolitic capacitor. If you've ever looked at a circuit board, they look like small cylinders with a shiny metal top. From what I've heard the problem is a few years ago a bunch of Chinese companies started producing very inexpensive electrolitic capacitor which, because of their price, were quickly adopted by manufactures and made their way into most electronics. But these electrolitic capacitors were inferior to higher cost Japanese electrolitic capacitors and would fail in time. But no one knew this at the time. If you tested a Chinese capacitor and a Japanese capacitor, they both checked out. But the Chinese capacitors had a high failure rate in the 3 - 5 year range.

Next time I'll talk more about these two problems, and even how to diagnose and fix them.