Safety

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Electrocution

This little section of the Wiki can’t replace common sense, knowledge, and a healthy respect for the hazards we may encounter when doing DIY projects. Its intent is to offer you a place to start, to learn more about some of the safety issues you may encounter before you face them. The internet is a great tool to find the answers…please use it! If you’re in doubt about the safety of what you’re about to undertake, please take the time to work into it, learning as you go, and seek the advice of those with more experience. With the proper attitude, this hobby can be fun and rewarding as well as safe! As with all endeavors, putting one’s health and well-being first is the most important thing.

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

Common Risks and Common Warnings

In light of that fact, here are a few things that one can do to minimze the risks involved in DIY pedals and related gear.

Capacitors One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly.

Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

Shake Hands with Mr Electron

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

Soldering Hazards

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

Safety When Etching Printed Circuit Boards

When building many DIY projects, you might want to make your own printed circuit board. This leads to another safety and health issue…the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point you in the right direction to keep you safe.

The general consensus seems to be: if you are concerned about using etchants, which are acids and CAN burn you, you might want to explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags, then proceed with knowledge, caution, and respect!

BASIC SAFETY: When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry lab safety practices. Always work in a safe place free of obstacles/trip hazards that is WELL-VENTILATED (garage?), clear of objects that may be ruined by contact with the acid. Wear appropriate (old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Keep your face away from the etching container! Etchants and the metals that dissolve into them are poisonous: do not use containers, utensils and the like which will be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect for electricity in the presence of liquids that you always would.

Read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground, and keep it out of the trash…improper disposal could lead to serious environmental clean-up costs, unintended poisoning of driking water wells and the like!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. As with any DIY project, understanding what risks are present and having a plan to deal with them will help to ensure your safety and health as you enjoy this hobby.

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Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride Material Safety Data Sheet (MSDS) http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages: Easy to use, sold in premixed form. Fairly inexpensive and easy to find. Does a very good job etching.

Disadvantages: Can cause chemical burns! See MSDS for other health concerns. Stains almost everything it comes into contact with. Will corrode other metals. The chemicals dark reddish color makes it difficult to check etching progress.

Tips: Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil! Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark! http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more The reaction results in a foam-like substance being produced which dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, the reaction will overflow the container and cover your counter with ooze within 20 seconds or so. Keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life anything it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret. The thing about the etchant is that it may LOOK completely treated when it isn't. You may have just a small residual film at the bottom of the container, and when you dump a few tablespoons of soda on it, it starts foaming like crazy. You will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

Painting Safety

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

Ventilation: When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

Eye protection: Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

Fire Hazards: Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area to create a combustible atmosphere - remember to ventilate! Rags soaked in paints and solvents should be spread over a surface such as a workbench and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

Solvents: It was pretty common in earlier years to clean up with solvents such as paint thinner. This is very effective, but it’s also one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, leads to liver damage and can be carcinogenic, and is also highly flammable. Wash with soap and water if you get some on your hands. Save the thinner for cleaning overspray…get one of the citrus-based non-toxic hand cleaners for cleaning skin.

Odds & Ends

Mercury: This has come up a couple of times in the forum, so it may be worth mentioning. Position-sensitive switches, such as those found in thermostats, often contain mercury, a poisonous liquid metal. If the glass switch vial breaks, the small quantity of mercury inside can get loose and be tracked everywhere. The substance is toxic if ingested, and will release poisonous fumes if heated. If a spill happens to you, do not touch the mercury! It can be scooped up with a couple of pieces of cardboard or a dustpan and disposed of properly. Don’t casually discard this substance! Be sure not to touch your mouth before you are able to thoroughly wash up! Here is a link to disposal and other mercury-related information: http://www.epa.gov/epaoswer/hazwaste/mercury/faq/spills.htm

PCB dust: When working with printed circuit board material, it may be necessary to cut it to shape. There are many ways to do this (hack saw, Dremel, score-and-snap…), but in all cases one should try to create as little dust as possible during the process. This dust can cause health problems – therefore, a N95 (or better) rated paper-style dust mask should be worn to minimize exposure. And the usual caveat of proper ventilation applies.

The other PCBs – Polychlorinated Biphenyls: PCBs are a highly toxic chemical once used as transformer oil and capacitor dielectric before the dangers associated with them were known. Today, these chemicals are outlawed. There is a very small – some might say negligable – risk that you may one day encounter PCBs in old equipment. Be aware that they are out there lurking in some old components. Washing up thoroughly after handling parts and avoiding gel or oil-like stuff you might encounter can help keep you safe.

Metal ‘dust’ – When drilling holes in an enclosure, watch out for the shavings. If the particles are just the right size, they could get airborne and be inhaled. A much greater risk is that they’ll be forced into the skin of your fingers and cause discomfort or even splinters, especially if the holes you’ve drilled are rough. Clean them up when you’re done so they don’t spread around your work surface and get into things!

Safe cooking - A lot of people talk about ‘cooking’ their enclosures once they’ve been painted, to bake the finish on and make it cure faster. Opinions vary on the times and temperatures that this operation should use….200F for 20-30 mins. seems to be the norm. Two strong issues arise if you try this at home. Baking an enclosure can present a respectable fire and/or burn hazard! And the fumes released by the process are definitely of a toxic nature. So, ventilate, and do this outdoors! And don’t use an oven that will ever be used for food again – a simple toaster oven dedicated to the purpose can be purchased cheaply.