Colorless writings, part 20 – Repair statistics

At first, i’d like to say WoHOO! It’s been about 18 moths, and there are now exactly 200 different pedals covered and i’ve also posted 20 of these unintelligible texts about preferences and gut feels.

Anyway. Back to business.

 So we’re talking about repairs?

Yes. Can’t exactly recall when i did my very first pedal repair. But since i’ve been heavily addicted to effects and sounds for something like five years now, the first one must have been around that time. About five years ago. Of course, the circuit debugging skills are something quite different today than what they were back in those days when i was starting out. I still do feel uncomfortable working with massive SMD boards, but to date, i’ve been able to fix every single one i’ve come across with through hole components. One exception being an old japanese Boss DD-3 which had a fried chip. Two pedals that i’ve given up have both been Dunlop manufactured modern “MXR”s.  I do find it to give more of a mental boost to figure out what’s wrong with someone else’s pedal than a pedal of my own. Sure, i’ve bought tens and tens of broken/defect units for myself and fixed them. But still. There is this certain excitement when poking around unit that isn’t mine. After all, i don’t mind throwing something that i own to the trash bin, but that isn’t an option when doing the fix for someone else. Think of it as tattooing. When you tattoo yourself it doesn’t matter all that much, but when you’re tattooing someone else, the results do count..

What is the most common fault with a pedal?

This is very common question i get asked. Almost as common as “how long it takes to build a pedal”. Answer to both questions is simply, “it depends”. Sadly, i haven’t kept a log of all the repairs i’ve done, so i have to rely on my recollection. (I should start to keep a log though, so we can revisit this writing in five to ten years..) Bosses and Ibanezes. For these brands, the most usual situation is that somebody has been trying to use the unit with a wrong polarity power supply. This results in burned (or in extreme cases, exploded) parallel polarity protection. Most cases are easy to fix, but some i’ve seen have had the board burned to the degree that the fix has not been as simple. Bosses are built to pretty high degree of excellence, and other than burning the power supply section, there are not that many common faults. Occasional worn out switch would come to mind, but that’s it. If Bosses are used in civilized manner, they will last years and years of physical (ab)use. This same thing applies with Ibanez boxes. Although, there are noticeable amount of more broken footswitches on those units. Still, the switches and burned polarity protection. Those are the main faults. For more boutique-like pedals, the faults are the same. If there is a parallel polarity protection in place, i’d say it’s pretty likely someone burns it with a wrong power supply. My rough estimate for probability would be around 60% chance of someone being idiot enough not to understand the difference between AC and DC power. I’d still place this “burning polarity protection” as second on my list of common faults.

All the switches, regardless of type, will simply worn out with use. It doesn’t seem to matter if the switch is made by high end brand or it is the modern chinese, cheapest possible part. For example, all the faults within Vox brand pedals i’ve seen so far have been with the mechanical switches. And those switches are the higher end industry standard, mexican Carling brand switches. Same thing with Wampler, Menatone and tons of other higher end pedals. Most common issues with those are the switches. And those usually can take up to several years of active stomping before giving up on you.

Switches first, killed polarity protection second, what then?

Those would be the most common faults. After the user fault of killing the polarity protection, the next common fault would be the burned out semiconductor. I’ve seen burned opamps, hex inverters, CMOS switches, transistors, you name it. The easiest way to kill a semiconductor in a pedal is to burn the polarity protection out first and still not believe that there is anything wrong with the power supply used. Feed the board with a short circuited power for long enough and if we’re unusually unlucky, we’ll have damage to the semiconductors as well. Some designs do not protect the CMOS switching and other sensitive components well enough. Those pedals are bound to end up on my desk more often. Still more rare occasion than killing a switch, but still. Noticeable fault in number of fixed units. Burned diodes, opamps, DC-DC converters.. Yup. I see those every now and then.

What’s funny, i’ve grown to hear a few different faults in effects. Certain type of gating and behaviour has always been due to a broken diode in a signal path. That’s something i’m actually rather proud of..

Burned out semiconductors third. Anything else?

I’ve seen a few instances with dead and/or leaky electrolytic capacitor causing the circuit not work. This can happen, but it is much more unlikely than all the other above. Key idea with all the capacitors would be that if it’s physically broken, then it’s broken electronically too. It’s very rare occasion to see any polyester or ceramic capacitor broken. Electrolytics can be killed simply by reversing the polarity inside the circuit or for a single cap. Tantalums are a thing of their own. I’ve heard stories of these to short out, but i’ve rarely seen that myself. Well. I wouldn’t use a tantalum power supply circuits anyway (they are great for signal paths though).

In all. That’s pretty much it. After all, we’re talking about very simple amplification and filtering circuits in all pedals. There basically only a handful of different components in use. And since there is only a few ways to hook up a semiconductor to have it working, the circuits in every effect pedal have similarities. Fixing a pedal is pretty much like fixing a car. Only with smaller parts. Some parts are brand and model specific, but most are interchangeable between every pedal. I don’t know how to fix a car and i have no plans to learn it. I do, however, have a mechanic to do that for me. This comparison is more true than most of us would like to admit. I recently had a broken tail light glass on my car. I changed it myself, but the procedure was pretty close to changing a broken pot knob on a pedal. I also recently had the water pump and engine sealing renewed, which would be a lot more like changing a CD4066 switch and a quad opamp on a pedal. The latter i can do. The former.. I’d rather leave it to the people who really know what they are doing.

In light of the last few sentences, i’d like to point out that you don’t have to repair your pedal yourself if you do not know what you are doing. In that case, please don’t even try. You’re bound to do more harm than good. You most likely know someone who’s been working with soldering iron for years. Ask him to do the repairs. Or send it over to me…

 

EDIT!!! Nope. As of this date, 7th of october 2017, i’m saying the text above is full of shit. Dead cap is way more likely to cause issues than a burnt semiconductor. This edit should suffice..

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