June 3, 2019 - Robert John Hadfield

Unblown Fuses

Fixing What Doesn't Look Broken


In our studio we have hundreds of pieces of sensitive electronic equipment. Many of these items have moving parts like motors and belts, not to mention the hundreds of mechanisms that that are built with plastic parts and springs. In other words, there is a lot that can break in a business like ours.

Over the years we have spent a lot of money on Technicians who repair and replace parts and generally keep our equipment in good working condition. Based on a couple of decades of experience, I can usually tell whether or not a repair is worth making or if the item just needs to be retired completely. About half the time the problem is nothing more than a broken rubber belt that runs between two gears. The part itself is pennies so making the repair is usually a no-brainer. But in some cases the problem is unclear, and the repair can end up costing more than the actual unit! There is a gamble on those repairs, so I often decide to simply replace the unit completely.

One such situation almost happened this month.

One morning one of our team members reported to me that a particular piece of equipment had stopped working. I went to the workstation and found that the machine wasn’t turning on. I pushed the power button several times with no response. Next I checked to make sure it was plugged in; it was. I scanned the back of the unit to see if it had a fuse that was accessible from the outside, it didn’t. And finally I swapped out power cables just to make sure that wasn’t the culprit, and of course it wasn’t (that one is always a long shot).

So I pulled the unit out of commission and replaced it with a back up unit.

When something won’t turn on, it’s usually one of two things; a burned fuse or a bad power supply. In some cases I can replace the power supply myself. But tracking down a power supply isn’t easy, unlike belts that have more universal application, power supplies are often engineered for a particular unit. So tracking down a power supply often involves buying an identical unit with a working power supply. And if that unit works, there’s almost no reason to fix the broken unit.

So I immediately got online and started tracking down replacement units. I priced a number of them out and found a few that would work in our studio. But before I hit the “buy” button I had to check one more thing.

Most professional audio and video equipment has a fuse somewhere in the unit. Often it’s accessible from the outside, but not always. So I decided to just have a quick inside the unit.

I removed the rack ears and then the outer case and sure enough, there was a fuse mounted on the power supply. A fuse serves the simple purpose of protecting the equipment. If something is wrong with the electrical current coming into the unit, the fuse burns before there is any damage to the sensitive electronics. Most standard fuses only cost a few cents, but they are there to protect units that cost thousands of dollars.
It’s normally pretty east to tell if a fuse is burned. Most standard fuses are simply a vaccuum cylinder of glass capped off with metal on both sides and a thin piece of wire running from one end to the other. Because it’s made of glass, you can actually see where the fuse is broken. Sometimes you can actually see brown residue on the inside of the glass where something clearly sparked and burned. But when checking a fuse, you are mainly looking for a break in the wire. If you see that break, you know the fuse is the problem.

Unfortunately, when I removed this fuse, I couldn’t see a break. I studied it for several minutes hoping to notice something, but nothing.

So I went back to my computer to continue the decision process.

But before I pressed “buy” I decided to try one more thing. It’s pretty rare, but sometimes a fuse is broken on one of the ends just out of sight. So I decided to run to Home Depot and buy a replacement fuse. It seemed worth the time and minimal investment just to be sure before investing in another unit.

I bought the fuse, placed it in the unit and crossed my fingers. And amazingly, it turned on!

Sometimes fuses just go bad for no apparent reason, and sometimes they go bad protecting the equipment from something that would have otherwise destroyed it. It’s not always clear what caused the problem. And on occasion, as in this case, you can’t clearly see that the fuse was even broken.

The unit has been back in commission for several weeks now and is running strong. There doesn’t appear to have been any ongoing external problem that would have caused it to blow, it is likely the fuse just went bad from time.

Although this fuse took a tape player out of commission and caused a headache for a couple of days, you would never want to be without a fuse. You could actually jump the fuse by placing a wire in the unit where the fuse normally goes, then you would never have to worry about a fuse blowing. Even though that would provide a sense of stability, that would put the entire unit in danger.

There is an obvious life lesson here. Sometimes small and seemingly insignificant things make all the difference. But in this case there is something different I that jumped out at me. It was the fact that something was broken, but it didn’t look like it.

Having worked in professional audio and video my entire adult life I have seen many blown fuses. The burn mark and the severed wire are common visuals. But the most problematic break is the one that you can’t tell is broken. I might have tried to replace an entire unit because the fuse didn’t appear to be blown.

This is a common issue in the human condition, we think something is fine when it’s actually broken. So we try fixing everything around it while we overlook the actual issue. Whether it’s a personal or business relationship, we tend to overcomplicate things that are truly simple. Sometimes the solution is so simple that we don’t consider it. Especially when it doesn’t even appear broken from the outside.

Take a moment to consider a troubled relationship in your life, whether it’s a relative, a romantic partner, a business associate or something else. Is there something small you have overlooked. Before you start considering all of the hundreds of complicated possibilities of why it won’t “power on,” consider the simple thing that may have been overlooked long ago. The simplest solution is often the right one.


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