I've been diversifying my electrical repair skills, away from arcade applications to other things.
Last few days have been all about fans - the kind that you turn on on a hot day.
We have many fans at our place, which is in a tropical, humid area. In addition to a few ceiling fans, we have maybe 8 pedestal fans in regular use (across 3 houses and work/play areas), with some of them operating most of the day and night.
These fans obviously take a lot or wear and, over years of use, start to have troubles. They become slow to start, or don't start at all.
Mostly when a fan starts getting tired I will put a small amount of fine machine oil (like you might use on a sewing machine or a hair clippers) into the spindle, and work that in to get things turning again.
Sometimes I need to change the "run" and/or "start" capacitors (little box-shaped guys at the back of the fan). These caps are typically 0.5uF to 5uF. Smaller fans may only have one cap, some larger fans may have two. In the pic below, you can see how they are often connected using wire nuts. This makes changing them easy.
![](http://forum.arcadecontrols.com/index.php?PHPSESSID=gcd2dhhjc5ve4urs7qtpk5p4an&action=dlattach;topic=164992.0;attach=392184;image)
However, sometimes the fans are just DEAD, and no amount of oil or new caps will change that. I had three dead fans like this in my shed.
I've now learned that these fans all had the same problem: there is a
thermal fuse (2A, 130 degrees) buried inside the housing, inside the coil wiring, that blows. This is OK because it is mostly better to have a dead fan than a fire in your house.
Here is a pic of the coil exposed.
![](http://forum.arcadecontrols.com/index.php?PHPSESSID=gcd2dhhjc5ve4urs7qtpk5p4an&action=dlattach;topic=164992.0;attach=392185;image)
Running a fan with no lubrication or with worn out caps probably contributes to the heat and the fuse blowing, but I suspect these fuses just blow after a few years of use anyway. More on that later.
Today I fixed all three fans by replacing this fuse (also a little oil, and one capacitor).
After I've carefully cut away the string/cable ties and pulled the wires out a bit, you can see the fuse. In this pic I can already tell it is blown (red at bottom, carbon scoring).
![](http://forum.arcadecontrols.com/index.php?PHPSESSID=gcd2dhhjc5ve4urs7qtpk5p4an&action=dlattach;topic=164992.0;attach=392186;image)
As it turns out, there are at least two tricks involved with replacing these suckers.
First trick is you have to be really really careful, because the fuses are actually wired into the coil itself. The coil consists of superfine copper wire with enamel insulation. You don't want to cut or break or pull hard on this, because then it will be a bugger to repair.
You will need to cut away some string or cable ties to access the fuse, so you have to be very careful and take your time. You don't want to damage the copper wires!
Second trick is that soldering a new thermal fuse in is not simple. The fuse is rated to blow at 130 degrees, and most people solder at about 350 degrees! I screwed this up the first time because I forgot
![Smiley :)](http://newforum.arcadecontrols.com/Smileys/default/smiley.gif)
So, two parts. First is to use a lower temperature for your soldering iron. I used 250 degrees. But obviously this is still well above 130.
So, it needs a heat drain or sink as well, to keep the soldering heat away from the fuse. I used my CRT anode discharge cable for this, a bit of ground wire about 1m long with alligator clips on each end. Attached one clip near the fuse, and another clip near the soldering action.
Check out the discolouration (from excess heat) on the thermal insulation!
![](http://forum.arcadecontrols.com/index.php?PHPSESSID=gcd2dhhjc5ve4urs7qtpk5p4an&action=dlattach;topic=164992.0;attach=392187;image)
Once you are done soldering, test that the fuse is still good with meter. Also good idea to check that the coil is still good (multimeter/ohms across the AC plug pins, there should be connectivity with some significant resistance).
I'm going to leave you with this pic of three thermal fuses I replaced today, with a good fuse for comparison. The fuse on the left is good/new, and you can see it has a healthy clear/pinkish colour underneath. The two on the right are completely blown, and the colour beneath is quite orange/red. Far right is from the fan pictured above, which is a little larger and clearly got quite hot.
![](http://forum.arcadecontrols.com/index.php?PHPSESSID=gcd2dhhjc5ve4urs7qtpk5p4an&action=dlattach;topic=164992.0;attach=392188;image)
The fuse 2nd from left is the most interesting. This is because it is only partly blown, on the way out. There is definitely some red built up around the leads, but looks mostly OK. This fuse tested bad at first, then tested good again when I jiggled it a bit. I replaced it anyway, fan is happy again
![Cheesy :D](http://newforum.arcadecontrols.com/Smileys/default/cheesy.gif)
Hope this helps some people save their fans from landfill
![Cheesy :D](http://newforum.arcadecontrols.com/Smileys/default/cheesy.gif)