n2585722

While I was at MACNA my system ran OK with one exception. One of my sump cooling fans went out and took out the fan controller with it. All the fans were off because of this with the exception of the cooling fans for the LED lighting. The water temp did go up to 82 degrees with the fans out. This was not so bad. The real issue is it could have caused a fire since the the circuit board in the fan and the one in the controller had burnt spots. You could smell that burning smell in the room a couple of days after the fan and controller were removed. I disassembled the fan and controller. The first photo is of the burnt parts of the fan and the controller. It could have been worse. I decided I need to find a better way instead of using the cooling fans I had in the system. This write up is on what I did to hopefully get a longer life from the fans and hopefully prevent them from burning up when they do go bad.

First I checked out the available 8cm fans locally. I found two that had removable blades for cleaning. So I decided to give them a try. I purchased 2 of each. Along with them I got a replacement for the fan controller, 1 package of 2.2ohm 1/8 watt flameproof resistors and some 1/16" heat shrink at our local Fry's. So it was just a matter of taking the fans apart and making them more water resistant and adding a flameproof resistor in the power wire of each fan.

I added the resistor to the center wire of the fans first. This is for protection in case there is an extreme over current event the resistor will open. Hopefully being flameproof it will have less chance of causing a fire than no protection at all. First I cut out about a 3/8 inch section of the wire about 1 1/2" away from the connector. (see photo 2). I then trimed off a small amount of insulation from both sides (see photo 3). I then tinned the wires with solder. Also in the photo are the resistor and a piece 1/16" heat shrink. I placed the heat shrink on the center wire far enough away to make sure it is not heated in the proces of soldering the resistor to the wire (see photo 4). I cut the wire on one end of the resistor to 1/4". I then tinned the resistor end that was just cut. I then soldered the wire to the cut end of the resistor. After that i cut the other end of the resistor to match the length of the center wire and resistor to the other wires. I then soldered the open end of the resistor to the remaining wire end (see photo 5). After the joint cooled I slipped the heat shrink over the resistor. I then heated the heat shrink to shrink it over the connection(see last photo).

After installing the resistor I proceeded to try and make the fan more water resistant. First I removed the fan blade assembly by pressing it off from the motor mount side(see photo 6). After getting the blade assembly off I plugged the bearing with a piece of paper towel to make sure nothing gets in the bearing while working on the fan (see photo 7). I added aquarium sealant (RTV) between the motor case and the motor PC board assembly. The fan has a speed select switch. I tried it in all three positions and decided on the fast speed position. I also put RTV on the switch. The RTV was also added around the power cable both sides. The old fan as far as I can tell had salt build up on the cable all the way to the PC board. This attracted mosture which caused the meltdown. After the RTV set I sprayed on a thin rubber coating around the motor stator PC board assembly(see photos 8 & 9). This doesn't look the best but if it works it will be worth it. After everything dried I reinstalled the blade assembly and checked the operation. I cannot tell any difference in the fan performance after doing this. All seems to work correctly. The fan is shown in the last photo after everthing was completed.

Parts Used:
2ea UC-8EB fan by Enermax
2ea UCMAA8A fan by Enermax
4ea 2.2 ohm 1/8 watt flameproof resistor
4ea 1.5" 1/16" heat shrink tubing
1ea tube of silicone RTV (aquarium safe)

I used the 2 UCMAA8A fans for sump cooling. These are the ones with the switches and have the maximum flow rate of the fans. I plan to use the remaning 2 fans for exhaust in the back cover. At this time I only have one of the sump cooling fans connected to power. I am testing whether it will handle the job on it's own before powering both fans. That way I am good to go if I loose one fan. I also removed the two sump cooling fans from the fan controller. I figured that it was OK to have them running at full speed and use the controller to turm them on and off as needed. They seemed quite even on the high speed. The original reason for the controller was I was going through the small fans in the electronics compartment very fast. This way I can turn them down to a lower speed and they hopefully will last a lot longer. If these fans last longer than 3 months they have the others beat. I had the first failure in a month and the second in 3 months with the old fans. I guess it will be a few months before I know if this will help. I will make comments if I have any issues.