Lydian's FastMHz

Autie retro tech geek!

Replacing a Power Supply Fan

There may come a time when you wish to replace your PSU fan with a quieter Panaflo model, or your old one just bites the dust. Most PSU fans are 80mm standard case fans. You can use a metric ruler to be sure you are getting a new one that will fit. The voltage must be 12v DC. You can not install an AC or other voltage fan into your PSU. What follows is a tutorial on how a standard PSU fan would be replaced with another.

A standard power supply that would be found in most modern PCs. This is our test subject for the following tutorial.

A first look inside. This one has been well used, and their is an abundance of dust inside. This is also a good time to clean your PSU if it has a lot of dirt inside. The fan in this PSU has given in, and will be replaced with a new one.

The first thing you want to do is to unscrew the fan. On the back of the PSU where the air comes out should be four screws which hold the fan in.

After unscrewing the fan, its time to remove any wire ties that may be holding the wires. Most PSUs will have at least one. Simply clip it with wire cutters, and carefully avoid cutting the wires just yet.

After clipping the fan free, look for its connector on the circuit board. It will generally look something like this. If your PSU’s fan is soldiered directly onto the board, its probably time for a whole new unit. Only cheap low quality ones generally are soldiered directly, and its not worth the effort to desolder it from the circuit board.

Now that the fan is completely uninstalled, its time to remove the connector to be recycled. Clip it about midway through. If your fan is seized up, go ahead and clip it right at the fan, otherwise, clipping it midway allows the fan to be used for something else if you wish.

Now, this is extremely important. The colors MUST be matched up. Make sure the red wires match, and the black/blue wires match up. Soldiering it backwards will either not run the fan causing the PSU to fry from overheating, or the fan itself will fry. The red is the positive lead, and the black/blue is the negative lead.

You will need a soldering iron and solder. Extremely helpful is some soldiering flux and a vice. For professionalism, pick up some heat shrink tubing. Otherwise, you’ll need some electrical tape.

The next thing to do is to tin the wires. To do this, apply a small amount of soldering flux. This helps the soldier to stick to the wires. If you don’t have a vice (I got the one above from Radio Shack for $5), you may need somebody else to lend a hand.

After all the wires are tined, slip pieces of heat sink tubing over two of the wires, either on the connector or the fan. If you don’t have heat shrink tubing, skip this step.

Next, soldier the wires together. Then slip the heat shrink tubing over the solder connections, and heat the tubing with the soldiering iron. Do not apply the tip directly to the tubing or it may melt. Simply hold it under it and the tubing will shrink to protect the bare wires.

If you didn’t have heat shrink tubing, wrap electrical tape around each individual wire, and then wrap a third strip around both. This will ensure that nothing will short out.

Now that the connector is on the new fan, its time to reinstall it. Place the fan in the spot you took the old one from, and reconnect the connector to the circuit board.

Screw the fan back in, and screw the cover back onto the PSU. When you place it back in your system, observe the fan right after you turn it on to make sure it spins up. If it doesn’t, immediately shutdown and backtrack to check your soldiering connections, and that the polarity (red – red, black/blue – black/blue) is correct. You may also have a dead fan. Test your fan on a nine volt battery to see if it is any good.

That’s it! Nice and simple procedure. Be aware that this voids the warranty on your PSU, so if its brand new and the fan died, try to RMA it first.

I recommend a 24 CFM 80mm Panaflo for PSU fan replacements.