Case fan problem: fried 1 mobo and 2 fans so far. Need help!

G

Geolith

Limp Gawd
Joined
Apr 7, 2012
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311
For starters, I've been assembling my own rigs since 1997, so I'm not exactly a rookie in this. On the other hand, I've never actually modded any case before, so this is a new territory for me, and it shows, apparently.

Now the problem. Recently I bought CM Storm Scout. Very nice case, I really like it. But it comes with red LED fans, which I don't find suitable for my blue LED dominated environment. So I decided to swap the red LED fans for blue LED ones. And that's when the problems started.

If you don't know, this case has the option to turn off the LEDs -- of course, if the fans are provided with on/off switch cable. I ordered two such fans from Cooler Master (front 140mm and rear 120mm), but the on/off cable connectors on them differ from the ones the case has, so they can't be connected as they come. I retorted to some soldering and stuff, but, apparently, I was doing something wrong. I had trouble in making the case switch turn on the LEDs, I experimented with different ways of connecting, etc.

At some point, The front fan cables started smoking. I'm still not sure what happened. The fan became useless, so I ordered another one.

This time everything seemed fine, the fans working without problems. Then, yesterday morning, I noticed that the new front fan wasn't rotating. I unplugged the power cable from the mobo CHA_FAN connector and plugged it into a different CHA_FAN connector, near to where RAM chips are located. When I started the PC, I felt a burning plastic smell roughly from that connector area, accompanied by BIOS beeps. I immediately turned off the system and disconnected all the fans.

After that, the mobo stopped recognizing any RAM. The BIOS gives the beeps standing for "no memory detected" and that's it. The memory chips are OK, of course -- they work on another PC with no problem. I tried entirely different chips, too. All the same. So it can be safely said that the mobo is a toast.

Since I had nothing to loose, I decided to get into the problem with the front fan. I connected it directly to the PSU's molex connector. It started working. Then I connected the on/off switch cable. And the cable started smoking heavily. There goes the second brand-new case fan.

Now I have ordered a new motherboard, but I'm not sure what to make of this situation. What the hell is happening? What am I doing wrong? I'm connecting everything exactly the way the stock fans were connected, or I think so. Please give me some advice, I don't want to fry another motherboard. They are ASUS P8Z77-V Pro and they don't come cheap.
 
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Um. Stop whatever you're doing. It's obvious you're in unfamiliar territory with dc current and you're going to keep breaking stuff. Leave the led fans out and rock some normal fans.
 
djgizmo said:
Leave the led fans out and rock some normal fans.
Click to expand...

Well, I could just put the stock fans back and simply leave the leds off. Or find the replacement leds with suitable connectors, so that I don't have to solder (and fry) things. :D
 
OniFactor said:
...i think he means more like, make sure you didn't FUBAR it connecting your frankenstein'ed fan..
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Oh, I see. :D

Speaking of frankensteining... Actually, all I did with the fan is replacing the connector with a compatible one. Hardly a rocket science, considering there are only two wires. If I even short those wires, all it does is simply turning the LED on. :) I don't think the problem is in the replaced connector or the way it's crimped or soldered. I'm missing something entirely else here.

I really hoped this thread would give me something more than "don't fry anything else, dude".
 
I think a better (and, most importantly, safer) solution would be putting back the original fans, only with replaced leds. I'm fairly good at swapping leds, tried before several times and never burned anything so far. This way I could get my blue leds, and keep the mobo alive in the process.
 
can you give us more information as to how exactly these were modified? i'm not understanding how a fan could have an on/off switch that controls the LEDs on the header, that doesn't also control the fan, with only 2 wires..
 
It honestly sounds to me like you somehow fubard your soldering. Where did you solder the connections? Provide us pictures of everything involved.. words only leave the facts to our imaginations.
 
Oh and one more thing, even though is a simple switch with only 2 wires completing a circuit, there is a + and a - to an LED... if you are all of a sudden competing a ground circuit to a 3v + circuit (most LEDs in fans are 3v) you can be causing issues there. Usually the LEDs will just pop and nothing bad will happen, but sometimes in very rare instances (ive seen this happen with other electronics) the LED an melt in such a way that it actually fuses the circuit closed causing what happened to you.
 
That's a lot of replies. Thanks everyone!

I think I finally got to the root of the problem, or I think so.

Thing is, the switch on the case is not passive, but powered, meaning it doesn't simply short the LED wires to turn them on, but also powers them. In other words, the case switch is able to turn on the LEDs even if the fan is disconnected from power.

I think that may be the reason behind the problem. You see, the replacement fans don't need extra power to turn on their LEDs, they have three wires, one of them apparently powering the LEDs (in contrast, the stock fans have only two wires, plus two separate wires for the LED switch). In short, I was giving the power to already powered LEDs, or something like that. But of course I may be wrong.

Anyway, I swapped all the red LEDs with blue ones on both stock fans and installed them back. Everything works, turns on and off, etc. Problem solved, but still it would be great to have a full picture of what happened, just for future. I will post all the necessary photos in a couple of days and I would greatly appreciate your further input.
 
JLangevin said:
Usually the LEDs will just pop and nothing bad will happen, but sometimes in very rare instances (ive seen this happen with other electronics) the LED an melt in such a way that it actually fuses the circuit closed causing what happened to you.
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In my case the LEDs remained perfectly intact, it's the cables that melted. I was even able to reuse those LEDs on other fans.
 
You see, the replacement fans don't need extra power to turn on their LEDs, they have three wires, one of them apparently powering the LEDs (in contrast, the stock fans have only two wires, plus two separate wires for the LED switch). In short, I was giving the power to already powered LEDs, or something like that. But of course I may be wrong.
Click to expand...

The three wires going to a fan are +12v (red), ground (black), and tachometer (yellow). If your previous fan had four wires and two powered the fan and the other two powered the LEDs you'd have two red wires and two black wires.
 
FaRKle0079 said:
If your previous fan had four wires and two powered the fan and the other two powered the LEDs you'd have two red wires and two black wires.
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Not exactly.

The first pair of wires is yellow/black and it ends with a female molex connector (a standard 4-pin molex, but only with 2 pins).

The second pair is indeed red/black and it ends with a female 2-pin connector, which connects to the male connector of the case switch.

The replacement coolers had entirely different sort of on/off switch connectors and there was no way of connecting them without modification, and that's where I see the root of the problem -- I think that the new coolers were somehow incompatible with the case switch.
 
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OK, here's the promised photos. I'll try to explain what is what as best as I can.

Below are the stock fan connectors. The female 2-pin connector on the left connects the fan to the on-off switch. The 2-pin molex on the right connects the fan to the PSU.

stockfanconnectors.jpg


Below is the case's on/off connector, which is a male counterpart of the aforementioned 2-pin female connector. It leads to the on/off switch located at the top of the case.

caseonoffconnector.jpg


The case has two on/off connectors, both pictured together below. As you can see, their cables are interconnected.

caseonoffconnectors.jpg


Below is the molex that powers the on/off connectors. It also leads to the on/off switch located at the top of the case.

caseonoffmolex.jpg


Now the replacement fans. Below is the standard 3-pin connector which goes to the chassis fan socket on the mobo.

replacementfanconnector.jpg


Finally, below is the 2-pin on/off connector of the replacement fan.

replacementfanonoffconn.jpg


As you can see, the replacement fan's on/off connector could not be connected to the case's on/off connector out of the box, both being male. That's why I had to replace it with a female connector from a stock fan. Apparently, I made some mistake somewhere in the process, maybe confused the cables, or maybe it simply wasn't compatible with this particular setup of the case connectors.

Just to clarify: whenever I mention "on/off connector", I mean "LED on/off connector", of course.
 
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