Computer fan noise and maintenance

[espresso]

Re: Computer fan noise and maintenance

That pot would have to be powerfull. I use 1W resistors in series with fans to reduce rpm/noise. For 12V/150mA fans the appropriate values would be between 47-100 Ω in my experience. For 400mA you would have to go with even lower values (probably 22-47 Ω).
You should try 100Ω pot (rated at 1.5W at least).

[JonathanAnon]

Re: Computer fan noise and maintenance

I have a problem with a computer whose fan stays on 100% of the time, and drives the user mad. I've checked the normal things, cleaned the case etc etc and no dice. I've read that this can happen when the transistor controlling the fan shorts.

It's a 12v 400mA fan, so I was thinking that if solder a 1K linear pot in series with the fan, I could adjust the fan to where it was capable of doing it's job, without driving the user to the insane asylum.

[lti]

Re: Computer fan noise and maintenance

Why was an 80mm fan in a 1U server?

I have used 20W motor oil in fans. It seems similar to the oil used in sleeve bearing fans. If you use enough (not just a drop), it will actually last a while.

[c_hegge]

Re: Computer fan noise and maintenance

^
I saw that in a HP I came across last week. The PSU was replaced with a really cheap and nasty $20 unit, and its fan was failing. When I opened the case, I was horrified to find a chain of molex connectors which were touching the CPU fan. I replaced the PSU with a recapped Hipro 300W. Nedless to say, I zip tied the wires up good.

[kaboom]

Re: Computer fan noise and maintenance

When the previous tech put together the server, he obviously didn't pay enough attention because some wires were stopping an 80mm sleeve bearing intake fan from spinning.

What else is new? So-called computer "techs" still don't tie their wires up?

[Pentium4]

Re: Computer fan noise and maintenance

Just this last week, we had a 1U server with a failed hard drive so it came in for maintenance. When the previous tech put together the server, he obviously didn't pay enough attention because some wires were stopping an 80mm sleeve bearing intake fan from spinning. This was about two years ago. I yanked the fan because it took some force to move the blades. I figured that the motor fried..I plugged it in and it gave a little twitch and wouldn't budge even with me giving it a pushing start. I put in a drop of Tri-Flow and manually spun it for a while, then let it sit face down over the weekend. I spun it manually a little while and it felt much more smooth. I plugged it in and it still works! Goes full speed no problem and it's fairly quiet. Had to share my little story because I'm surprised it still works...It's some chinese brand I've never heard of, I'm not even sure what the first letter is, maybe an e or a c

[c_hegge]

Re: Computer fan noise and maintenance

What I've been using lately is Chainsaw lubricant. It's thick enough not to evaporate or leak out of the bearings, but it's not too thick like the stock grease.

[espresso]

Re: Computer fan noise and maintenance

That Mobil 1 could be similar to my "High temperature grease" on the picture. Both are lithium complex grease types. Except that Mobil 1 has a higher viscosity which you compensate by mixing with oil.
I actually do this by disassembling the fans and then cleaning the bearings and the shaft with a degreaser spray. Only then I apply grease along the entire length of the sleeve. I usually use a toothpick for this.

For worn out bearings I use higher viscosity grease (800cSt). I still haven't been able to see the final results in terms of longevity. I know that the cheapest fans I have failed within several months of use with stock lubricant. Now they've been spinning on grease for over a year.

[999999999]

Re: Computer fan noise and maintenance

^ I use oil or oil-grease mix that has a drop point just below the anticipated ambient temperature the fan sees, so it isn't just a film of grease but rather I pack the opening practically full and seal it with the plug.

As the fan spins the thrust washer continually adds lubrication if there are any voids, unless the washer became deformed when it was removed in which case I consider lubing it only a temporary solution to keep a fan running a few weeks or less till it is replaced.

My preferred lube hasn't changed much over 5 years since my last post in this topic. It's Mobile 1 synthetic grease http://www.mobiloil.com/USA-English/...ic_Grease.aspx mixed with Mobile 1 5W20 or 5W30 oil (whichever the store I happen to frequent carries, the 5W20 still seems rarer around here).

If you mix up a batch it will separate some over time (years), but in a fan bearing way the rotation keeps it mixed up. I'm not suggesting this is the best possible lube that a NASA mission could ever hope to find, but rather it serves my purposes and I came upon it using grease and oil I was already using for vehicle and equipment lubrication so it's handy not to have to buy or store something else. A tube of that grease will lube everything you own for many, many years and a nice side benefit is that unlike the old black moly dino-based grease tubes, the Mobile 1 synthetic won't separate and leak oil out of the grease gun while in storage which used to cause me to have to wrap the gun in newspaper and put it in a plastic bag when it had dino grease in it.

[espresso]

Re: Computer fan noise and maintenance

I've been doing some research on lubrication and came to the same conclusions as 999999999 posted a while ago. I used all kinds of greases on pc fans just for fun. The longevity seems to be better than with stock lubricant.
I'm just not sure how long can a fan run on a thin film of grease that doesn't get replenished.

There is also some difference in rpm when using grease instead of oil. It can be as high as 20-30% when the fan starts. But after 15 minutes or so, the speed settles closer to the oil's maximum speed. Usually grease lubricated fans still have 3-7% lower rpm than oil lubricated fans. This is for 8cm case fans and grease that has viscosity 100-150cSt. That's a viscosity grade of a typical multipurpose lithium grease.

And the only non automotive oil that I found thick enough for the job is Power Lube. It's an industrial grade oil with addition of PTFE that should help fill microscopic asperities on the bearing surface and hence reduce startup friction and avoid boundary lubrication in general. It is my understanding that PTFE acts as a kind of fine deposit that settles on tiny imperfections on the surface.
These are some of greases that I used

[rxtxau4]

Re: Computer fan noise and maintenance

WD40 will also swell some plastics. The military banned it from use with some electrical connectors because of causing the soft insulators to swell stopping the connectors seating properly & destroying waterproofing.

[linuxguru]

Re: Computer fan noise and maintenance

A reputable ball-bearing fan as a replacement fan is almost always worthwhile - but if you don't have one handy, it's possible to squeeze out a few extra months out of even a seized sleeve-bearing fan with a drop of oil. It's hard to beat the economics of premptive lubrication.

[PCBONEZ]

Re: Computer fan noise and maintenance

Mare Island <<-- I lived in Vallejo for around 12 years.
... Or I had a house there. I was never home...

[bgavin]

Re: Computer fan noise and maintenance

WD80 is also a rust promoter. I made the mistake of using it on some of the chrome parts on my '76 hawg when I put it away for the winter. They got badly rusted.

My neighbor was working at the Mare Island submarine yards at the time, and told me about the rust thing. He cut open an empty can of WD40 with a hack saw, and showed me how rusted the can was on the inside.

As to all this fan maintenance, is there a valid reason for undertaking all this work instead of replacing the fan? I can see it, for hard to find fans such as those found on video cards. But case and cpu fans... ?

[PCBONEZ]

Re: Computer fan noise and maintenance

I agree that WD40 is not a lubricant.
It's a solvent and a water displacer.
It's ~80% Kerosene, ~10% tallow oil, and ~10% light oil.
[~ means ball park I didn't look it up.]

The Kerosene is there as a solvent and to displace water.
The oils are intended as a temporary barrier against moisture and are too light to much of a lubricant.

If you are soaking whole fans in it then you are getting oil and kerosene into the windings of the motor and that's probably not a real bright idea.

.

[999999999]

Re: Computer fan noise and maintenance

WD40 is not a lubricant it is a water displacer. I can't say how worn down the fans are at this point but if they had been, maybe if they still are lubed with a very thick oil they should not need relubed every few months. Sometimes the bearing plug on a fan does not seal good and an extra measure is necessary, to put a coated sticker over it to make an air-tight seal. All oil must be thoroughly wiped off the hub to make sure the sticker adheres well.

[Langly]

Re: Computer fan noise and maintenance

Ive just soaked my noisey ones in wd-40 sometimes washing them first, then used a old AT powersupply to run them and get rid of the excess oil. the odd fan in my firewall which I cant find a replacement for needs that every few months.

[bgavin]

Re: Computer fan noise and maintenance

Thanks for the Noctua tip. My vendor tells me that Panaflos are going away. Pity... they work so well for me.

[davmax]

Re: Computer fan noise and maintenance

Talking of quiet fans. Noctua make some beauties, low fan noise down to 8db(A) for 59 cu metres/hour (120mm fan), oil pressure bearings and >150,000 hour life.

[PCBONEZ]

Re: Computer fan noise and maintenance

The 12v to the HDD powers the motor only and they are regulated.
The electronics are on 5v and can't be affected by 12v line fan noise.

Besides the fan, anything on 12v (including add-in cards) is going to have it's own local VR and that's where the filters are. There is no need for another at the fan.