replacing fan in power supply, Cooler Master RP-650-PCAR

[jcromano]

Hi,

Last night my pc started making a grinding noise from one of its fans. I shut it down, unplugged it, attempted to drain any residual charge by pressing the power button a couple times, and poked around.

I tried spinning the fans by hand. Most of them spun freely. A case fan was completely stuck in place. It wouldn't spin. I plugged the computer back in, turned it on, and watched the fans. The case fan did not spin at all. The horrible noise was coming from a fan inside the power supply, which was alternating between speeding up and slowing down, almost to the point of stopping.

I disconnected the power to the dead case fan and powered up again. The power supply fan seems to be steady now, and much quieter, but still far from silent. And the noise it was making earlier has me worried that it might be damaged and not doing the job it needs to do.

I am certainly going to replace the dead case fan. I am wondering whether it is easy and worthwhile to replace the fan inside the power supply as well. The PS is a Cooler Master RP-650-PCAR. I'd have to open it up to get inside. It looks like it wouldn't be too hard to get the fan grate off. Does anyone know how hard it would be to swap the fan out after that? Is it even possible to get the right size fan?

If it's a complicated job, I'll probably leave things the way they are and hope for the best. But if it's a simple swap, I'll probably go ahead and try it.

Jim

 

[Zepper]

Unfortunately most PSU fans are thermally controlled internally to the PSU, so they speed up or down based on the temp of the air passing thru the PSU or of one or another component within the PSU. So any new fan should match the specs of the OEM one as closely as possible so the thermal controller will work with it properly. An exact replacement is best, but I've not found it easy to get any kind of parts like that from C-M unless you send it back for warranty repair where they'll most likely send a different one back to you - costs more for shipping than it's worth. So you'll likely have to hunt for one that is the same dimensions (some PSU fans are thinner than the standard 1" (I think a 20mm thick Yate Loon 120mm fan is available at Jab-tech.com.) operates on the same voltage/current and at roughly the same CFM at 12V. Even getting the specs that aren't listed on the fan's label won't be easy from C-M, but sometimes the OEM part number is on the fan as well as C-M's part number, so you may be able to look it up with your fave Web search engine (may even have the OEM's original label on it). Usually the voltage and current or power are marked on the fan label (any two of those specs can get you the third with a simple calculation. Also the connector that hooks the fan to the PSU can be non-standard (IOW, not likely to be found around the house unless you're a techie with several junk boxes full of stuff c'est moi), so when I replace PSU fans, I cut the OEM fan's leads about 3 or 4" from the connector and splice it to the replacement fan's leads so the total length is about the same as original. I've used small wire nuts to splice if I have to, but solder and shrink wrap are best.
. I've done this often as the fan is usually the first thing to go on a PSU while it would have at least several years of life left and it's usually a cheap fix, but then I've been teching it since the late sixties.

.bh.

 

[jcromano]

Thanks, Zepper. That all sounds tricky enough that I think I'll wait for the really bad noise to return before attempting to swap the PS fan. But the info you've provided is very good.

Jim

 

[mindless1]

I don't have that model, but do have the 500 and 600W version. The default fan has a sleeve bearing, you should find that it responds well to being lubed with heavy oil. At least on mine it is a standard 120mm x 25mm (1") thick, though I forget if it had a connector or it's leads are soldered directly to the PCB.

If after lubing the fan you find it is not quiet enough, you don't necessarily need to source the same replacement, actually many people have observed that these fans tend to spin fairly fast, more than they should need to per the rating of the PSU. Thus you should be able to, and would probably want to, select a fan with a current rating roughly 60-70% of the value on the fan's label. If it is replaced I also suggest getting a dual ball bearing fan or a high quality sleeve bearing fan (Panaflo, Papst) not junk like the CM original or a Yate Loon... or else it'll just fail again unless you more frequently relube it.

Given a soldering iron and a couple pieces of the appropriate diameter heatshrink tubing, if worst comes to worst you can just splice and solder the old connector and a portion of it's leads to the new fan wires.

I recommend that you not wait to relube it, once you hear the noise it will be wearing away the bearing slightly, it's much better to preventatively lube it ahead of time. On mine I actually opened and lubed them before I even put them in a system (after first confirming they weren't DOA, otherwise I didn't care much about voiding the warranty by opening it as they were about $10 AR at the time). As far as replacement brands go, several major brands make something that'd be suitable. Best guess is the original fan is about 0.3 to 0.4A, so shoot for about 0.24A replacement.

 

[jcromano]

Thanks a lot. I have tomorrow off and hopefully I can play around a bit then.

Jim

 

[Zepper]

Remember that if you do get a lower current fan, the thermal controller will have roughly proportionally less effect on a lower current fan than it would on a higher current fan. And remember that at least part of the reason your fan has failed already is that the PSU maker (probably at the behest of the bean counters) went with a sleeve bearing fan. Back in the day, no self-respecting PSU maker would put sleeve bearing fans in their PSUs. It was dual ball or nothing. Ball bearing fans can be noisier, but I have some here that are very low noise - but they aren't cheap.

.bh.

 

[mindless1]

I usually pick the fan based on where I'm placing an order for something else at the time, though I mean among brands on my short-list (San-Ace, NMB (aka Minebea-Matsushita), Nidec, Delta, Comair, maybe even a Sunon or Adda considering how little my particular PSU cost AR), which usually means I can find something for $10 or less though without being picky about the connector on it which isn't so bad as the typical case fan connector is less common than a smaller or two-pin type found in PSU "if" it uses a connector at all. I just assume I'll need to get the soldering iron out and then save a few minutes when I don't need to.

I also vaguely recall that some of these may have had a fan grill that was dented or inset too much (not sure exactly, mine didn't have the problem but other people reported it) such that the fan would barely rub against it. If yours was bordering on this state and now does rub, it might just be a matter of popping off the grill and ever so slightly bending the mounting legs down so there's a millimeter or two more clearance. However, this situation was reported with new PSU, since yours hadn't had the problem it seems more likely to be the bearing needing relubed. It might run a long time after relubed (given lube every 9 months it might last the life of the PSU if not worn down too much yet), or at least long enough that you have no rush to get a replacement fan.

 

[jcromano]

What kind of lube should I use? WD40? Something thicker?

Also, does lubing the fan mean opening it up to get at the bearings?

 

[Zepper]

On sleeve bearing fans, access to the bearing is often under the label on the hub. They usually peel off easily, but the application of a little heat from the palm of your hand can help. WD40 is a type of penetrating oil that is quite thin. Most household (3 in 1, etc.) oils are thin. I couldn't be sure what to recommend that would be safe around plastics. Thick oil to me would be automotive motor oil like 30 or 40 weight or 90 weight gear oil but even 20 weight or maybe even straight 10 would be thicker than most household oils - neither of which would be safe on typical plastics. If you can get it into the bearing w/o getting on the plastic, then it might work.
Wipe off any oil you get on the plastic with alcohol and dry well as you'll want the label to stick back in place to help protect the bearing from dust.

.bh.

 

[jcromano]

Update:
I've oiled up the PS fan. I went with sewing machine oil, as recommended by someone somewhere on the internet. I gave the CPU fan a shot of oil, too, and the new case fan is in and running. Things seem quieter than they were this morning.

Getting the PS fan out turned out to be a little more work than I'd hoped for. Had to take off the CPU cooler and unplug half the case to get the PS in a position to remove the fan. But it's all back together now and apparently running smoothly.

Thanks to everyone who contributed advice. You were very helpful.

Jim

 

[mindless1]

Anything is better than nothing, but as Zepper pointed out WD-40 is just a penetrant and water displacer. The types of plastics used in fans aren't particularly vunerable to oil (keeping in mind, they put oil in it in the first place and it gets on the plastic in the bearing chamber) and aren't subject to high stress anyway.

Whatever you have is a good start for now, but ideally the thicker the better so long as it flows (not straight grease). 20wt, gear oil, etc. A cheap fan isn't worth buying a jug of the stuff if you don't have any, a drop off a car dipstick (if it isn't so contaminated that it's black already) would be a good stop-gap measure if you have nothing else around that's thicker than household/3-in-1.

Beware of advice on the internet. Some mistakenly suggest really thin oil ignoring the physics involved. The original oil wasn't even that thin before the bearing had worn a bit, and then with some play in it the goal is an oil with a thicker film strength to reduce the wobble, and not run out of the bearing which it will be prone to do with the fan mounted in a horizontal orientation.

Sewing machine oil is a good first start, but it will need lubed again sooner (or replaced sooner) the thinner the oil is. The ideal oil is barely oil, just liquid enough that it doesn't blob on the side instead of staying down in the bearing and around the thrust washer. Plus, if the plug, or the washer on the blade side of the shaft doesn't seal well, thinner oil will leak out both ends faster... though it shouldn't be much of a problem if only a couple drops are used.

 

[Zepper]

Most sleeve bearings are sintered bronze type bearings where the lube is incorporated in the bearing material (often called self-lubricating). I doubt any additional lube is used. Here is a good discussion of the common types used in PC fans. http://www.nmbtc.com/pdf/forum/ball.pdf

. Single ball consists of one ball race and one, narrow sleeve bearing. There are also modified sleeve bearings used in PC fans. The original Panaflow fans have one, Sunon "Maglev" have another, and there is another called a "Rifle" bearing used in some Cooler Master fans and I've seen the word recently in connection with some other brand. Really cheap fans could have a sleeve bearing made entirely of plastic like teflon or delrin, etc.

Funny that that paper is still out there as NMB is currently the maker of the Panaflow fans whose modified sleeve bearing was specifically designed to retain the lubricant and make the longevity of the sleeve bearing similar similar to ball bearings. In any case, the positional problems of most sleeve bearings still exist. Operated vertically like most case fans they are OK but horizontally like most PSUs now, this disparity will show up.

I'd still prefer at least single ball fans for PSUs for the better axial stability and dual ball for stabiltiy plus longevity. For case fans , sleeve is the cost/performance winner and a modified sleeve can give good longevity as well.

.bh.

 

[mindless1]

There's definitely lube added later (in some fans) based on the amount of lube present besides what's inside the bearing. That could be partly why some fans seem to run longer even if they're not so great a quality either. Either way, that would still put the lube in contact with the plastic. I lube all sleeve bearing fans, it's a compulsion I suppose but it means failures are almost never seen, I've never had any problem with doing so, and some are at least 80386 era if not older though I rarely run the equipment I reused those fans in, but others over 10 years are still ok too.

I've only seen fans cheap enough to use a plastic bearing one time, for about 30 seconds (long enough to throw it away), but then I don't often take apart or research something really crude looking to know. One type that's annoying uses a bronze bearing but it's friction-fit/locking, there's no access to the shaft later to lube it (unless you drill a hole, but that leaves debris inside) and it can't reasonably be pried from the side of the hub to release it without cracking it. Some Panaflos were also made like that, but they tend to last long enough it doesn't matter.