Small DC Fan Question

I've got a small 12V DC .9 Watt 'muffin' fan (1.75"x1.75"x3/8"). It was the cooler for a video card's processor chip and was frozen up.

I put a drop of oil into its sleeve bearing and it now runs reliably - almost. It will start every time as long as it is not oriented with the open 'face' down. (The open face is the side in which you can see the bearing). If the open bearing is down, it sometimes starts and sometimes needs a slight nudge to get it going.

What's going on? How come? TIA

Reply to
Bennett Price
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Presumably because the bearings are worn out. Get another one.

Gareth.

Reply to
Gareth Magennis

The bearing may be a bit loose. I've had some success disassembling these fans, cleaning out the dried up muck, and putting on fresh oil then reassemble. It's better to replace it, but if you need to use the computer and don't have one on hand, it works in a pinch.

Reply to
James Sweet

What voltage are you applying to it?

Reply to
UCLAN

You oiled it, but you didn't get the gunk off the shaft. When the fan is oriented face down there is enough endplay in the shaft for the bit of gunk left on it to bind in the bearing. When it's face-up, that part of the shaft is likely outside of the bushing.

When doing these, I usually operate them briefly with some kind of solvent, until they run freely again. Then I flush the bearing with that solvent--blow as much of it out as possible--THEN relube with 3 in

1 type oil.

Sometimes I also pack the open space with a bit of cheap grease before resealing...figuring that if the bearing starts to get hot because of binding, some of that grease will liquefy and and replenish the bearing. I don't know if that's valid, but I usually get good life out of the refurb.

OTOH, fans are cheap and readily available...much cheaper than the stuff they protect.

jak

Reply to
jakdedert

Anywhere from 9 to 15 volts. At 9 it will run in every other position, at 15 vdc in the face down position it will still need a nudge.

UCLAN wrote:

Reply to
Bennett Price

chances are you have a pressed in race for the bearing. you maybe able to tap it in deeper if you can get to it.

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Reply to
Jamie

I've disassembled these, cleaned, and relubed with decent success.

But a new fan is not expensive.

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Reply to
Sam Goldwasser

Yes, not nearly as expensive as the possible damage caused by a stalled worn out fan that soemone tried to bodge back to working condition instead of replacing it. I'm thinking Power Amps, computer chips, or any gear that someone has paid you to fix properly.

Gareth.

Gareth.

Reply to
Gareth Magennis

Doesn't sound like anyone has paid him to fix it, the assumption is that it's his own stuff that he's fixing himself. I've been known to repair these little fans so I can keep using my PC until I can find a suitable replacement. Some graphics chipsets use oddball custom heatsink/fan assemblies that are difficult to find replacements for.

Reply to
James Sweet

Realizing that this comes under the heading of "beating a dead horse . . ."

Only one continuous long bearing supports the shaft? Some have two sleeves and you can only see one if you pull the label off - you also have to pull the shaft completely out.

I've had the same experiences with sintered bearings - the sleeve is porous and a drop of lube doesn't really do much. The thing worked for years and has a particles of grunge and a residue of dried oil filling the lubricating channels in the metal.

If the sleeves can be removed, a cleaning with an ultrasonic cleaner and some thin petroleum solvent (mindful of the hazards there) will do wonders if the surface is still round (and if you don't see scoring it probably is) - then heat the sleeve to 250 F, let it soak at that temp for an hour, and drop it into lubricating oil to cool to room temp before replacing.

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Reply to
Bennett Price

Sleeves slide around, ball bearing fans seem spring loaded, so position is less important.

greg

Reply to
GregS

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